ENGINEERING RESEARCH INSTITUTE ( i UNIVERSITY OF MICHIGAN g$/i^ ANT ARBOR,/ /.. r INTERIM REPORT NO. 3 SPECTROCEEMICAL ANALYSIS OF TITANIUM METAL AND ALLOYS By J H. E1NS Research Piysicist *, Project M973 ORDNANCE CORPS, U. S. A3MY CONTRACT NO. DA-018-ORD-11511, ORDTB 1-12045-2 August, 1953

Initial distribution has been made of this report in accordance with the distribution list contained herein. Additional distribution without recourse to the Ordnance Office may be made to United States military organizations, and to such of their contractors as they certify to be cleared to receive this report and to need it in the furtherance of a military contract.

SUMMARY SHEET I. Engineering Research Institute, University of Michigan, Ann Arbor, Michigan II. U. S. Army, Ordnance Corps, Watertown Arsenal III. O.. Project TB4-15C; RAD ORDTB 1-12045-2 IV. Report No. WAL 401/98-25 V. Priority: 1C VI. Title of Project: Evaluation of Titanium and Titanium Alloys. VII. Object: To develop a spectrochemical (porous cup) technique for the determination of Al, Mn, Cr and/or Fe in titanium-base alloys in concentrations of from 1 to 7 per cent and for the determination of these and other metals in trace concentrations. VIII. Summary: The porous-cup-solution technique described previously in the Interim Technical Report No. 2 for the analysis of Fe and Cr in titanium alloys has been extended to include Al and Mn. It is shown that all four elements may be present in concentrations up to 7 per cent each without apparent interference. The spark source parameters were changed slightly to reduce background. The method has been applied to the analysis of three specific alloys each containing two of the above elements in several per cent concentrations. Necessary corrections are worked out which take into account concentrational differences of the internal standard element, titanium. The method is also extended to include trace analysis for some metals in concentrations as low as.002 per cent. ii

DISTRIBUTION LIST Contract No. DA-20-018-ORD-1.1511 - University of Michigan Copy No. To.1 Chief of Ordnance Department of Army Washington 25, D.C. ATTN: ORDTB 2 - 3 Same - ATTN: ORDTA 4 Same - ATTN: ORDTR 5 Same - ATTN: ORDTS 6 Same - ATTN: ORDTT 7 Same - ATTN: ORDTU 8 Same - ATTN: ORDTX-AR 9 - 10 Same - ATTN: CRDIX.1 - 17 Same - ATTN: ORDGU-SE 18 - 19 Commanding General Aberdeen Proving Ground Aberdeen, Maryland ATTN: ORDBG-R. D. and E. Library 20 Commanding Officer Detroit Arsenal Center Line, Michigan 21 Commanding Officer Frankford Arsenal Bridesburg Station Philadelphia 37, Pennsylvania 22 Same - ATTN: Mr. H. Sadjian 23 Commanding Officer Picatinny Arsenal Dover, New Jersey ATTN: ORDBB-TH1, Mr. E. F. Reese 24 - 25 Commanding Officer Redstone Arsenal Huntsville, Alabama iii

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DISTRIBUTION LIST (CONT'D) Copy No. To 41 Director Naval Research Laboratory Anacostia Station Washington, D.C. ATTN: Mr. M. B. Cavanagh 42 Chief Office of Naval Research Navy Department Washington, D.C. 43 Commanding General Wright Air Development Center Wright-Patterson Air Force Base, Ohio ATTN: WCRTO 44 Same - ATTN: WCRTY - Mr. R E. Brocklehurst 45 Same - ATTN: WCRR (WCRRL) 46 Director U.S. Department of Interior Bureau of Mines Washington, D.C. 47 Chief, Bureau of Mines Eastern Research Station College Park, Maryland ATTN: M. J. Peterson 48 Chief, Bureau of Mines Boulder City Experiment Station P.O. Drawer B Boulder City, Nevada 49 National Advisory Committee for Aeronautics 1724 F Street, N.W. Washington 25, D.C. 50 Office of the Chief of Engineers Department of Army Washington 25, D.C. ATTN: Eng. Res. and Dev. Div., Military Oper. 51 Commanding Officer Technical Services Dept., ERDL Ft. Belvoir, Virginia ATTN: Allan L. Tarr v

DISTRIBUTION LIST (CONT'D) Copy No. To 52 U.S. Atomic Energy Commission Technical Information Service P.O. Box 62 Oak Ridge, Tennessee ATTN: Chief, Library Branch 53 Commander Philadelphia Naval Shipyard Industrial Test Laboratory Naval Base Philadelphia 12, Pennsylvania ATTN: Dr. Jacob Sherman 54 Laboratory Officer Navy Metals Laboratory Munhill, Pennsylvania 55 Commander Mare Island Naval Shipyard Industrial Laboratory Vallejo, California 56 District Chief Detroit Ordnance District 574 East Woodbridge Detroit 31, Michigan 57 National Bureau of Standards U.S. Department of Commerce Washington 25, D.C. ATTN: B. F. Scribner, Spectrochemistry Section 58 Sam Tour and Co., Inc. 44 Trinity Place New York 6, New York ATTN: Mr. S. Tour 59 National Research Corporation 70 Memorial Drive Cambridge 42, Mass. ATTN: Miss J. Rice 60 Armour Research Foundation Technology Center Chicago.16, Illinois ATTN: K. L. Yudowitch R. C. Carrigan 61 New Jersey Zinc Co. (of Pa.) Palmerton, Pa, ATTN: G, W. Standen Research Department vi

DISTRIBUTION LIST (CONT'D) Copy No. To 62 Rem-Cru Titanium, Inc. Midland, Pa. ATTN: W. L. Finlay and H. J. Forsythe 63 Allegheny Ludlum Steel Corp. Brackenridge, Pa. ATTN: D. P. Bartell 64 National Lead Company Titanium Division P.O. Box 58 So. Amboy, New Jersey ATTN: C. H. North 65 Kennecott Copper Corporation.120 Broadway New York, New York ATTN: Dr. H. P. Croft and P. Leichtle (Chase Plant, Waterbury) 66 P. R. Mallory and Company, Inc. Indianapolis 6, Indiana ATTN: Dr. A. R. Ferguson 67 A. 0. Smith Corporation 3537 North 27th Street Milwaukee, Wisconsin ATTN: Mr. J. J. Chyle Mr. W. J. Poehlman 68 Lucius Pitkin, Inc. 47 Fulton Street New York 38, New York ATTN: Dr. R. H. Bell 69 Brush Laboratories Company 37.14 Chester Avenue Cleveland 14, Ohio ATTN: G. F. Davies 70 E. I. duPont de Nemours and Co., Inc. Chemical Division Newport, Delaware ATTN: R. H. Fleckenstein Research Supervisor 71 Metal Hydrides, Inc. 12-24 Congress Street Beverly, Mass. ATTN: D. S. Littlehale vii

DISTRIBUTION LIST (CONT'D) Copy No. To 72 Battelle Memorial Institute 505 King Avenue Columbus 1, Ohio ATTN: W. M. Henry 73 Ledoux and Company, Inc. 359 Alfred Avenue Teaneck, New Jersey ATTN: S. Kallmann 74 Republic Steel Corporation Steel Division Canton 1, Ohio ATTN: E. 0. Waltz 75 Ford Motor Company 3000 Schaefer Road Dearborn, Michigan ATTN: R. Lesman Supervisor, Development Section Manufacturing Engineering Dept. Engine and Foundry Division 76 Titanium Metals Corp. Box 2128 Henderson, Nevada ATTN: S. A. Herres R. G. Tonkyn 77 Crane Company 4100 So. Kedzie Ave. Chicago 5, Illinois ATTN: I. J. Dzikowski 78 Monsanto Chemical Co. Central Research Dept. Dayton 7, Ohio ATTN: Dr. I. B. Johns 79 General Electric Co. Thomson Laboratory West Lynn 3, Mass. ATTN: W. H. Tobin 80 - 91 Commanding Officer Watertown Arsenal Watertown 72, Mass. ATTN: Laboratory viii

TABLE OF CONTENTS Page SUMMARY SHEET ii INTRODUCTION A. INSTRUMENTATION AND MODIFICATIONS IN PROCEDURE 2 1. Optics 2 2. Exposure 2 3. Photographic Process 2 4. Densitometer 3 5. Analytical Gap 3 6. Excitation Source Parameters 3 7. Line Pairs 6 B. SYNTHETIC STANDARD SOLUTIONS 7 1. Stock Solutions 8 2. Analytical Solutions and Curves 9 (a) Al, Mn, Cr 1-7%, Fe (0.5-3.%) 10 (b) Al, Mn, Cr, Fe, Mg, Cu, Sn (.02-0.5%) 11 (c) Mn, Mg (.002-.05%) 12 3. Solution Stability 13 C. ANALYSIS OF TI CHIP SAMPLES 14 1. Ti Base Alloys 14 2. Pure Titanium 17 REMARKS 17 APPENDIX I 19 ix

SPECTROCHEMICAL ANALYSIS OF TITANIUM METAL AND ALLOYS INTRODUCTION The contents of this report deal mainly with the porous-cupsolution technique applied to the analysis of specific samples. These are the WA samples that-were diistributed in chip form to the task force members of the Panel on Methods of Analysis (of the Metallurgical Advisory Committee on Titanium). During the course of this work, it was felt that much time might be saved if, from a single photographic exposure, the usual trace and alloying constituents could be determined. Several changes were introduced to make this possible. A rotating 3-step sector was built and installed in. front of the spectrographic entry slit. This provided photographic densities from 100, 50 or 22.2 per cent transmissions. The spark-source parameters were changed to be more arc-like. One set of five synthetic standard solutions was prepared to cover the concentration range between 1 and 7 per cent for Al, Mn, and Cr, and the concentration for Fe between 0.5 and 3.5 per cent. A second set of five analytical solutions was made up for Al, Mn, Cr, Fe, Cu, Mg, and Sn in the range.02 to 0o5 per cent. From these two sets of analytical curves, a single exposure of the unknown sample solution provided full information for the above elements. For Mn and Mg the element line-to-background ratios turned out to be sufficiently high and the concentration range was lowered with a third set of solutions from.002 to.05 per cent.' 1 -

A. INSTRUMENTATION AND MODIFICATIONS IN PROCEDURE 1. Optics A Bausch and Lomb prism spectrograph was used. The instrument is set to photograph the spectral region between 2500 and 3500 A with a 35micron slit. The source-to-slit distance is 50 cm with a 50 cm condensing lens just in front of the slit. A 50 rpm rotating step sector was built to transmit 4.5 mm line length at 100, 50 and 22.2 per cent transmissions each. 2. Exposure Unless otherwise specified below, all the analytical exposures were made at 20 seconds pre-exposure and 30 seconds exposure time. Neither the carbon cup nor the carbon counter electrode was preheated. The time-of-wait curves for Cr and Ti were direct-recorded, starting at zero time. In Figures 1 and 2 these curves are shown for two of the source parameters from Table I. Time zero begins at the right for each curve. A 20 second pre-exposure for photographic work would mean that the radiation had stabilized. With the SJIVa source in Figure 1, the exposure time was 90 seconds, while for the ST-3a source it was 30 seconds. The recorded ratios were of a line with respect to a band of radiation (2300-4000 A). The middle curve in each figure is the direct-recorded Cr line intensity. These curves show the improved stability of the ratio over the intensity. 3. Photographic Process Eastman Kodak SA No. 1 plates were used for all this work. These were developed at 68OF in D19 for 4 minutes, stopped for 10 seconds in dilute acetic acid, fixed 1-1/2 minutes, washed, and dried. Plate calibrations at 2550, 2750, and 3050A were prepared from Ti II lines in each. region. Three or four lines from a region were selected from those listed in Table I, Page 8 of Report No. 2. This provided 9 to 12 points for the H and D curve from the 3-step rotating-sector exposure. The standard 4 x 10 inch plate will hold 6 of the 3-step exposures. A calibration curve was considered reliable if a two-line ratio from the 3 steps agreed within the experimental error. __________________________________________ 2

4. Densitometer All photographic densities were read on a Leeds and Northrup microphotometer of the Vincent-Sawyer type. 5. Analytical Gap The upper electrode for much of this work has been a Type 202, United Carbon, preformal electrode, 1/4-inch diameter by 7/8-inch with a 5/32-inch-diameter cup. When a more intense type of spark excitation was desired to bring out the trace elements, the Type 203 (1/4-inch diameter by 1-1/2 inches with a 1/8-inch-diameter cup) electrode was tried and was found to cause less frequent contamination due to boiling of the solution from the top opening. Contamination was also reduced by replacing the stainless steel blocks of the analytical clamp holding the cup with carbon blocks. The appearance of solution along the elements of contact was no longer noticeable on the cup following an exposure. It is felt that the larger carbon-to-carbon surface contact prevents increasei porosity at these surfaces and what liquid does come through is absorbed by the blocks. The lower counter electrode has continued to be a 1/4-inch-diameter, grade A graphite rod. Before loading, this rod is shaped to a cone of 1300 included angle with the apex truncated to about 1/16-inch diameter. The two electrodes are placed into a loading Jig having a 4 mm spacer. Contact of the carbons with the jig are avoided by placing a small new piece of thin paper across the spacer before each loading. The carbon cup is then filled by means of an eye dropper. Care is taken to insert the eye dropper to the bottom of the cup before liquid is ejected. The solution is then forced four or five times in and out of the cup with the eye dropper still in the bottom of the cup. During the final stage enough solution is forced in to appear at the top and the eye dropper is withdrawn without further changing the volume. Flushing the cup in this manner tends to reduce the presence of air pockets that might cause the liquid to be blown from the cup during sparking. From the loading jig, the electrodes are transferred directly to the analytical gap, as is common practice with metal pin samples. 6. Excitation Source Parameters In Table I are listed several source parameters that were tried during the course of this work. The discharge circuit parameters in each column are sparks per half cycle with the air-interrupter-type source, ~ _____________________________________

TABLE I EXCITATION SOURCE PARAMETERS Source Sparks C R L I KV W per,h c. S-IV 4.002 2.1 15 5 15.5 31 S-IVa 4.002 1.1 45 5.5 15.5 41 ST-2 2.006 1.1 90 5 14 57 ST-3 3.006 1.1 10 10 14 51 ST-3a 3.006 1.1 90 7 14 79 C in microfarads, R in ohms, L in microhenries, I the r. f. amperes, KV the kilovolts and W the computed analytical gap energy in watts.* The energy W is difficult to'compute and the values given are only approximate. It is significant, as will be shown below, that there is a general increase in W for the sources as they are listed. The approximate twoto-one ratio in W for the ST-3a and the S-IVa source is also obtained for the radiation intensity from these two sources. The ST-3 source was originally chosen (page 2, Report No. 1) as being well suited for either the porous-cup technique or direct metal excitation. A metal surface sparked by this source appeared uniformly sampled. When it became of interest to determine the trace elements, the inductance was increased to 90 microhenries. This is a more arc-like discharge. The result is an improved line-to-background ratio which was most noticeable for the 3092 Al line. The ST-3a source was used for most of the analytical work reported below. An important observation at this point was that going from ST-3 to ST-3a caused no noticeable change in the ratios of the element lines to the See Enns, J. H. and Wolfe, R. A., J. Opt. Soc. Am., 39, 298(1949) ~ k ~^~~~~~~~~

internal standard line. It had been established earlier (page 9, Report No. 2) that the closey matched- excitation energies for the two line ratios Fe 2755 and Cr 2762 were not affected by thermal changes in the discharge. Ti 2761 Ti 2764 At this point there were no indications of differential evaporation with the porous-cup technique. Evidently all elements entered the discharge in a constant ratio, regardless of the type of discharge. This led to a test by -;. which it was felt that the optimum excitation parameters for direct metal sparking could be determined. In direct metal sparking, differential evaporation is known to exist. For this test, chips were cut from one end of a 1/4-inch-diameter pin of titanium alloy 150A. This alloy has the nominal concentrations of 1.3% Fe and 2.7% Cr. From these chips, a solution of standard concentration (20 mg per ml) was prepared. The logarithmic intensity ratios for the line pairs of the preceding paragraph were then determined. For both Fe and Cr these ratios remained unchanged as the source parameters were changed according to Table I. The identical procedure was then followed to determine the logarithmic' intensity ratios for-the metal pin froi-wihich the chips had been cut. The flat-ended metal pin replaced the porous cup as the upper electrode. The results are tabulated in Table II. In the first row, the log I and intensity (I) ratios are listed for any one of the sources from the porous cup, and below these are listed the ratios from direct sparking of the metal pin by the different sources. The logarithmis are to the base 1.5. TABLE II EXCITATION SOURCES VS LINE RATIOS Fe 2755 Cr 2762 Ti 2761 Ti 2764 Source Sample Log I I Log I I........_. Any one 150A-Sol. -.20 0.92 -.63 0.77 S-IV 150A-Met. -.26 0.90 -.72 0.75 ST-3 150A-Met. -.58 0.79 -.84 0.71 ST-2 150A-Met. -1.38 0.57 -1.19 0.62 ST-3a 150A-Met. -2.20 0.41 -1.44 o.56 ~- -^ ~- -- - ---

According to the above data, relative element vaporization from the metal directly approaches that from the solution for the least intense source, S-IV. This behavior in differential evaporation is thought to be due to the great differences in thermal properties of these elements. For example, the boiling temperature for Ti is given as 5100~C as compared to 3000"C for Fe and 2482~C for Cr. Similar results have recently been obtained for Mn in a Ti base alloy containing 7% Mn. The boiling temperature of Mn is 2150~C. Thermal conductivity of the metal sample and the clamp are also known to be of importance. If it is assumed that the relative vaporization of the elements from the porous cup or any solution technique is in a constant ratio, and if it can be shown that this ratio is the most stable ratio for direct metal excitation, then it seems logical that the above procedure should be followed for the determination of optimnum excitation parameters for all direct metal analysis. The above data shows that there is no advantage in sensitivity by going to more intense excitation, The ratio of the element line to the internal standard line increases with decreasing source intensity. Until now, the above test has not been applied to trace concentrations. In the near future this laboratory will continue the investigation of excitation parameters for direct metal analysis. 7. Line Pairs (Conc. Index) a. Major Constituents Mn II 25588.59 ) MnII 2993 (3.) Ti II 2581.72 3 Ti II 2890'61 *.l Al I 2575.10 Al I 3092.71 Ti I 2619.94 Ti I 29 6.79 * Fe II 2755.74 Cr II 2762.59 Ti II 27129 (1 ) Ti II 2764.82 (%) Al I 3961.52 Ti I 396 5434 6 _

b. Trace Elements Mn II 2576.1 0 Mn II 2605.68 ) Ti II 2'581..72 -(~' Ti II 2519.81 Mg I 2852.13 Mg I 2852.13 Ti II 28393 ( ) Ti II 2880.29 (' Cr II 2835.63 Fe II 2599. 14 (0.14%) (0o13%) Ti II 2815.55 Ti II 2568.9 Al I 3092.71 u I 273.96 Ti I 3114.09 (.08%) Ti I 3299.41 (01%) The Mn 2558 line is preferred over the Mn 2993 line because of its lower intensity. With either the ST-3 or ST-3a source parameters, a 30second exposure time results in useful photographic densities for Mn ^558, whereas the Mn 2933 is too intense even from the 22.2% transmission step. The Mn 2933 line has the desired intensity with the weaker parameters of S-IV or S-IVa. The Al 2575 line is interfered with by Mn and for that reason the Al 3092 or Al 3961 line is preferred. With the prism instrument of this laboratory set to record below 3300A, the Al 3092 line was decided upon. The Al 3961 line is being used at the Battelle Memorial Institute with a grating spectrograph set for the second order. Through the courtesy of Mr. W. M. Henry, their data is presented here. The analytical solutions used were from the University of Michigan, and the data were taken with the lucite cup arrangement discussed in section B-2a and Appendix I. Curves for Mn, Cr, and Fe from the Battelle data have essentially the same slope as shown in Figure 3. B. SYNTHETIC STANDARD SOLUTIONS There have been few changes in the technique of preparing standard solutions as described in ReportNo. 2. Errors in weights and volumes are minimized by measuring at least 1 gm and 1 ml quantities. All synthetic solutions were prepared from Ti metal stock solutions instead of TiO2. This eleminates the presence of excess concentrations of low excitation energy elements like K or Na. 7

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN 1. Stock Solutions Ti. The Ti stock solution was made up to a concentration of 20 mg per ml from either WA-13 (high purity iodide titanium) or Du Pont No. 4 titanium sponge (Table V). A standard procedure was to add 30 ml of concentrated H2S04 and 10 ml conc. HC1 to 100 ml of H20 in a 250 ml Erlemyer flask. To this solution, when thoroughly mixed and not too hot, 4 gm of Ti metal chips were added. The mixture was kept at a low heat (without boiling) on a hot plate until all chips have been dissolved. More rapid heating with some decrease in dissolving time was also tried in connection with a watercooled reflux condenser. In either case, the addition of HC1 was considered important in that this avoided a whitish deposit on the container walls above the solution level. From its appearance, the deposit was surmised to be a titanium-sulphur compound.. About 2 ml of conc. RNO was slowly added to the solution when it was certain that all chips had been dissolved. This oxidized the Ti +++ to Ti ++++, causing the original dark-purple solution to become perfectly clear and colorless. Excess oxides of nitrogen are expelled by continuing the heating on the hot plate for about 10 minutes. Two gm of tartaric acid were then added to complex the titanium. The solution was transferred to a 200-ml, volumetric flask and made up to volume with H20. The same procedure was followed when dissolving unknown Ti samples. Sample weights of 1 gm each were dissolved and made up to a volume of 50 ml. All the other quantities were measured proportionately. Al. This stock solution has caused some difficulties, since it tends to be unstable unless of proper acidity. The most recent and apparently perfectly stable solution was prepared by dissolving a 2-gm piece of high purity (ALCOA-R519-99.99%) aluminum in 60 ml of HC1 at low heat on a hot plate. The solution was made up to 100 ml with H20 so that its concentration was also 20 mg per ml. When the same procedure was tried with standard purity granular Al metal, the solution again was slightly yellow and turbid inducting iron as an impurity. Mn. A 20-mg-per-ml stock solution was prepared by dissolving 6.16 gm of MnS0O4H20 (Mn = 2 gm) in 120 to a total volume of 100 ml. Cr. A stock solution containing 20 mg per ml was prepared by dissolving 5.657 gm of K2Cr207 (Cr = 2 gm) in 25% cone. H2S04 made up to a total volume of 100 ml. 8

Fe. This stock solution was prepared by dissolving 7.022 mg of FeS04 (NH4) S0o46 H20 (Fe = 1 gm) in 25% conc. H2S04 to a total volume of 100 ml. The resulting concentration was then 10 mg. of Fe per ml. Cu. A 20-mg-per-ml Cu solution was prepared by dissolving 2.5046 gM of CuO (Cu = 2 gm) in 25% conc. H2S04 made up to a total Volume of 100 ml. Sn. Two grams of pure Sn metal were dissolved in 60 ml cone, HC1 and made up to 100 ml with H20. Mg. Two grams of pure Mg metal chips were dissolved in a 25% conch HC1 solution made up to a total volume of 100 ml. 2. Analytical Solutions and Curves Three sets of standard solutions for the analysis of the WA samples have been prepared. Five solutions in each set cover the concentration ranges of (a) 1-7%, (b).02-0.5 and (c).002-.05%. The above figures are to be considered either with respect to 100% Ti (the internal standard element) or, as their actual use below will indicate, as the percentage ratio of an element to Ti multiplied by 100. The concentration of the internal standard element Ti may not be known in high-alloy materials; it may differ appreciably from the standards. If instead of percent element concentration, the percentage ratio of element to internal standard (xlOO) is plotted, both difficulties are overcome. If it is assumed that the total element plus Ti content is 100% in an unknown sample, then it can be shown that the percent titanium is Ti = _100 1 +Er". where the" is taken over all the percentage ratios of the n elements to where the~ is taken over all the percentage ratios of the n elements to Ti. As a rule, the summation needs to include only the alloying elements to account for 98 to 99% of the total. According to the above expression it is convenient to plot the WAnalytical curves as Er/Ti against the respective two-line intensity ratios. Since, by the internal standard method, En/Ti is readily determined for any unknown sample, Ti itself is also obtained from the above equation. The final step is to multiply each of the En/Ti values for the sample as obtained from the curves, by Ti. The result is En, the percent element concentration. 9 i

The one limitation to this method is that self-reversing lines, causing appreciable nonlinearity in the analytical curves, should not be used. a. Al, Mn, Cr 1-71, Fe 0.5-3 5. This set of standards was made up to analyse for three of the alloying elements with nominal concentrations up to 5 percent and for Fe up to-1.3%. Each alloy was known to contain only two of the four elements as major components. Before mixing one set of solutions containing all four elements and Ti, two-element solutions were made up to match the particular alloys. A comparison of results showed that element interference was not serious and could be avoided. The A1-2575 line was replaced by Al-3092 because of Mn interference. The amount of labor required for setting up analytical curves is appreciably reduced by using the four element solutions. The highest concentration solution (7% Al, Mn, Cr, and 3.5% Fe) was made up by mixing 50 ml of Ti stock solution (Du P No. 4) with 3.5 ml from each of the four element stock solutions. Since the concentration of each stock solution is 20 mg per ml (except Fe being 10 mg per ml), the total volume m (64 ml) contains 1000 mg Ti, 70 mg of Al, Mn, and Cr each, and 35 mg of Fe. The percentage ratio of element to Ti is obtained directly from the ratio of their weights above. Lower concentration ratio solutions were prepared by diluting portions from the (73*.5) solution with appropriate volumes of Ti (Du P No. 4) stock solution. The x ml of Ti solution that must be added to n ml of the (7,3.5) solution to obtain lower concentration ratios, can be computed directly from n [ l00q where k is the Ti stock-solution concentration (20 mg per ml), m is the total volume of the (7,35) Bsolution, q is the mg weight of the s-percentageratio element in the original m volume, and p is the mg weight (1000 mg) of Ti in the m volume. Accordingly, the five solutions were mixtures of: 7% Al, Mn, Cr-3.5% Fe: 3.5 ml of Al, Mn, Cr, Fe stock solution + 50 ml Ti stock solution 4.5% Al, Mn, Cr-2.254 Fe: 16 ml of (7,3-5) solution + 6.94 ml of Ti solution 3A Al, Mn, Cr-l. Fe: 8 ml of (7,3.5) solution + 8.33 ml Ti solution 10

2 Al, Mn, Cr-lI Fe: 8 ml of (7,3.5) solution + 15.63 ml Ti solution 1% Al, Mn, Cr-0. Fe: 4 ml of (7,3.5) solution + 18.75 ml of Ti solution The analytical curves from these solutions are shown in Figure 3. Each point is the average from three exposures with the ST-3a source. The known residual concentrations of.014% Fe and.015 Mn in Ti (Du P No. 4) are corrected for by adding these values before plotting. At high percentages and with the logarithmic scale, the residual effect is noticeable only for one or two of the lower points on the graph, In Figure 4, three Al curves from the same University of Michigan standard solutions show the improved slope of the Battelle data (curve 3). Curve 1 represents University of Michigan data with the ST-3a source but with the full available inductance of 310 microhenries. Curve 2 was taken with the regular ST-3a source. Since curves 1 and 2 are almost parallel, the small slope of the Battelle data is not explained by the use of a more arc-like discharge. The slope of the Mn, Cr, and Fe curves from the Battelle data are essentially the same as those shown in Figure 3. b.Al, Mn, Cr, Fe, Mg, Cu, Sn (.02 - 0.5 ). A mixed stock solution was made up to a concentration of 1 mg per ml of each of the seven elements. This was done by measuring out 5 ml from each of the 20-mg-per-nml stock solutions (except 10 ml from the Fe stock solution whose concentration was 10 mg per ml) and adding 25% concH2S04 to a total volume of 100 ml. The five standard solutions were then prepared from this seven element stock solution and the Ti (Du P No. 4) stock solution. The procedure was the same as outlined above for the high percentage mixtures; that is: 0.5% Solution (m = 55 ml, k = 20 mg per ml, q = 5 mg, p = 1000 mg) 5 ml of 7 element solution + 50 ml of Ti 0.2 Solution (n: = 8 ml, s = 0.2): 8 ml of 0.5% solution + 10.9 ml of Ti 0.1% Solution (n = 5 ml, s = 0.1): 5 ml of 0.5 solution + 18.15 ml of Ti.05 Solution (n = 3 ml, s =.05): 3 ml of 0.5% solution + 24.55 ml of Ti.02% Solution (n = 1 ml, s =.02) 1 ml of 0.5% solution + 21.8 ml of Ti 11 _____________________________________

The Du P No. 4 Ti solution has residuals of.014% Fe,.015% Mn and.06% Mg. These values were added to the percent ratios for the plotting of the analytical curves. Direct addition is permissable because the residuals are essentially with respect to 100% Ti, and this as was shown above, is equivalent to percentage ratios. The analytical curves from the above solutions are plotted in Figures 5, 6, 7, 8 and 9. The spectrochemical values of the four Du Pont samples have been superimposed on the basis of their chemical values for Fe, Mn and Mg. From the good agreement between the two it must be concluded that the analytical solutions are essentially correct. The 3034.12 SnI line was chosen as the most suitable line on the basis of intensity and freedom from interference. However, the 0.2% solution was the minimum concentration at which the line could be read. Sn was not detected in any of the WA nor the Du Pont samples. Because of insufficient intensity, the Sn curve has been omitted from this report. c.Mn, Mg (002-.0).t The straightness of the Mn and Mg curves for the.02 - 0.5% solutions (Figures 7 and 8) indicates that for these two elements the concentration range can be lowered without the curves becoming too steep. Solutions were prepared with all the seven elements present simply because of the available stock solution. A more dilute 7-element stock solution was prepared by diluting 5 ml from the l-mg-per-ml stock solution with 95 ml of 25% concH2S04. The concentration of each element was then.05 mg per ml. The Ti stock solution in this case was from WA-13 chips because of the lower Mn and Mg content as compared with Du Pont No. 4. The residauais (Mn =.003%, Mg =.0006%) are the spectro-chemical values from the Batbelle Memorial Institute. The method of mixing, outlined in paragraphs a and b above, was repeated as follows:.05 (m = 36 ml, k = 20 mg per ml, q = 0.3 mg, p = 600 mg) 6 ml of 7 element solution + 30 ml of Ti.02% (n = 8 ml, s =.02) 8 ml of.05% solution + 10 ml of Ti.01j (n = 6 ml, s =.01): 6 ml of.05% solution + 20 ml of Ti 12

.005% (n = 3 ml, s =.005) 3 ml of.05% solution + 22.5 ml of Ti.002% (n = 1.2 ml, s =.002): 1.2 ml of.05% solution + 24 ml of Ti The Mn and Mg curves for these solutions are shown in Figures 10 and 11 respectively. Each point is the average value from two exposures with the S-IVa source parameters. The pre-exposure time was 20 seconds and the exposure time was 90 seconds. No appreciable shift was observed when these solutions were run with the ST-3a source. The superimposed chemical or spectrochemical values from other determinations are mostly in good agreement. For example, the chemical Mn values for Du P No. 1 and No. 3 (.*003), the Mn spectrochemical value by Battelle for WA-13 (o003%), and our spectrochemical analysis of all three samples check. QOir Mn concentrations shown as x in Figure 10 are determinations from the curve of Figure 7- Samples WA-O1 and WA,-12 were single exposure data, which might explain the somewhat larger deviation for WA-10. From the relative location of the Du Pont samples 1, 3 and 4 for Mg in Figures 8 and 11, it appears that.06% for No. 4 is high and should be.05 to.052. This would mean that the residual addition of.06% in Figure 8 is too high. If in Figure 8 the residual addition is reduced to.05% the separation between the Du Pont curve (points 1, 2 and 3) and our analytical curve becomes even greater. 3. Solution Stability The procedure of preparing synthetic standards as outlined above has been found to be reproducible to within the usual spectro-chemical error of + 2 percent. The 1-7 per cent solutions werel prepared.'independently on three occasions. Only the Al curve showed a shift, and this was attributed to unstable Al stock solutions. Since our final Al results for unknown samples check with those from another laboratory, it is felt that the Al stock solution prepared as outlined in section B-l is now equally reliable. In table III the logarithmic intensity ratios are tabulated for the.02-0.5 per cent solutions as determinedi by'two different operators from the same set of solutions. The time interval between the two data taken was two months as shown by the dates in the second column. The data taken on 5-7-53 is the average of three exposures, except Cu which was a single exposurewith'the 7/8-inch-long cups held by an all-metal clamp. The data 13

taken two months later is from single exposures with 1-1/2-inch-long cups held by the carbon block clamp. With few exceptions the two data are in good agreement. TABLE III TWO-MONTH STABILITY TEST OF ANALYTICAL SOLUTIONS Solution Element Date.02%.0 0.1% 0.2%!0. 5 Mn 5-7-53 _.95 +. 35 +1.5 +2.7 +4.45 Mn 7-6-53 -.87 +.31 +1.46 +2.88 +4.33 Mg 5-7-53 -.45 -.20 +.69 1.6 Mg 7-6-53 -.49 -.13 +.21 +0.82 + 1.47 Fe 5-7-53 -2.03 -1.20 -.20 +1.0 +2.85 Fe 7-6-53 -1393 -1.23 -.26 +.97 42.78 Ai 5-7-53 -.96 -.36 +.18 +1.12 +2.57 Al 7-6-53 -.71 -.22 +.39 +1.13 +2.55 Cr 5-7-53 -1.92 -1.29 -.50 +.47 2.16 Cr 7-6-53 -i.93 -1.32 -.57 +.48 +2.02 Cu 5-7-53 -1.60 -.87 +.13 +1.03 +2.90 Cu 7-6-53 -1.46 -.74 -.02 +1.00 -2.37 C. ANALYSIS OF TI CHIP SAMPLES 1) Ti Base Alloys Three alloys of nominal concentrations 5 Cu - 3 Al- 92 Ti (WA-2), 4 Mn - 4 Al - 92 Ti (WA-9), and 1.3 Fe - 2.7 Cr - 96 Ti (WA-12) have been analyzed for both the alloying and trace- elements as tabulated in Table IV. 14

Each sample was run twice on one plate, and five plates were taken. On plate I, every exposure was with a freshly loaded cup. On the last four plates, the two exposures of each sample were from the same cup without reloading, Otherwise all exposures were taken in the same manner with the ST-3a source. The per cent concentrations were determined from the curves according to the procedure described above. That is, for each alloy the Ti concentratian was first determined, and then all element-to-Ti ratios taken from the curves were multiplied by the percent Ti to obtain the per cent element present. According to the data of Table IV, at high concentrations individual determinations repeat to within +-3 of the amount present for Fe, Cr, and Mn and to within *7% for Al. One reason for the large Al error is the steepness of the Al curves The maximum deviation in the log I ratio for Al was +0.11 compared to ~.06 for the other three elements. The Al-ratio error corresponde to only i5% of the amount present if read from a curve with a slope equal to that of the other three elements. There is, of course, a definitely larger variation in the log I ratio for Al and this must originate in technique previous to the recording. 15

TABLE IV PERCENT CONCENTRATIONS FOR 10 REPEAT EXPOSURES Sample Plate Fe Cr Mn Al Mg Cu Ti WA2 86 0.130 5.12.040 3.41.0075.01 91.5 86 0.134 5.02.041 3.34.0073 87 0.135 4.96.040 3.29.0073 87 0.129 5.08.041 3.38.0075 88 0.129 4.93.041 3.37.0071 88 0.131 4.94.041 3.34.0090 89 0.129 5.03.042 3.48.0078 89 0.131 4.95.041 3.68.0082 90 0.133 5.14.042 3.56.0077 90 0.135 5.02.041 3.53.0081 Average 0.132 5.02.041 3.44.0076 Max. Dev. +.003 -0.12.001 ~0.24.0014 WA9 86 0.233 <.01 3.46 3.4o.0018.032 93.2 86 0.231 3. 52 3.36.0019.032 87 0.226 3.37 3.41.032 87 0.224 3.45 3.37.0019.037 88 0.224 3.37 3.35.038 88 0.235 3.37 3.38.0022.041 89 0.219 3.43 3.57.0021.041 89 0.221 3.43 3.59.0022.042 90 0.233 3.54 3.63.0019.035 90 0.224 3.50 3.66.0020.037 Average 0.227 3.44 3.4.0020.037 Max. Dev. +.008 +0.10 +0.19 +.0002 +.005 WA12 86 1.47 2.69 o094 0.166 00o41 oo096 96.0 86 1.46 2.73.093 0.165 87 1.46 2.69.093 0.163.0041 87 1.46 2.69.089 0.158.0041.01 88 1.47 2.67.091 0.180,0042.012 88 1.46 2.73.092 0.190.0034.011 89 1.47 2.67.092 o.160.0045.016 89 1.47 2.69.091 0.161.0041.014 90 1.44 2.68.090 0.154.0042.011 90 1.44 2.66.090 0.157.0044.012 Average 1.4 2 —9.092 0.165.0041.0112 Max. Dev. ~.02 +.04 -.003. 025.0007 -.oo48 16

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN The average Cr values for WA-2 and WA-12 are again below the chemical values reported at the New York meeting in April, 1953 (5.13 and 2.75 respectively). The Al results for WA-2 and WA-9 are now in good agreement with the spectrochemical values from the Bureau of Mines as reported at the New York Meeting. The other values are, as a rule, in good agreement with those reported earlier. 2. Pure Titanium The trace concentrations in iodide titanium (WA-13) and titanium sponge were determined by the same procedure as in the alloys. In these, the Ti concentration is nearly 100%. The analytical curves may then be considered as direct per cent concentrations. The averaged results are tabulated in Table V. Except for the additional low Mn and Mg determinations, the percentages of this table were included in the report distributed at the 2nd meeting of the Panel on Methods of Analysis, New York City, April 23-24, 1953. REMARKS It may be concluded from the data of this report that for the porous-cup technique, the source parameters are not as critical as for solid-sample analysis. Also it seems quite certain that a less intense source with a longer exposure time will yield equal or better results than a more intense spark. We intend to reproduce the data of Table IV with the S-IVa parameters. A similar or even feebler spark is expected to give the best results for direct Ti metal analysis. Occasionally, sample solutions were made up to 10 mg per ml instead of the standard 20-mg concentration. There were no observed changes in the log I ratios. Future plans are to complete the comparison of the porous cup, lucite cup, and the rotating disco Ti chip samples with V as the alloying element are to be analyzed by the porous-cup technique as here described. Direct Ti metal analysis is to be resumed with samples recently supplied by Watertown Arsenalo 17

TABLE V TRACE ELEMENTS IN IODIDE AND SPONGE TI Sample Fe Cr Mn Al Mg Cu WA-10.23.01 0o56 <.01.0041 <.01 WA-13.054 <.01.003 <.01.005 <.01 DuP-1.051 <.005.0028 (.01.044 (.01 DuP-2 0.31 <.005 0.104 <. O 0.10 <.01 (WA-16) DuP-3.089. 005.0032 <.01.075 < 01 (WA-17) DuP-4.016 <.01.015 <.01.056 <.01 (Du Pont Chemical Values) DuP-1.06.003.04 DuP-2 0.30.082 0.10 DuP-3 0.10.003.07 DuP-4.014.015.06.... 18 -—.-8

APPENDIX I 19

SOLUTION ANALYSIS BY THE LUCITE CUP The lucite-cup technique has been tried with cups obtained directly from the Battelle Memorial Institute. The analytical curves in Figure 12 were taken by this method, with otherwise the same parameters and solutions as used for the curves of Figure 3. The photographic densities were lower, corresponding roughly to half the radiation intensity. A more important effect is the improved slope of the Al curve. The line-to-background ratio is noticeably higher than with the porous cup. The reason for this is not clear, except that in our arrangement with the lucite cup the carbon counter electrode had to be slightly out of the optical system. Additional tests with the lucite cup as well as the rotating-disc arrangements are now in progress. 20

6 XRatio Cr 2762 2300-4'00A Intensity Cr 2762 O jec Ratio Ti 2764 2300-4000A Figure I Direct-Recorded Time-of-Wait Curves for Porous-CupSolution Technique with S-IVa Source. Full scale Reading is 100.

|| 1 I!'! IL I Rat tio Cr 2762 2300-4000A Ratio i 27614 Rato 2300-4000A FIGURE II Time-of-Wait Curves for Porous-Cup-Solution Technique with ST-3a Source. (About 2 times the Radiation Intensity of the S a Source).276,,. 4 30 Scl. - ~ ~ i I I I I I I I I 1 a Ratio 2300-4oooA FIGURE II Time-of-Wait Curves for Porous-Cup-Solution TechRadiation Intensity of the S IVa Source).

10.0 9.0 A Mn 8.o 7.0 6.o1 50- Eleme Element T' i Ti 295 1,0 / /~ ~~.~ Mn 2558 _ 0.9 ~ ~~~~Ti 258-1 0.9 0.8 ~.. Cr 2762 -,/~~~. ~Ti 276g 0.7 Fe 2755 O. 6 ~. Ti 2761 - 0.5'~' 0.4 0.3 ~~ 0.2 -3 "2 -1 0 1 2 3 r'= log I Ratio Figure 3. (1 - 7)

8.o.. I 2 - 7.0 6.o 50 2.0 ~x 100o/ 2.0.... Al 3092 i 2 95 of Mo 10 ph 2 A 2956 U. of M. 90 ph 1.0 Al 3961 0.9 ~ ~~ 8 Ti j95 Battelle 410 lh0.8 0.7 0.5 0. 6~4_ 0.3.~~~ 0.2 0 -3 2 = 0 21 Figu re (1 - 7 Figure 4. (1-7%)

0.4 0.5 Cr 2855 ____ Al 3092 0.2 Ti 2815 I Ti 311, Element | i et x 100 / / 0.1 0.09 ~~~......~~ 0.07 l/ ~ 7...~ 0.0..o6 0.05 i.. -0.04 /~~ / o log I Rt io F 5 0.01 ~ I1~~ -3 -2 1 0 12 3 r = log I Ratio Figure 5. (0.02 0.5*)

* Standard Solutions from No. 4 0; 5 o DuP Solutions Nos. 1, 2, 3, 4 o. o8 0.4. 0,3 05 0.1 ~. 32 -1 0 1 2 35 0.09 5 ) 0.08 0.07.... o.06...., 0.05 ~~~ 0.03 ~ -~~ 0.02' 0.01 ~~___ ~3 "2 -1 0 1 2 3 r Figure 6. (0o02 - Oon)

o.6 0.5..... ~0.4 ____ * Standard Solutions from Noo 4 0 DuP Solutions Nos. 2 and 4 Mn 2576 0.3 Ti 2581 Mn 0.2 X ~Ti 0 10 - 0.09.. 0.08 ~ o2 - 0.07.~....~..~ 0.06 o. o6 0.05 0.03 0.02 k4 0.01 ~ —2 -1 0 1 2 3 4 r Figure 7. (0.02 - 0.5)

01.0' 0.9 0.8 0.7, o.6 0.5 Mg 2852 Ti 2853 0. 4.../~... 0.3 0.2 0.1. 2. 0.08 0.07 3 0.02________________/ ~Standard Solutions from DP No. 4 - 0.09 O. 08 0.07... 0.0 -2 -1 0 1 2 r Figure 8. (0.02 - 0.5)

O.e 0.4I l l l l/ Il 0.3 %.bCu C u 3273 0.2 x 100 T 52l 9 0.1... 0.09 ~~~~ 0.08 0.07 o. o6 0.06 ~......~ 0.04 0.02 0.03 30.02 1 2 3 4 r Figure 9. (0.02 -0.~)

0.1 WA 0.09 0.08 ~~/ 0.07 0oo6. WAo-1 Mn 2605 0.04 - 0. 05 t Ti 2519-| WA2 2 0. o~ 0.03 Mn 100 u x ioo I 0.02 * Standard Solution from WA~13 )O No. 1, No. 3, No. 4 DuPont Chemical )/ WA-2, WA-10, WA-12, WA-13 Battelle Spectrochemical 0.01 0.o 009~ / X WA-2, WA-10, WA-12 University 0.~~~/ ~ _____of Michigan Spectrochemical 0.007 o. oo67 0.005 o. oo4 0.003 WA1ll 0.002' ~' r Figure lOo (0.002 0.05%)

o, o8 0.07 3 0.06 4~ ____ __~~ 0.02 0.101 -%Mg _ ~~~~ Mg 2852 0.009 -Ti 10 TI 2880 0.008 0.007 0.005 o. 004 Figure 11. (0.002 - 0.05%) 0.003 Standard Solutions from WA-13 0.002_ 0 / |. o DuPont Chemical Values 0.002 ~ -/ ~~ x Battelle Spectrochemical 0.001 / o. aoo9 / 0.0009 o.ooo8 o~o 0.0007 o.ooo6 ~ WA-1 ~ 0.0005 0 o. o004 0.0003 0.0002 0. 0001 ~ 3 2 1 0r 1 2 5

10.0 Cr 8.o 7-.o 6.-o 4.0. Element x 100 2.0 __________:1.0 C______________II 0.9. o ~8 _~~~Al 3092 Ti 2956 0.7 ~~~__~~ __ 0.6 Mn 2558 Ti 251 0.95.. Cr 2762 Ti 2764 0.8 Fe 2755 Ti 2761 0.3.2-4 -3 -2 1 0 1 2 3 Figure 12. (1-7,~ Lucite Cups)