Work Description

Read-Me file dataset of “Topological transitions of spiral eutectics”
Saman Moniri and Ashwin J. Shahani
Contact: moniri@umich.edu

Research Overview:
Recent reports have offered the synthesis physics of two-phase spiral eutectics in the Zn-Mg alloy system. The hierarchical nature of these spiral composites necessitated multiple experimental probes to unearth the origin of spiral growth. Collectively, the results demonstrated that the spiral formation follows a two‐step process, wherein the first step is mediated by the low solid–liquid interfacial energy of a precursor phase, and the second step by crystallographic defects on the precursor. The present study reports the behavior of these spiral composites under both short- and long-term isothermal annealing. The in situ annealing experiment was performed at the Full Field X-ray Imaging (FXI) beamline of the National Synchrotron Light Source II (NSLS-II) in Brookhaven National Laboratory; it is important to note that the in situ capability of performing these experiments at temperature is a very recent addition to the beamline (fall 2019) and provides an unprecedented opportunity to probe dynamical events at high spatial and temporal resolutions.
The results are further corroborated with ex situ characterization studies, including compositional and crystallographic analyses. Collectively, the results identify the dynamics of annealing-mediated structural transitions in spiral Zn-MgZn2 eutectics by illustrating (i) the occurrence of a solid-state transformation (precipitation) from the metastable Zn-MgZn2 to the stable Zn-Mg2Zn11 eutectic at short timescales (up to 10 minutes), and (ii) the non-self-similar evolution of the structure at prolonged timescales (10 hours).

Methods:
The data file contains X-ray projection images collected at the National Synchrotron Light Source II in Brookhaven National Laboratory (Upton, NY). Pre-processing of data involved extraction and reconstruction of projection images from the .hdf raw data file using TomoPy toolbox in Python. Then, computer vision algorithms were developed in MATLAB to process (segment) the images followed by 3D visualization and quantitative analysis.

File Inventory:
The data is comprised of 20 .hdf files of the X-ray projections recorded during isothermal annealing of Zn-Mg samples, at discrete time-steps shown below for files names ending in ‘...30141’ to ‘…30161’:

30141: prior to annealing; 30142: 1 min annealing; 30143: 3 min; 30144: 5 min; 30145: 7 min; 30146: 10 min; 30147: 15 min; 30148: 20 min; 30150: 31 min; 30151: 1 hr; 30152: 2 hr; 30153: 3 hr; 30154: 4 hr; 30155: 5 hr; 30156: 6 hr; 30157:7 hr; 30158: 8 hr; 30159:9 hr; 30160: 9 hr, 10 min; 30161: 10 hr

The raw data file is in .hdf format and can be reconstructed into .tiff, e.g., by using the TomoPy toolbox in Python.

Funding Information:
• AFOSR program under award number FA9550‐18‐1‐0044
• Brookhaven National Laboratory. DoE Grant Number: DE-SC0012704

Use and Access:
This data set is made available under a Creative Commons Attribution license (CCBY). Restrictions apply for publishing with the data presented here. Please contact author Saman Moniri (moniri@umich.edu) for further information and permission.

Suggested Citation to the Data:
Saman Moniri and Ashwin J. Shahani, “Topological transitions of spiral eutectics” [Data set]. University of Michigan. https://doi.org/10.7302/v73g-tn9