A computational framework for modeling irradiation creep and swelling in single crystal nickel

Abstract

A computational framework for modeling irradiation creep and swelling is developed to estimate creep strains, swelling strains and the dose dependent evolution of microstructural characteristics such as dislocation density, void number density and void size in pure, single crystal metals. This work represents an attempt to construct a comprehensive and self-consistent description of the physical processes that occur during the application of temperature, stress, and irradiation, in that cross-talk between individual microstructural models is allowed during their mutual evolution in time. The coupling of microstructural evolution to the strain generating models is responsible for the following results: the variation of the steady state creep rate with dose in the early part of the irradiation history; the observation that irradiation creep displays a maximum in temperature and falls off at high temperature, similar to swelling; the linear dependence of steady state creep on stress with a discontinuity at a = 0 resulting from the influence of stress on the void number density. The major violation of self-consistency is the isolation of void nucleation from the microstructural evolution. The magnitudes of creep strains computed with the model compare favorably with measured values for nickel.