Phase Field Study of Voids Evolution and Migration of Fe-Cr Alloy upon Temperature Gradient
The austenite Fe-Cr steels,the critical in-pile components,has been in service for a long time under high temperature and irradiation;the irradiated vacancies aggregate into voids leading to irradiation swelling and hardening.In this paper,the phase field method coupled the central temperature field and one-dimensional temperature field was used to study the vacancy clustering and voids'evolution behavior of Fe-Cr alloy.The calculation results show that in the central temperature field,the temperature gradient promotes the migration of vacancy to the region with high central temperature,leading to high vacancy concentration in the central high temperature region,giving priority to void nucleation and large void size;while is leads to low vacancy concentration and small void size in the low temperature region.In one-dimensional temperature field,under the control of bulk diffusion mechanism,the migration velocity of the void is positively correlated with the temperature gradient,but not with the initial radius of void.Under the control of the surface diffusion mechanism,the migration velocity of the void is positively correlated with the temperature gradient but negatively correlated with the initial radius of void.The results of this study provide insights into the prediction of microstructure and properties of service components in materials with uneven thermal conductivity due to local microstructure aging or under macroscopic temperature gradients.
temperature gradientphase fieldvoidsmigrationbulk diffusionsurface diffusion
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