A simulation study of the distribution of beta ' precipitates in a crept Mg-Gd-Zr alloy

作者：Liu, H.; Xu, W. F.; Peng, L. M.^*; Ding, W. J.; Nie, J. F.^*

来源：Computational Materials Science, 2017, 130: 152-164.

DOI：10.1016/j.commatsci.2016.12.021

• Magnesium alloys
• Precipitate
• Creep
• Applied stress
• Dislocation
• Phase field

A linear chain distribution of beta' precipitates is found in a Mg-2.4Gd-0.1Zr (at.%) alloy crept at 250 degrees C for 155 h or longer under a uniform tensile stress in a range of 80-120 MPa, which is distinctly different from the random distribution of beta' precipitates in the same alloy before creep tests. In this work, the influences of the applied stress and dislocations on the distribution of beta' precipitates and the formation of the linear precipitate chains are investigated via the interaction energy calculation and phase field simulation. Our calculation and simulation results indicate that the applied stress promotes the preferential growth of one of the three beta' variants during coarsening. The applied stress can also activate the gliding and climbing of dislocations during creep. Among these dislocations, the alpha-type basal edge dislocations are most likely to act as heterogeneous nucleation sites for beta' precipitates. Compared with the other two variants, the variant that has zig-zag monolayers of Gd atoms perpendicular to the dislocation line is more favourable to nucleate and grow along the dislocation line and form precipitate chains. This variant is also the one favoured by the applied stress.

• 出版日期2017-4-1
• 单位上海交通大学