The effect of HCP on the formation of twin boundaries and dislocations in Ni–Co alloys

• Published in: Current applied physics 2021, 29(0), , pp.18-23
• Main Authors: Ma, Rui-bo, Zhou, Li-li, Liang, Yong-chao, Chen, Qian, Tian, Ze-an, Liu, Rang-su, Mo, Yun-fei, Gao, Ting-hong, Xie, Quan
• Format: Article
• Language: English
• Subjects: Dislocation; Molecular dynamics; Ni–Co alloys; Twin boundary; 물리학
• ISSN: 1567-1739; 1878-1675
• DOI: 10.1016/j.cap.2021.05.012

In this study, molecular dynamics (MD) was used to simulate the rapid solidification process of Ni47Co53 and Ni48Co52 alloys at a cooling rate of 1012 K/s. The effects of HCP on the formation of twin boundaries and dislocations in two Ni–Co alloys are studied. It is found that the difference of HCP clusters is the main effect that producing discrepancies on microstructure of two alloys. The number of HCP clusters accounted for 9.23% in Ni47Co53 alloy. They are regularly arranged to form the number of single-layer twin boundaries, and each twin boundary ends in a dislocation. The FCC and HCP structures coexist in the same atomic layers, which is easy to create dislocations. The relatively standard FCC crystal and only 0.32% HCP clusters are formed in Ni48Co52 alloy at 300 K. That small amount of HCP clusters are dispersed on the surface, and cause the formation of dislocation in the border with FCC clusters. •Ni47Co53 undergoes only one phase transition, while Ni48Co52 undergoes two phase transitions.•HCP with a proportion of 9.23% are formed in Ni47Co53, but only 0.32% HCP are formed in Ni48Co52.•The connection modes are mostly FCC-FCC and FCC-HCP in Ni47Co53, while almost only FCC-FCC are formed in Ni48Co52.•HCP is arranged in a single layer to form twin boundaries in Ni47Co53, but HCP is dispersed on the surface in Ni48Co52.