Mechanisms for nucleation and propagation of incoherent twins in a CoCrFeNiMo0.15 high-entropy alloy subject to cold rolling and annealing

• Published in: Intermetallics Vol. 96; pp. 104 - 110
• Main Authors: Wu, Wenqian, Wei, Bingqiang, Ni, Song, Liu, Yong, Song, Min
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2018
• Subjects: Annealing twin; Grain boundary; Incoherent twin boundary; Partials; Annealing twin; Incoherent twin boundary; Partials; Grain boundary
• ISSN: 0966-9795
• DOI: 10.1016/j.intermet.2018.03.005

In this paper, the nucleation and propagation mechanisms of annealing twins in a CoCrFeNiMo0.15 high-entropy alloy were systematically studied by high resolution transmission electron microscopy. The study shows direct evidence that the incoherent twin boundaries (ITBs) with large scaled 9R structure can be nucleated at high-angle grain boundaries (GBs) during annealing. Further migration of ITBs leads to the formation of triangular twins bounded by GB, a coherent twin boundary (CTB) and an ITB as their front ends. Several triangular twins with a common (111) plane in the vicinity of GB can merge and then grow to an incoherent twin with steps via the migration of ITBs. At last, a large scaled coherent twin can be formed. Our observation promotes the deep understanding on the formation mechanism of annealing twins in FCC metals and alloys. [Display omitted] •ITBs with large scaled 9R structure can be nucleated at GBs during annealing.•High temperature and low SFE cause the formation of large scaled 9R phase.•Adjacent twins with a common (111) plane in the vicinity of GB can merge together.•The migration of ITBs leads to the formation of an incoherent twin with steps.