From coherent to semicoherent-Evolution of precipitation crystallography in an fcc/bcc system
From coherent to semicoherent-Evolution of precipitation crystallography in an fcc/bcc system
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从相干到半相干 — fcc/bcc 系统中沉淀晶体学的演变
DOI：
10.1016/j.actamat.2019.12.057
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发表时间：
2020
期刊：
影响因子：
9.4
通讯作者：
Zhang Wen-Zheng
中科院分区：
文献类型：
--
作者：
Dai Fu-Zhi;Sun Zhi-Peng;Zhang Wen-Zheng
各向异性失配的相变系统(例如，bcc/fcc系统)中的结晶学特征是如何发展的？对这一问题的全面认识仍然非常有限，这阻碍了对微观组织演化的深入理解和定量建模。在这项工作中，我们用蒙特卡罗和分子动力学相结合的方法模拟了铬沉淀(Bcc)在铜基(Fcc)中的早期生长过程。模拟结果揭示了晶体特征演化的细节，包括两相之间的取向关系(OR)、沉淀形态和界面位错结构。演化过程中的主导事件是一组占主导地位的位错的产生。主要位错的选择是基于主面内界面能最小化的基础上的，主要面内只有一组位错。共格沉淀与基质的初始OR接近于Nishiyama-Wassermann OR。响应于主要位错的产生，OR向对应于O线状态的理想OR跳跃，其接近Kurdjuov-Sachs OR。这一趋势反映了在铜-铬系统中的实验观察，并为了解晶体特征的实际演变提供了有益的见解。
How are crystallographic features developed in phase transformation systems with anisotropic misfits (e.g., bcc/fcc systems)? Comprehensive knowledge about this question is still very limited, which impedes the thorough understanding and the quantitative modeling of microstructure evolution. In this work, we simulated the early stage growth of a Cr precipitate (bcc) in a Cu matrix (fcc) by combining Monte Carlo and molecular dynamics. The simulation results reveal fine details about the evolution of crystallographic features, including the orientation relationship (OR) between the two phases, the precipitate morphology, and the interfacial dislocation structures. The governing event during the evolution process is the generation of a dominant set of dislocations. The selection of the dominant dislocations is rationalized based on minimization of the interfacial energy in the major facet, which contains a single set of dislocations. The initial OR between the coherent precipitate and the matrix is close to the Nishiyama–Wassermann OR. In response to the generation of the dominant dislocations, the OR jumps towards the ideal OR corresponding to the O-line condition, which is close to the Kurdjumov–Sachs OR. This tendency reflects the experimental observations in a Cu-Cr system and provides helpful insight into the actual evolution of crystallographic features.