金属间化合物不稳定机制:位错攀爬-滑移-原子重排

     金属间析出物被广泛应用于调控合金的力学性能,但其在合金塑性变形过程中常常不够稳定,如何避免这种情况出现着实是一种挑战。

     来自中国西安交通大学的Qing Zhou团队及其美国合作伙伴,采用分子动力学模拟,研究了铝-铜合金变形过程中金属间析出物位错的相互作用。他们的研究表明,非共面<001>位错偶极子在塑性变形过程中出现了异常相互作用:非共面<001>位错出现了攀爬(而非传统意义上的滑移),之后再沿新的原子平面集体滑移,出现了大规模原子重排(atomic shuffle),位错并没有相互抵消,反而产生了空穴。——这便造成了Al2Cu金属间析出物的结构不稳定。温度升高,缺陷产生加快,位错核心得以扩展,空穴簇也变得更大,析出物也会加速溶解。该研究通过原子尺度模拟阐明了Al2Cu模型系统中与位错运动相关的金属间析出物的结构不稳定机制,有可能帮助避免采用析出物强化合金时出现的失效,也有助于探索其它非立方金属间化合物的塑性变形不稳定机制。该文近期发表于npj Computational Materials 3: 24 (2017);  doi:10.1038/s41524-017-0030-2


标题与摘要如下:



Dislocations interaction induced structural instability in intermetallic Al2Cu 

(金属间化合物Al2Cu中位错相互作用诱导结构不稳定性行为)


Qing Zhou, Jian Wang, Amit Misra, Ping Huang, Fei Wang & Kewei Xu

     Intermetallic precipitates are widely used to tailor mechanical properties of structural alloys but are often destabilized during plastic deformation. Using atomistic simulations, we elucidate structural instability mechanisms of intermetallic precipitates associated with dislocation motion in a model system of Al2Cu. Interaction of non-coplanar <001> dislocation dipoles during plastic deformation results in anomalous reactions—the creation of vacancies accompanied with climb and collective glide of <001> dislocation associated with the dislocation core change and atomic shuffle—accounting for structural instability in intermetallic Al2Cu. This process is profound with decreasing separation of non-coplanar dislocations and increasing temperature and is likely to be operative in other non-cubic intermetallic compounds as well.




原文链接:https://www.nature.com/articles/s41524-017-0030-2


原文下载:/upload/201708/31/201708311150532750.pdf




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