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The contrasting fracture behaviour of twin boundaries and general boundaries – A first principles study based on experimental observation
Materials Science and Engineering: A ( IF 6.1 ) Pub Date : 2020-03-10 , DOI: 10.1016/j.msea.2020.139225
Reza Mahjoub , Dudekula Althaf Basha , Alok Singh , Michael Ferry , Nikki Stanford

Experimental observations of grain boundary fracture behavior have been used as exemplars, and boundaries with the same crystallography as the experiments were developed. These boundaries were non-symmetrical, and this necessitated the first ever study of non-symmetrical boundaries in magnesium using density functional theory The broad agreement of the calculated boundary cohesion values with the experimental observations of fracture behavior showed the simulations to be good approximations of real behavior, and from this point the simulations were further interrogated to understand the differences between the boundary types and solute species. Solutes with both larger and smaller radii than magnesium had a preference for segregation to the grain boundary. The boundary cohesion was examined by the parameter known as embrittlement potency, and it was found that solutes smaller than magnesium had a toughening effect, while those solutes larger than magnesium had more tendency to embrittle. The two boundaries studied in most detail, the {101¯2} twin boundary, and a general grain boundary observed experimentally, showed different cohesive behaviors. Although the symmetrical twin boundary behaved in a similar manner to previous reports, the non-symmetrical boundary showed more complex cohesive behavior, highlighting the importance of studying the non-symmetrical boundaries the predominate real materials.



中文翻译:

孪晶边界和一般边界的对比断裂行为–基于实验观察的第一性原理研究

晶界断裂行为的实验观察已被用作示例,并开发了与实验具有相同晶体学的晶界。这些边界是非对称的,因此有必要使用密度泛函理论对镁中的非对称边界进行首次研究。计算得出的边界内聚力值与断裂行为的实验观察结果的广泛一致性表明,该模拟与真实情况近似良好。行为,从这一点出发,进一步模拟以了解边界类型和溶质种类之间的差异。半径大于和小于镁的溶质优先偏析到晶界。边界凝聚力通过称为脆化力的参数进行检查,并且发现,小于镁的溶质具有增韧作用,而大于镁的溶质具有更大的脆化趋势。对两个边界进行了最详细的研究,{101个¯2}实验观察到的孪晶边界和一般的晶界表现出不同的内聚行为。尽管对称孪晶边界的行为与以前的报告相似,但非对称边界表现出更复杂的内聚行为,突显了研究以非对称边界为主的真实材料的重要性。

更新日期:2020-03-10
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