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The influence of large second phase grains on microstructural evolution during diffusion creep
Journal of Structural Geology ( IF 3.1 ) Pub Date : 2021-05-13 , DOI: 10.1016/j.jsg.2021.104371
Joe Gardner , John Wheeler

Diffusion creep is a fundamental mechanism by which Earth materials deform, but the way microstructure evolves during diffusion creep remains poorly understood, because the mechanism does not leave behind abundant microstructural indicators. Because most rocks are polyphase, this study used numerical simulations to investigate the influence of large second-phase grains on the microstructural evolution of a fine-grained matrix during diffusion creep in both pure and simple shear. The results of the modelling show that large second-phase grains create stress heterogeneities that focus the effects of diffusion creep, which can lead to a profound drop in strength of a material, and dictate where grain boundary sliding surfaces develop within the fine-grained matrix. Rotations of matrix grains are strongly influenced by the rotation direction and velocity of the large grain, especially those that lie adjacent to it. The rotation direction of large grains is not simply either synthetic or antithetic to the shear direction. Instead, rotation directions of large grains can change due to interactions with the matrix. Such interactions could result in simple strain paths producing complex microstructures which could be misinterpreted to record much more complicated strain histories.



中文翻译:

大第二相晶粒对扩散蠕变过程中微观组织演变的影响

扩散蠕变是地球材料变形的基本机制,但是对于扩散蠕变期间微结构的演化方式仍然知之甚少,因为该机制并未留下大量的微结构指标。因为大多数岩石是多相的,所以本研究使用数值模拟研究了在纯剪切和简单剪切过程中扩散蠕变过程中大的第二相晶粒对细晶粒基体组织演变的影响。建模结果表明,较大的第二相晶粒会产生应力异质性,这些异质性集中于扩散蠕变的影响,这会导致材料强度急剧下降,并决定晶粒边界滑动面在细晶粒基体中的何处发展。基体晶粒的旋转受到大晶粒(尤其是与其相邻的晶粒)的旋转方向和速度的强烈影响。大晶粒的旋转方向不只是剪切方向的合成方向或与之相反的方向。相反,由于与基体的相互作用,大晶粒的旋转方向可能会发生变化。这种相互作用可能导致简单的应变路径产生复杂的微观结构,而这些微观结构可能会被曲解以记录更为复杂的应变历史。

更新日期:2021-05-25
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