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首页> 外文期刊>Physics of the Earth and Planetary Interiors: A Journal Devoted to Obsevational and Experimerntal Studies of the Chemistry and Physics of Planetary Interiors and Their Theoretical Interpretation >The influence of anisotropic diffusion on the high-temperature creep of a polycrystalline aggregate
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The influence of anisotropic diffusion on the high-temperature creep of a polycrystalline aggregate

机译：各向异性扩散对多晶骨料高温蠕变的影响

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摘要

The influence of anisotropic diffusion coefficients on diffusion-controlled high-temperature creep is examined. Anisotropic diffusion affects anisotropy of diffusion-controlled deformation of a single crystal. The shape change of a single crystal by diffusional mass flux is controlled directly by the anisotropy in diffusion coefficients. The rate of shape change of a single crystal by diffusion-controlled dislocation glide is controlled by the anisotropy of diffusion coefficients on the plane normal to the dislocation line. Consequently, if a polycrystalline aggregate is deformed uniformly by diffusion creep, then the rate of deformation is controlled by that of diffusion (of the slowest diffusion species) along the slowest direction. In contrast, when a polycrystalline aggregate is deformed by climb-controlled dislocation creep, the rate of deformation is controlled by the diffusion (of the slowest diffusion species) along the direction where the diffusion coefficient has the intermediate value. The results are applied to olivine and post-perovskite. For olivine, the observed large plastic anisotropy and small anisotropy in diffusion suggests that high-temperature power-law creep is controlled not only by diffusion but also by some other factors such as jog density. For post-perovskite, the results of numerical calculations on the mobility of vacancies would suggest that the viscosity of post-perovskite aggregates is higher than or comparable to that of the perovskite aggregates if the defect concentrations were the same among these minerals. However, currently nothing is known about the defect concentrations in post-perovskite and other coexisting phases, and therefore it is impossible to compare the creep strength among coexisting phases from these results.
机译：研究了各向异性扩散系数对扩散控制的高温蠕变的影响。各向异性扩散影响单晶的扩散控制变形的各向异性。由扩散质量通量引起的单晶形状变化直接由扩散系数的各向异性控制。由扩散控制的位错滑行引起的单晶形状变化的速率受与位错线垂直的平面上扩散系数的各向异性控制。因此，如果多晶聚集体由于扩散蠕变而均匀地变形，则变形速率由沿最慢方向的扩散速率（最慢扩散物种的速率）控制。相反，当多晶聚集体由于爬升控制的位错蠕变而变形时，变形率由（最慢扩散种类的）沿着扩散系数具有中间值的方向的扩散来控制。该结果适用于橄榄石和钙钛矿后。对于橄榄石，观察到的较大的塑性各向异性和较小的扩散各向异性表明，高温幂律蠕变不仅受扩散控制，还受诸如点动密度等其他因素的控制。对于钙钛矿后，空位迁移率的数值计算结果表明，如果这些矿物中的缺陷浓度相同，则钙钛矿后聚集体的粘度高于或与钙钛矿后聚集体的粘度相当。但是，目前对钙钛矿后阶段和其他共存相中的缺陷浓度一无所知，因此无法根据这些结果来比较共存相之间的蠕变强度。

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