A simultaneous deformation and diffusion experiment: Quantifying the role of deformation in enhancing metamorphic reactions
A simultaneous deformation and diffusion experiment: Quantifying the role of deformation in enhancing metamorphic reactions
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同时变形和扩散实验：量化变形在增强变质反应中的作用
DOI：
10.1016/j.epsl.2008.12.026
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发表时间：
2009
影响因子：
5.3
通讯作者：
C. McCammon
中科院分区：
文献类型：
--
作者：
F. Heidelbach;M. Terry;M. Bystricky;C. Holzapfel;C. McCammon
在300 MPa和1523 K的扭转实验中，研究了同步塑性变形对铁镁钙/方镁钙连续交换反应的影响，并将其作为应变和微观结构变化的函数。随着剪切应变（γ = 5.2）、应变速率（≥2.9×10−4s−1）和晶粒尺寸（从200 μm减小到80 μm）的增加，Fe-Mg相互扩散系数呈1.2 ~ 1.4的非线性增加（取决于成分）。扩散系数的变化主要是由于大角度晶界（>15°）密度的增加，而亚晶界密度和位错密度与扩散系数的变化关系不大。由于晶界扩散而增加的扩散率并不符合所提出的体积和边界扩散的组合方程，这表明晶界扩散的影响被低估了，或者由于晶内变形（位错和/或点缺陷的移动）对扩散率有额外的影响。动态再结晶过程中的晶界迁移)，即使在扩散方向上没有净应力或应变。
The influence of concurrent plastic deformation on a continuous Fe–Mg exchange reaction in ferropericlase/periclase was examined as a function of strain and changing microstructure in a torsion experiment performed at 300 MPa and 1523 K. The measured Fe–Mg interdiffusion coefficient increases non-linearly by a factor of 1.2 to 1.4 (depending on composition) with increasing shear strain (up to a γ of 5.2), strain rate (up to 2.9×10−4s−1) and decreasing grain size (from 200 μm to 80 μm). The change in diffusion is attributed to the increase in density of large-angle (>15°) grain boundaries, whereas both subgrain boundary density and dislocation density do not correlate well with the changing diffusion coefficients. The increased diffusivity due to grain boundary diffusion does not follow any of the proposed equations for combined volume and boundary diffusion, indicating that either the effect of grain boundary diffusion has been underestimated or that there is an additional effect on diffusivity due to intracrystalline deformation (movement of dislocations and/or point defects, grain boundary migration during dynamic recrystallization) even if there is no net stress or strain in the direction of diffusion.