Enhancement of solid-state reaction rates by non-hydrostatic stress effects on polycrystalline diffusion kinetics
Enhancement of solid-state reaction rates by non-hydrostatic stress effects on polycrystalline diffusion kinetics
复制标题
通过非静水应力对多晶扩散动力学的影响提高固态反应速率
DOI：
10.2138/am.2010.3372
复制
发表时间：
2010
影响因子：
3.1
通讯作者：
R. Abart
中科院分区：
文献类型：
--
作者：
L. Keller;L. C. Götze;E. Rybacki;G. Dresen;R. Abart
两种化学性质不同的固体之间的反应层生长可以由生长阶段的多晶扩散动力学控制。动力学取决于体积和晶界扩散之间的相互作用。以方镁石和蓝宝石单晶之间形成尖晶石为例，定量研究了机械应力对反应层体输运性质的影响。尖晶石生长的速率增加四倍时，由于应力引起的晶界结构的变化，从3到30 MPa的反应界面的垂直应力增加。在低施加应力下，低折射率（即，3）具有缓慢扩散系数的“重合位置晶格”晶界占主导地位，与尖晶石在蓝宝石上的外延生长有关。应力的增加触发了方镁石上尖晶石的外延生长，并导致尖晶石生长的尖晶石晶粒旋转出外延，并以快速扩散系数的晶界为主。这种影响超过了迄今为止强调的晶粒尺寸对多晶体体输运性质的影响。
Abstract Reaction layer growth between two chemically different solids may be controlled by polycrystalline diffusion kinetics in the growing phase. The kinetics depend on the interplay between volume and grain boundary diffusion. Using spinel formation between single crystals of periclase and sapphire as an example, we quantify the effects of an applied mechanical stress on the bulk-transport properties of the reaction layer. The rate of spinel growth increases fourfold when stress normal to the reaction interface increases from 3 to 30 MPa due to stress-induced changes in grain boundary structure. At low applied stress, low-index (i.e., Σ3) “coincidence site lattice” grain boundaries with slow diffusion coefficients dominate, related to epitactic growth of spinel on sapphire. Increasing stress triggers epitactic growth of spinel on periclase, and causes sapphire-grown spinel grains to rotate out of epitaxy, and grain boundaries with fast diffusion coefficients dominate. This effect outweighs the hitherto emphasized influence of grain size on the bulk transport properties of polycrystals.