Interface pinning causes the hysteresis of the hydride transformation in binary metal hydrides
Interface pinning causes the hysteresis of the hydride transformation in binary metal hydrides
复制标题
界面钉扎导致二元金属氢化物中氢化物转变的滞后
DOI：
10.1103/physrevmaterials.5.013604
复制
发表时间：
2021
影响因子：
3.4
通讯作者：
Fultz, Brent
中科院分区：
文献类型：
--
作者：
Weadock, Nicholas J.;Voorhees, Peter W.;Fultz, Brent
采用Pd-H模型体系，通过原位X射线衍射法测量压力-组成等温线，研究了块体和纳米晶二元金属氧化物的氢化和放氢转变。纳米晶Pd表现出较小的压力滞后，固溶线滞后，和滞后的晶格参数相比，散装Pd。压力平衡的时间依赖性的测定后，与等份的氢给药，得到的平衡时间，是快得多的单相区域比在两相平台。在宽的两相平台区，压力弛豫与时间呈指数函数关系。滞后的解释是基于一个耗散的势垒，阻碍了由于晶格缺陷和两相界面之间的相互作用的界面的运动。指数压力松弛和滞后是一致的，这种机制。对于一个简单的模型的钉扎电位，势垒的最大值是一个数量级小于典型的晶界能量。这些钉扎效应在纳米晶Pd中是实质上不同的，这表明在钉扎机制中的差异。
Hydriding and dehydriding transitions in bulk and nanocrystalline binary metal hydrides were studied using the Pd-H model system by measuring pressure-composition isotherms within situx-ray diffractometry. Nanocrystalline Pd showed a smaller pressure hysteresis, solvus hysteresis, and hysteresis in lattice parameter, compared to bulk Pd. The time-dependence of pressure equilibration was measured after dosing with aliquots of hydrogen, giving equilibration times that were much faster in the single-phase regions than in the two-phase plateaus. In the broad two-phase plateaus, the pressure relaxations were exponential functions of time. An explanation of hysteresis is developed that is based on a dissipative potential barrier that impedes the motion of the interface due to interactions between lattice defects and the two-phase interface. The exponential pressure relaxations and hysteresis are consistent for this mechanism. For a simple model of the pinning potential, the potential barrier maximum is an order of magnitude less than typical grain boundary energies. These pinning effects are substantially different in the nanocrystalline Pd, suggesting differences in the hydriding mechanism.