论文标题
氢吸收和解吸过程中的脱位愈合
Dislocation healing during hydrogen absorption and desorption in palladium
论文作者
论文摘要
对散装PD-D2系统中位错的退火和愈合的原位中子衍射研究进行了研究。 Alpha和Beta氢化物相之间的晶格失配在两个方向上的相变时会产生脱位，从而缓解了弹性滞后时的弹性应变，与Spinodal滞磁滞相比，这反映在降低的压力磁滞中。通过测量退火和氢气循环过程中的衍射峰值宽度，研究了对真空中退火，在β氢化物相中退火和相变的脱离金属的影响。在真空下退火期间，在温度低的温度下除去了位错，但是在β期间退火给出了几乎相同的结果。但是，与退火相比，当循环氢进出样品时，随着温度的升高，脱位密度降低了得多。换句话说，相变的过程可以在较低的温度下愈合位错的愈合，而不是通过加热而纯粹通过加热来恢复脱位。在吸收和解吸过程中都观察到这种愈合效果。该结果阐明了与在经历吸收解吸循环的样品中相同的速率治愈失位的机制，如压力滞后的起源的理论模型所提出的那样。
An in-situ neutron diffraction investigation of the annealing and healing of dislocations in the bulk Pd-D2 system was carried out. Lattice misfit between the alpha and beta hydride phases produces dislocations during the phase transition in either direction, relieving elastic strain, which is reflected in reduced pressure hysteresis compared to the spinodal hysteresis. The effects on the dislocation density of annealing the metal under vacuum, of annealing in the beta hydride phase, and of the phase transformation itself were investigated by measuring diffraction peak breadths during annealing and hydrogen cycling. During annealing under vacuum the dislocations were removed at a lower temperature than was previously reported, but annealing in the beta phase gave nearly the same result. However, when cycling hydrogen in and out of the sample, the dislocation density decreased much faster with increasing temperature compared to annealing. In other words the process of phase transformation allows for healing of dislocations at lower temperatures than would be required to anneal them purely by heating. This healing effect was observed during both absorption and desorption. This result illuminates the mechanism by which misfit dislocations can be healed at the same rate that they are created in a sample undergoing absorption-desorption cycling, as proposed in theoretical models of the origin of pressure hysteresis.
