Hydrogen embrittlement behavior induced by dynamic martensite transformation of Ni–Ti superelastic alloy
Hydrogen embrittlement behavior induced by dynamic martensite transformation of Ni–Ti superelastic alloy
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DOI：
10.1016/j.actamat.2008.12.030
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发表时间：
2009-04
期刊：
影响因子：
9.4
通讯作者：
K. Yokoyama;Miho Tomita;J. Sakai
中科院分区：
文献类型：
--
作者：
K. Yokoyama;Miho Tomita;J. Sakai
采用氢热解吸分析方法研究了Ni-Ti超弹性合金经氢阴极充电动态循环拉伸试验后马氏体相变引起的氢脆行为。随着变形循环次数的增加，马氏体相变的临界应力急剧降低，而相反相变的临界应力变化不大。与马氏体相本身相比，动态应力诱导的马氏体相变显著增强了氢的吸收。样品表层的氢浓度估计在3500mass sppm以上；然而，没有发生与应力诱导马氏体转变相关的断裂。此外，尽管氢化物的形成和氢的富集，在试样的表层未观察到硬化。低温热解吸氢明显增多，表明氢态发生了动态马氏体相变。注意氢和相变之间的相互作用可能是不可逆的，尽管相变是可逆的。本研究首次表明，合金的氢脆行为强烈依赖于伴随马氏体相变的氢态动态变化。
The hydrogen embrittlement behavior induced by the martensite transformation of Ni–Ti superelastic alloy subjected to a dynamic cyclic tensile test with hydrogen cathodic charging has been investigated by hydrogen thermal desorption analysis. The critical stress for the martensite transformation steeply decreases with increasing number of deformation cycles, whereas the critical stress for the reverse transformation only slightly changes. The dynamic stress-induced martensite transformation markedly enhances hydrogen absorption, compared with that of the martensite phase itself. The hydrogen concentration at the surface layer of the specimen is evaluated to be above 3500massppm; nevertheless, no fracture associated with the stress-induced martensite transformation occurs. In addition, no hardening is observed at the surface layer of the specimen despite the formation of the hydride and hydrogen enrichment. The hydrogen thermally desorbed at a low temperature markedly increases, indicating that the hydrogen states are changed by the dynamic martensite transformation. Note that interactions between hydrogen and the phase transformation are probably irreversible, although the phase transformation is reversible. The present study shows, for the first time, that the hydrogen embrittlement behavior of the alloy strongly depends on the dynamic change of the hydrogen states accompanied by the martensite transformation.