Twofold role of dislocations in the relaxation behavior of Ti-Ni martensite
Twofold role of dislocations in the relaxation behavior of Ti-Ni martensite
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DOI：
10.1016/j.actamat.2007.10.013
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发表时间：
2008-02-01
期刊：
影响因子：
9.4
通讯作者：
Yin, Fuxing
中科院分区：
文献类型：
--
作者：
Fan, Genlian;Otsuka, Kazuhiro;Yin, Fuxing
Ti-Ni基形状记忆合金中的弛豫峰作为高阻尼源引起了人们的广泛关注，最近的研究表明弛豫峰的起源是孪晶界与氢的相互作用。然而，关于热循环效应的报道，其特征在于峰高随着循环而降低，似乎表明位错也可能影响弛豫行为。为了理解位错在孪晶晶界-氢相互作用峰中的作用，通过动态力学分析系统地研究了含氢和脱氢Ti 50 Ni 50样品的弛豫行为随热循环的变化。结果表明，尽管弛豫峰的起源与位错无关，但位错对孪晶界-氢相互作用过程的影响是相反的。首先，缠结的位错（由热循环产生）使孪晶界运动困难。另一方面，位错也可以从孪晶界吸收氢，使孪晶界运动更容易。动态试验和拉伸试验中的所有热循环效应都可以用位错在孪晶界-氢相互作用过程中的双重作用来解释。(C)2007 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
The relaxation peak in Ti-Ni-based shape memory alloy, is attracting much attention a, a high damping source, and it, origin was recently revealed to be the interaction between twin boundaries and hydrogen. However, reports on the thermal cycling effect, which is characterized by the peak height decrease with cycling, seem to suggest that dislocations may also affect the relaxation behavior. To understand the role of dislocations in the twin boundary-hydrogen interaction peak, changes in the relaxation behavior with thermal cycling were systematically studied by dynamical mechanical analysis for both H-containing and dehydrogenated Ti50Ni50 samples. Our results show that although the origin of the relaxation peak is not related with dislocations, dislocations can affect the twin boundary-hydrogen interaction process in two opposite ways. First, tangled dislocations (created by thermal cycling) make twin boundary motion difficult. On the other hand, dislocations can also absorb hydrogen from twin boundaries and make twin boundary motion easier. All the thermal cycling effects in dynamic tests and de tensile tests can be explained by the above dual role of dislocations in the twin boundary-hydrogen interaction process. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.