Effects of frequency, composition, hydrogen and twin boundary density on the internal friction of Ti50Ni50-xCux shape memory alloys
Effects of frequency, composition, hydrogen and twin boundary density on the internal friction of Ti50Ni50-xCux shape memory alloys
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DOI：
10.1016/j.actamat.2006.06.018
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发表时间：
2006-11-01
期刊：
影响因子：
9.4
通讯作者：
Yin, F.
中科院分区：
文献类型：
--
作者：
Fan, G.;Zhou, Y.;Yin, F.
采用动态力学分析方法对固溶处理后的Ti_（50）Ni_（50-x）Cux多晶的内耗进行了系统的研究。其结果，确认B19马氏体中出现的宽峰为弛豫峰，x = 20时的激活能为0.67 eV，x = 16时的激活能为0.76 eV。如果马氏体中的孪晶界基本消除，那么在单晶实验中宽峰消失。这直接证明了双边界对于宽峰是不可缺少的。氢对IF的影响也使用真空系统与质谱仪，并观察到在250 K的宽峰消失，而一个新的小弛豫峰被发现在178 K，当氢被消除。这些实验清楚地表明，有两个必要的成分来观察高宽峰：孪晶界和氢。基于这些结果，讨论了宽峰的可能来源。(c)2006 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
The internal friction (IF) of Ti50Ni50-xCux polycrystals, which were normally solution-treated, was systematically studied using dynamic mechanical analysis. As a result, the broad peak appearing in B19 martensite was confirmed to be a relaxation peak with an activation energy of 0.67 and 0.76 eV for x = 20 and 16, respectively. Then the broad peak was shown to disappear in a single-crystal experiment, if twin boundaries in martensite are largely eliminated. This is direct evidence to show twin boundaries are indispensable for the broad peak. The effect of hydrogen on IF was also examined using a vacuum system with a mass spectrometer, and the broad peak at 250 K was observed to disappear, while a new small relaxation peak was found at 178 K, when hydrogen was eliminated. These experiments clearly show that there are two essential ingredients to observe the high broad peak: twin boundaries and hydrogen. Based on these results a possible origin for the broad peak is discussed. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.