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Martensitic Transformation and its Composition Dependence in Ti-Ni-Cu Shape Memory Alloys

Ti-Ni-Cu 形状记忆合金中的马氏体相变及其成分依赖性

基本信息

批准号：
16560584
负责人：
OTSUKA Kazuhiro
金额：
$ 2.37万
依托单位：
Foundation for Advancement of International Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16560584/
关键词：
shape memory alloy martensitic transformation Ti-Ni-Cu alloy synchrotron radiation high damning material internal friction twin hydrogen 2段変態

项目摘要

Ti_<50>Ni_<50-x>Cu_x alloys attract much attention recently as vibration-proof materials with high internal friction. These alloys show 2-stage B2-B19(orthorhombic)-B19'(monoclinic) martensitic transformation for 10=x=15, but it is not clear whether they show 2-stage transformation for x>15 or not. Meanwhile, the head researcher previously found that for x>15 the alloys show very high internal friction peak (Q^<-1>=0.2) called "broad peak" at around 250K. In order to understand the origin of the broad peak, it is inevitable to understand the characteristics of the martensitic transformation of the alloys including the compositions x>15.For this purpose we carried out x-ray diffraction experiments with extremely high intensity at synchrotron facilities (SPring-8). Consequently we confirmed the 2^<nd> stage transformation also occurs for x>15, and we could determine the transformation temperatures. Furthermore, very peculiar characteristics were found such that only a very small fraction … More of specimens show the 2^<nd> transformation for 12=x=20. From these results it became possible to separate multiple internal friction peaks. Thus we carried out detailed internal friction experiments using DMA. Consequently we confirmed that the broad peak is a relaxation peak with the following activation energies ; E=0.67eV(x=20),E=0.76eV (x=16). Furthermore, by carrying out single crystal experiments, we found that the broad peak disappears if twins are eliminated by tensile stress. This is a direct evidence to show twins are necessary to observe the broad peak. Meanwhile, there are some reports that hydrogen is necessary to observe the broad peak. By carrying out de-hydrogenation experiments we also confirmed that the broad peak disappear by de-hydrogenation. From these experiments we can conclude that both twin boundaries and H are necessary to observe the high broad peak. Furthermore, we found that a new relaxation peak appears at around 178K after de-hydrogenation. These results are now submitted to Acta Materialia including the discussion of the origin of the broad peak. Less

Ti_<50>Ni_<50-x>Cu_x合金作为高内耗的防振材料近年来备受关注。这些合金在 10=x=15 时表现出 2 阶段 B2-B19（斜方）-B19'（单斜）马氏体转变，但尚不清楚它们是否在 x>15 时表现出 2 阶段转变。同时，首席研究员此前发现，对于x>15，合金在250K左右表现出非常高的内耗峰值（Q^<-1>=0.2），称为“宽峰”。为了了解宽峰的起源，必须了解包括成分x>15的合金的马氏体转变特征。为此，我们在同步加速器设施（SPring-8）上进行了极高强度的X射线衍射实验。因此，我们确认 x>15 时也会发生第 2^<nd> 阶段转变，并且我们可以确定转变温度。此外，还发现了非常奇特的特征，只有极少数样本显示 12=x=20 的 2^<nd> 变换。根据这些结果，可以分离多个内耗峰值。因此我们使用 DMA 进行了详细的内耗实验。因此我们确认宽峰是具有以下活化能的弛豫峰； E=0.67eV（x=20），E=0.76eV（x=16）。此外，通过进行单晶实验，我们发现如果通过拉应力消除孪晶，宽峰就会消失。这是表明双胞胎必须观察宽峰的直接证据。同时，有一些报道称氢对于观察宽峰是必需的。通过进行脱氢实验，我们还证实宽峰因脱氢而消失。从这些实验中我们可以得出结论，孪晶边界和 H 对于观察高宽峰都是必要的。此外，我们发现脱氢后在178K左右出现了新的弛豫峰。这些结果现已提交给 Acta Materialia，包括宽峰起源的讨论。较少的