| The Two-step Reverse Martensitic Transformations of TiNi Shape Memory Alloy Based on Solution-treatment and Aging |
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| 作者姓名： | JIANG Da-qiang CUI Li-shan* ZHENG Yan-jun JIANG Xiao-hua |
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| 作者单位： | JIANG Da-qiang，CUI Li-shan*，ZHENG Yan-jun，JIANG Xiao-hua Department of Materials Science and Engineering，China University of Petroleum，Beijing 102249，China |
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| 摘 要： | A TiNi-alloy is solution-treated in a vacuum furnace of 6.7×10-3 Pa at 1 223 K for 3.6 ks, and then aged at 773 K for 1.8 ks. The differential scanning calorimetry (DSC) measurements show that after the heat-treatment, takes place a two-step reverse Martensitic transformation, from which results the two-stage recovery strain in a prestrained Martensitic TiNi-alloy wire during heating. The Vickers microhardness indentation test in cross-sectional areas of the TiNi-alloy wire indicates the compositional heterogeneity between its sur-face layers and its inside. The fact that the sizes of the indentation in surface layers smaller than those in the inside bears witness to the existence of slightly harder surface layers. It is believed that these phenomena are related to the compositional fluctuation caused by the evaporation and oxidization of Ti-element during the solution-treatment and heterogeneity formed during the subsequent aging treat-ment.
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The Two-step Reverse Martensitic Transformations of TiNi Shape Memory Alloy Based on Solution-treatment and Aging |
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| JIANG Da-qiang,CUI Li-shan*,ZHENG Yan-jun,JIANG Xiao-hua.The Two-step Reverse Martensitic Transformations of TiNi Shape Memory Alloy Based on Solution-treatment and Aging[J].Chinese Journal of Aeronautics,2006,19(Z1). |
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| Authors: | JIANG Da-qiang CUI Li-shan ZHENG Yan-jun JIANG Xiao-hua |
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| Abstract: | A TiNi-alloy is solution-treated in a vacuum furnace of 6.7×10-3 Pa at 1 223 K for 3.6 ks, and then aged at 773 K for 1.8 ks. The differential scanning calorimetry (DSC) measurements show that after the heat-treatment, takes place a two-step reverse Martensitic transformation, from which results the two-stage recovery strain in a prestrained Martensitic TiNi-alloy wire during heating. The Vickers microhardness indentation test in cross-sectional areas of the TiNi-alloy wire indicates the compositional heterogeneity between its surface layers and its inside. The fact that the sizes of the indentation in surface layers smaller than those in the inside bears witness to the existence of slightly harder surface layers. It is believed that these phenomena are related to the compositional fluctuation caused by the evaporation and oxidization of Ti-element during the solution-treatment and heterogeneity formed during the subsequent aging treatment. |
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| Keywords: | shape memory alloy (SMA) TiNi solution-treatment heterogeneity |
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