( 1. 石油大学 材料科学与工程系, 北京102249;
2. 北京航空航天大学 材料科学与工程系, 北京100083)
摘 要: 研究了TiNi二元与TiNiCu三元形状记忆合金的回复力特征, 并通过示差扫描量热分析研究了合金的热弹性马氏体相变特征。 结果表明: 二元与三元合金在一定温度范围内的最大回复力随着预应变的增大而升高, 但是当预应变达到或超过其最大可恢复变形极限时最大回复力反而减小。 对于TiNi合金, 回复力随温度增长的速率随着预应变的增加而增加, 而TiNiCu合金的回复力随温度增长的速率随着预应变的增加而减小。 通过对克劳修斯-克拉珀龙方程进行修正, 分析了回复力和相变之间的关系。 结果表明: TiNi二元合金的冷变形应变越大, 相变温度区间越小, 其回复力随温度增长的速率就越大; TiNi三元合金的冷变形越大, 相变温度区间越大, 其回复力随温度增长的速率就越小。
关键字: 形状记忆合金; TiNi; TiNiCu; 回复力; 热弹性马氏体相变
( 1. Department of Materials Science and Engineering, University of Petroleum, Beijing 102249, China;
2. Department of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, China)
Abstract: The recovery stress characteristics of TiNi binary and TiNiCu ternary shape memory alloys were studied. Both the maximum recovery stresses of TiNi and TiNiCu alloys increase with increasing prestrain level. The recovery stress rate (dσ/dT) of the TiNi alloy increases with increasing prestrain level, but that of the TiNiCu alloy decreases with increasing prestrain level. By comparing the results of differential scanning calorimetry, analysis based on the modified Clausius-Clapeyron equation shows that the recovery stress characteristics have a close relation to the thermoelastic martensitic transformation characteristics. For TiNi binary alloys, the transformation temperature interval decreases with increasing prestrain level, resulting in the increase of the recovery stress rate. For TiNiCu ternary alloy, the transformation temperature interval increases with increasing prestrain level, resulting in the decrease of the recovery stress rate.
Key words: shape memory alloys; TiNi; TiNiCu; recovery stress; thermoelastic martensitic transformation