热处理温度对TiNiCuCo合金的力学性能和形状记忆效应的影响

Effects of Heat Treatment Temperature on Mechanical Properties and Shape Memory Effect of TiNiCuCo Alloy

通过真空感应熔炼制备TiNiCuCo形状记忆合金铸锭,然后经锻造、轧制、热拉拔得到准0.5mm的线材,最后对线材进行300~700℃退火。通过拉伸试验和弯曲回复法等研究了不同温度热处理后TiNiCuCo合金的力学性能和形状记忆效应。结果表明在300~500℃进行热处理,TiNiCuCo合金的抗拉强度和伸长率几乎不发生变化;在600~700℃进行热处理,其抗拉强度显著降低,伸长率显著增大。随着热处理温度的升高,平台应力先减小再增大。在热处理温度为500℃时平台应力最小,为32MPa。平台应变在300~400℃热处理几乎不发生变化,最大值为6.8%。随着热处理温度的升高,平台应变逐渐减小,700℃时平台应变为3.5%。TiNiCuCo合金在300~500℃热处理后具有良好的形状记忆效应;6%~8%弯曲应变后,合金的最大形状回复率可达96%以上。高于500℃进行热处理,合金的最大形状回复率降低。TiNiCuCo合金对温度的响应程度几乎不随热处理温度发生变化。

The shape memory alloy TiNiCuCo ingots were prepared by vacuum induction melting, and the 0.5 mm wire was obtained after forging, rolling and hot drawn. Finally, the wire was annealed at 300-700℃. Mechanical properties and shape memory effect of TiNiCuCo alloy after heat treatment at different temperatures were studied by tensile test and bending recovery method. The results show that the tensile strength and the elongation of TiNiCuCo alloy almost have no change with the increase of heat treatment temperature fi＇om 300 to 500℃. When the alloy is heat treated in 600-700℃, the tensile strength significantly decreases and the elongation significantly increases. With the increase of heat treatment temperature, the plateau stress decreases first and then increases. When the temperature is 500℃, the plateau stress is minimum, which is 32 MPa. The plateau strain almost has no change with the increase of heat treatment temperature in the range of 300-400℃ and the maximum value is 6.8%. With the increase of heat treatment temperature, the plateau strain decreases gradually and when the temperature is 700℃, its value is 3.5%. TiNiCuCo alloy has good shape memory effect after heat treatment at 300-500℃ and the maximum shape recovery ratio of the alloy can reaches above 96% after 6%-8% bending deformation. When the heat treatment temperature exceeds 500℃, the maximum shape recovery ratio of the alloy decreases. The temperature response of TiNiCuCo changes hardly with the heat treatment temperature.