Li Peiyou, Wang Yongshan, Meng Fanying, Cao Le, He Zhirong
School of Materials Science and Engineering, Shaanxi University of Technology, Hanzhong 723001, China.
Materials (Basel). 2019 Aug 9;12(16):2539. doi: 10.3390/ma12162539.
The martensitic transformation and superelasticity of TiNi shape memory alloy heat-treatment at different temperatures were investigated. The experimental results show that the microstructures of as-cast and heat-treated (723 K) Ni-rich TiNi samples prepared by rapidly-solidified technology are composed of B2 TiNi phase, and TiNi and TiNi phases; the microstructures of heat-treated TiNi samples at 773 and 823 K are composed of B2 TiNi phase, and of B2 TiNi and TiNi phases, respectively. The martensitic transformation of as-cast TiNi alloy is three-stage, A→R→M and R→M transformation during cooling, and two-stage, M→R→A transformation during heating. The transformations of the heat-treated TiNi samples at 723 and 823 K are the A↔R↔M/A↔M transformation during cooling/heating, respectively. For the heat-treated alloy at 773 K, the transformations are the A→R/M→R→A during cooling/heating, respectively. For the heat-treated alloy at 773 K, only a small thermal hysteresis is suitable for sensor devices. The stable values of 723 and 773 K heat-treated samples with a large value exhibit high safety in application. The 773 and 823 K heat-treated samples have large stable strain-energy densities, and are a good superelastic alloy. The experimental data obtained provide a valuable reference for the industrial application of rapidly-solidified casting and heat-treated TiNi alloy.
研究了不同温度热处理的TiNi形状记忆合金的马氏体相变和超弹性。实验结果表明，采用快速凝固技术制备的铸态和热处理（723K）富Ni的TiNi样品的微观结构由B2 TiNi相、TiNi和TiNi相组成；773K和823K热处理的TiNi样品的微观结构分别由B2 TiNi相、B2 TiNi和TiNi相组成。铸态TiNi合金的马氏体相变是三阶段的，冷却过程中为A→R→M和R→M转变，加热过程中为两阶段，即M→R→A转变。723K和823K热处理的TiNi样品的转变分别是冷却/加热过程中的A↔R↔M/A↔M转变。对于773K热处理的合金，冷却/加热过程中的转变分别是A→R/M→R→A。对于773K热处理的合金，只有小的热滞适合传感器装置。具有大值的723K和773K热处理样品的稳定值在应用中表现出高安全性。773K和823K热处理的样品具有大的稳定应变能密度，是良好的超弹性合金。获得的实验数据为快速凝固铸造和热处理TiNi合金的工业应用提供了有价值的参考。
