(陕西理工大学 材料科学与工程学院，汉中 723001)
摘 要: 对Ti-50.8Ni-0.1Zr(摩尔分数，%)形状记忆合金进行了800 ℃固溶淬火+(300~600 ℃, 1~50 h)时效处理，采用光学显微镜、透射电镜和差示扫描量热仪研究了时效温度和时效时间对该合金显微组织和相变行为的影响。结果表明：随时效温度升高，合金中Ti3Ni4析出相由细小颗粒状生长为透镜状再变为粗片状。300 ℃时效态合金的相变类型为A→R→M/M→R→A(A为母相B2，CsCl型结构；M为马氏体B19′，单斜结构；R为R相，菱方结构)，400 ℃时效态合金的相变类型由A→R→M/M→R→A向A→R→M/M→A型转变，500 ℃和600 ℃时效态合金的相变类型分别为A→R→M/M→A和A→M/M→A。随时效温度升高，该合金的R、M相变温度先升高后降低，400 ℃、50 h时效态合金的R相变温度最大(为43.7 ℃)，500 ℃、50 h时效态合金的M相变温度最大(为4.0 ℃)；M相变热滞在26.1~122.6 ℃之间变化；R相变热滞比较稳定，在4.8~7.5 ℃之间变化。随时效时间延长，该合金的R、M相变温度先升高后趋于稳定，M相变热滞先降低后趋于稳定，R相变热滞变化不大。时效温度对Ti-50.8Ni-0.1Zr合金析出相形貌和相变行为的影响比时效时间更显著。
关键字: Ti-50.8Ni-0.1Zr合金；形状记忆合金；时效工艺；显微组织；相变行为
（School of Materials Science and Engineering, Shaanxi University of Technology, Hanzhong 723001, China）
Abstract:The heat treatments of solution-quenched at 800 ℃ + aged at 300-600 ℃ for 1-50 h were carried out in Ti-50.8Ni-0.1Zr (mole fraction) shape memory alloy, the effects of aging temperature and aging time on the microstructure and phase transformation behaviors of the alloy were investigated by optical microscopy, TEM, and differential scanning calorimetry. With the increase of aging temperature, the morphologies of Ti3Ni4 precipitates in the alloy change from the fine particle to the lenticular, and then to the thick plate. The phase transformation type of the alloy aged at 300 ℃ is A→R→M/M→R→A (A—Parent phase B2, CsCl; M—Martensite B19′, monoclinic; R—R phase, rhombohedral), the transformation type of the alloy aged at 400 ℃ changes from A→R→M/M→R→A to A→R→M/M→A; the transformation types of the alloy aged at 500 ℃ and 600 ℃ are A→R→M/M→A and A→M/M→A, respectively. With the increase of aging temperature, the R and M phase transformation temperatures of the alloy increase first and then decrease, and the maximum values 43.7 ℃ and 4.0 ℃ are obtained in the alloys aged at (400 ℃, 50 h) and (500 ℃, 50 h), respectively. The temperature hysteresis of M phase transformation changes in the range of 26.1-122.6 ℃. The temperature hysteresis of the R phase transformation is stable and changes in the range of 4.8-7.5 ℃. With the increase of aging time, the R and M phase transformation temperatures of the alloy increase first and then tend to be stable, the temperature hysteresis of the M phase transformation decreases first and then tends to be stable, and the change of the temperature hysteresis of the R phase transformation is small. The effects of aging temperature on the precipitate morphology and phase transformation behaviors of Ti-50.8Ni-0.1Zr alloy are greater than that of the aging time.
Key words: Ti-50.8Ni-0.1Zr alloy; shape memory alloy; aging process; microstructure; phase transformation behavior
