The effect of aluminum additions on the thermal, microstructural, and mechanical behavior of NiTiHf shape memory alloys
The effect of aluminum additions on the thermal, microstructural, and mechanical behavior of NiTiHf shape memory alloys
复制标题
DOI：
10.1016/j.jallcom.2015.01.071
复制
发表时间：
2015-07
影响因子：
6.2
通讯作者：
Derek Hsen Dai Hsu;B. Hornbuckle;Billy Valderrama;F. Barrie;H. Henderson;Gregory B. Thompson;Michele V. Ma
中科院分区：
文献类型：
--
作者：
Derek Hsen Dai Hsu;B. Hornbuckle;Billy Valderrama;F. Barrie;H. Henderson;Gregory B. Thompson;Michele V. Ma
Ni50Ti30−XHf20AlX（X= 0，1，2，3，4，5 at.%）合金进行了研究，使用热，微观结构和机械分析。结果表明，Al的加入降低了四元合金的相变温度和热循环稳定性。此外，根据文献中在类似时效温度下进行的先前研究，在时效的3- 5%Al合金中观察到透镜状Han相。虽然在DSC循环降低到−60 °C后，4%和5%的老化铝合金没有检测到相变，但机械测试证实了伪弹性。此外，TEM和原子探针分析证实，在600 °C下老化导致Ni 2 TiAl Heusler相的沉淀，并确定基体中的Al溶解度极限接近3原子%。最后，当比较固溶处理和时效4%和5%Al合金时，观察到由Heusler相引起的沉淀强化。利用XRD、SEM和压缩试验进一步表征微观结构演变。
Ni50Ti30−XHf20AlX(X= 0, 1, 2, 3, 4, 5 at.%) alloys were investigated using thermal, microstructural, and mechanical analysis. It was found that Al additions to this system decreased the transformation temperatures and thermal cyclic stability of the quaternary alloys. Also, the lenticular Han phase was observed in the aged 3–5% Al alloys in accordance with previous studies in literature performed at a similar aging temperature. Though no transformation was detected after DSC cycling down to −60 °C for the aged 4% and 5% Al alloys, mechanical testing confirmed pseudoelasticity. Additionally, TEM and atom probe analysis confirmed that aging at 600 °C resulted in precipitation of the Ni2TiAl Heusler phase and determined the Al solubility limit in the matrix as near 3 at.%. Lastly, precipitation strengthening by the Heusler phase was observed when comparing the solution-treated and aged 4% and 5% Al alloys. Microstructural evolution was further characterized using XRD, SEM and compression testing.