High temperature shape memory alloys (HTSMAs) manufacturing requires a complex processing procedure. This work presents the application of microwelding as a simple, but a novel method to process NiTiPtIr HTSMAs. Laser microwelding was applied to fuse a NiTi tube cored with a PtIr wire to fabricate a NiTiPtIr alloy wire. X-ray microtomography was used to develop the process and confirm the formation of a uniform NiTiPt phase in the wire volume. After heat treatment, the processed NiTiPt material showed considerable superelasticity at 250 °C with just 0.7% residual strain for a maximum imposed strain of 4%. TEM observations revealed the presence of B19 and a smaller fraction of B19’ martensitic structures in the matrix due to minor changes in the Pt concentration. This laser microwelding enabled selective alloying for the fabrication of NiTiPtIr which opens the door toward a more straightforward production method for ternary NiTi-based HTSMAs.

中文翻译：

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激光微焊接作为一种新型合金化工艺来制造 NiTiPtIr 高温形状记忆合金

高温形状记忆合金（HTSMA）的制造需要复杂的加工过程。这项工作提出了微焊接的应用，作为一种简单但新颖的方法来加工 NiTiPtIr HTSMA。采用激光微焊接熔合以 PtIr 线为芯的 NiTi 管，制造 NiTiPtIr 合金线。X 射线显微断层扫描用于开发该工艺并确认在线体积中形成均匀的 NiTiPt 相。热处理后，加工后的 NiTiPt 材料在 250 °C 时表现出相当大的超弹性，最大施加应变为 4%，残余应变仅为 0.7%。TEM 观察表明，由于 Pt 浓度的微小变化，基体中存在 B19 和一小部分 B19' 马氏体结构。这种激光微焊接实现了 NiTiPtIr 制造的选择性合金化，这为三元 NiTi 基 HTSMA 的更直接的生产方法打开了大门。