Abstract The Cu-13.5Al-4Ni-0.5Ti copper-based shape memory alloys (SMAs) were fabricated by selective laser melting (SLM). The parameters were optimized to obtain almost fully dense copper-based SMAs samples. The phases and microstructures were characterized and the tensile properties at room temperature and 200 °C were evaluated. The XRD results showed that only the β1′ phase could be detected in the Cu-based SMAs, which was attributed to the extremely short solidification time for the precipitation of α and γ2 phases during SLM process. The grains were well refined and the average grain size was approximate 43 μm, which was much smaller than that of the cast copper-based SMAs. The X-phase (Cu2TiAl) is observed, which is granular and size 20–50 nm. The Cu-13.5Al-4Ni-0.5Ti copper-based SMAs fabricated by SLM exhibited excellent mechanical properties at room temperature, which was higher than that of the cast copper-based SMAs. This is attributed to two aspects: (1) grain refinement, (2) suppress of brittle γ2 phase. Remarkably, the tensile test results at 200 °C showed both higher strength and elongation, which is attributed to the bcc structure of the parent phase and the stress-induced martensitic transformation at 200 °C. Meanwhile, the difference of microstructures and properties between SLM-fabricated Cu-based SMAs and casting Cu-based SMAs were analyzed and discussed in detail.

中文翻译：

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选择性激光熔化制备Cu基形状记忆合金的工艺优化、微观结构和力学性能

摘要 采用选择性激光熔化（SLM）方法制备了Cu-13.5Al-4Ni-0.5Ti铜基形状记忆合金（SMA）。优化参数以获得几乎完全致密的铜基 SMA 样品。表征了相和微观结构，并评估了室温和 200 °C 下的拉伸性能。XRD结果表明，在Cu基SMA中只能检测到β1'相，这归因于SLM过程中α和γ2相析出的凝固时间极短。晶粒细化良好，平均晶粒尺寸约为 43 μm，远小于铸造铜基 SMA。观察到 X 相 (Cu2TiAl)，它是颗粒状的，尺寸为 20-50 nm。Cu-13.5Al-4Ni-0。SLM制备的5Ti铜基SMA在室温下表现出优异的机械性能，高于铸造铜基SMA。这归因于两个方面：（1）晶粒细化，（2）脆性γ2相的抑制。值得注意的是，200 °C 下的拉伸试验结果显示出更高的强度和伸长率，这归因于母相的 bcc 结构和 200 °C 时应力诱导的马氏体转变。同时，详细分析和讨论了SLM制造的Cu基SMA与铸造Cu基SMA在组织和性能上的差异。200 °C 下的拉伸试验结果显示出更高的强度和伸长率，这归因于母相的 bcc 结构和 200 °C 下的应力诱导马氏体转变。同时，详细分析和讨论了SLM制造的Cu基SMA与铸造Cu基SMA在组织和性能上的差异。200 °C 下的拉伸试验结果显示出更高的强度和伸长率，这归因于母相的 bcc 结构和 200 °C 下的应力诱导马氏体转变。同时，详细分析和讨论了SLM制造的Cu基SMA与铸造Cu基SMA在组织和性能上的差异。