激光扫描速度对4D打印钛镍形状记忆合金相转变和超弹性的影响

Influence of Laser Scanning Speed on Phase Transformation and Superelasticity of 4D-printed Ti-Ni Shape Memory Alloys

通过调控激光扫描速度,运用4D打印技术制备出具有不同相转变温度和微观结构的钛镍形状记忆合金。结合XRD、DSC、SEM和循环压缩等分析方法研究了不同扫描速度对4D打印钛镍合金相组成、相转变、微观结构和超弹性的影响。结果表明,当激光扫描速度从80 mm/s到150 mm/s时,4D打印钛镍合金中马氏体相(B19’)含量减少,奥氏体相(B2)含量增加;马氏体转变开始温度(Ms)和奥氏体转变结束温度(Af)随激光扫描速度增加而降低。奥氏体状态下循环压缩试验结果表明:激光扫描速度为80mm/s时,4D打印钛镍合金具有良好的超弹性,10次循环压缩后稳定的可回复应变达到4.99%,高于目前文献报道的回复应变2.64%;激光扫描速度为150 mm/s时,在3次循环压缩后回复应变几乎保持在4.55%不变。

By adjusting laser scanning speed during 4 D printing, Ti-Ni shape memory alloys(SMAs) with different phase transformation temperatures and microstructures are manufactured. The influences of laser scanning speed on phase component, phase transformation temperature, microstructure and superelasticity of 4 D-printed Ti-Ni SMAs are analyzed by various methods of XRD, DSC, SEM and cyclic compression experiment. The results show that the volume fraction of martensite(B19’) in 4 D-printed TiNi SMAs decreases together with the gradually increased volume fraction of austenite(B2) when the laser scanning speed increases from 80 mm/s to 150 mm/s. Meanwhile, the martensite transformation start temperature(Ms) and the austenite transformation finish temperature(Af) decrease with the increase of laser scanning speed. At the laser scanning speed of 80 mm/s, the cyclic compression experiments under austenite state(B2) show that the 4 D-printed Ti-Ni SMAs have good superelasticity, exhibiting the stable recovery strain of 4.99% after ten times cyclic compression. It’s much higher than the recovery strain of 2.64%, which have been reported. With the increased laser scanning speed to 150 mm/s, the recovery strain remains at 4.55% after three cycle compressions.