热处理对重复扫描的选择性激光熔化镍钛形状记忆合金的影响。

Effect of Heat Treatment on Repetitively Scanned SLM NiTi Shape Memory Alloy.

作者信息

Khoo Zhong Xun, An Jia, Chua Chee Kai, Shen Yu Fang, Kuo Che Nan, Liu Yong

机构信息

Institute for Sports Research, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore.

Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore.

出版信息

Materials (Basel). 2018 Dec 26;12(1):77. doi: 10.3390/ma12010077.

DOI:10.3390/ma12010077

PMID:30587793

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC6337191/

Abstract

Selective Laser Melting (SLM) has been implemented to address the difficulties in manufacturing complex nickel titanium (NiTi) structures. However, the SLM production of NiTi is much more challenging than the fabrication of conventional metals. Other than the need to have a high density that leads to excellent mechanical properties, strict chemical compositional control is required as well for the SLM NiTi parts to exhibit desirable phase transformation characteristics. In addition, acquiring a high transformation strain from the produced specimens is another challenging task. In the prior research, a new approach-repetitive scanning-was implemented to achieve these objectives. The repetitively scanned samples demonstrated an average of 4.61% transformation strain when subjected to the tensile test. Nevertheless, there is still room for improvement as the conventionally-produced NiTi can exhibit a transformation strain of about 6%. Hence, post-process heat treatment was introduced to improve the shape memory properties of the samples. The results showed an improvement when the samples were heat treated at a temperature of 400 °C for a period of 5 min. The enhancement in the shape memory behavior of the repetitively scanned samples was mainly attributed to the formation of fine Ni₄Ti₃ metastable precipitates.

摘要

选择性激光熔化（SLM）技术已被用于解决制造复杂镍钛（NiTi）结构时遇到的困难。然而，SLM工艺生产NiTi比制造传统金属更具挑战性。除了需要具有高密度以获得优异的机械性能外，对于SLM NiTi零件展现出理想的相变特性而言，还需要严格控制化学成分。此外，从生产的试样中获得高转变应变是另一项具有挑战性的任务。在先前的研究中，采用了一种新方法——重复扫描来实现这些目标。经重复扫描的样品在进行拉伸试验时，平均转变应变为4.61%。然而，仍有改进空间，因为传统生产的NiTi可展现约6%的转变应变。因此，引入了后处理热处理来改善样品的形状记忆性能。结果表明，当样品在400℃温度下热处理5分钟时，性能得到了改善。重复扫描样品形状记忆行为的增强主要归因于细小的Ni₄Ti₃亚稳析出相的形成。