构建方向对激光粉床熔化NiTi记忆合金微观组织和功能特性的影响  

Influence of building direction on microstructure and functional properties of NiTi memory alloys fabricated by laser powder bed fusion

作　　者：王成[1] 李昊航 陈捷 赵昆[1] 崔立山[1] 郝世杰[1] WANG Cheng;LI Haohang;CHEN Jie;ZHAO Kun;CUI Lishan;HAO Shijie(College of New Energy and Materials,China University of Petroleum(Beijing),Beijing 102249;Institute of Machinery Manufacturing Technology,China Academy of Engineering Physics,Mianyang 621900,China)

机构地区：[1]中国石油大学(北京)新能源与材料学院,北京102249 [2]中国工程物理研究院机械制造工艺研究所,四川绵阳621000

出　　处：《功能材料》2024年第11期11017-11023,共7页Journal of Functional Materials

基　　金：国家重点研发项目(2022YFB4600500);国家安全学术基金项目(U2130201、U2330105)。

摘　　要：在激光粉床熔化(LPBF)技术制造三维金属构件过程中,构建方向导致的热历史差异可能会引起晶粒形态、缺陷数量和相组成的变化,从而影响构件的力学性能和功能特性。探讨了0°、45°和90°3种构建方向对NiTi形状记忆合金微观组织和力学性能的影响。采用扫描电子显微镜(SEM)、光学显微镜、X射线衍射(XRD)和差示扫描量热法(DSC)分析了LPBF制备NiTi合金的微观组织和相变行为,并通过变温拉伸测试评估了NiTi合金在马氏体和奥氏体状态下的力学性能和功能特性。结果表明,0°、45°和90°样品的熔池类型分别为传导模式、混合模式和匙孔模式。在室温和100℃下,0°、45°和90°样品的拉伸应变分别为10.5%/8.5%、17%/11%和9.5%/5.5%。在室温下拉伸6%后,3组样品的可恢复应变分别为3.3%、3.4%和3.8%。In the laser powder bed fusion(LPBF)manufacturing,the thermal history differences caused by the building direction may lead to variations in grain morphology,defect quantity,and phase composition of metallic components,thereby impacting the mechanical and functional performances of the components.This study was designed to investigate the effects of three building directions,0°,45°,and 90°,on the microstructure and mechanical properties of LPBF-fabricated NiTi shape memory alloys.The microstructure and transformation behaviors were analyzed using scanning electron microscopy(SEM),optical microscopy,X-ray diffraction(XRD),and differential scanning calorimetry(DSC).The mechanical and functional performances of NiTi alloys in both martensitic and austenitic states were evaluated through temperature-controlled tensile testing.The results indicate that the melt pool types for the 0°,45°,and 90°samples are conduction mode,mixed mode,and keyhole mode,respectively.At room temperature and 100℃,the tensile strains of the 0°,45°,and 90°samples are 10.5%/8.5%,17%/11%,and 9.5%/5.5%,respectively.After tensile pre-deformed to 6%at room temperature,the shape memory strains of the three groups of samples are 3.3%,3.4%,and 3.8%,respectively.

关 键 词：NITI形状记忆合金 激光粉床熔化 构建方向 相变行为 拉伸性能 

分 类 号：TG139.6[一般工业技术—材料科学与工程] TG665[金属学及工艺—合金]