Ni含量对激光粉末床熔融成形NiTi形状记忆合金显微组织和力学性能的影响  

Effects of Ni Concentration on Microstructures and Mechanical Properties of NiTi Alloys Fabricated via Laser Powder Bed Fusion

作　　者：康景涛 刘子豪 郑聃 李瑞迪[1] 赖端 刘鑫炎 黄文静 梁恩泉[3] KANG Jingtao;LIU Zihao;ZHENG Dan;LI Ruidi;LAI Duan;LIU Xinyan;HUANG Wenjing;LIANG Enquan(State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China;Farsoon Technologies Co.,Ltd.,Changsha 410221,China;Shanghai Aircraft Design and Research Institute,Shanghai 201210,China)

机构地区：[1]中南大学粉末冶金国家重点实验室,湖南长沙410083 [2]湖南华曙高科技有限责任公司,湖南长沙410221 [3]上海飞机设计研究院,上海201210

出　　处：《铸造技术》2023年第7期649-656,共8页Foundry Technology

基　　金：湖南省科技创新平台与人才计划(2022RC3033);山东省自然科学基金(ZR2020ZD04);凝固技术国家重点实验室开放课题(SKLSP202109)。

摘　　要：激光粉末床熔融(laser powder bed fusion,LPBF)成形NiTi合金由于Ni元素的蒸发导致成分偏离粉末设计成分,而NiTi合金的形状记忆效应、超弹性等性能受Ni含量影响极大。因此有必要对不同Ni含量NiTi合金的LPBF成形性、显微组织以及力学性能开展研究。采用真空电极感应熔炼气雾化技术制备了Ni_(50.8)Ti、Ni_(51.0)Ti以及Ni_(51.5)Ti(原子分数,%)3种预合金粉末,研究其在不同工艺参数下的冶金缺陷、显微组织及力学性能的演化规律。结果表明,高Ni含量NiTi合金在LPBF成形过程中容易产生垂直于建造方向的裂纹,成形性较低Ni含量NiTi合金差。Ni_(51.5)Ti合金室温下的临界应力可达476 MPa,但断裂伸长率仅为2%;Ni_(50.8)Ti合金临界应力仅为122 MPa,断裂伸长率可达8%。Laser powder bed fusion(LPBF)forming of NiTi alloys deviates from the powder design composition due to the evaporation of Ni,and the properties of NiTi alloys such as the shape memory effect and superelasticity are greatly influenced by the Ni content.Therefore,it is necessary to investigate the LPBF formability,microstructure and mechanical properties of NiTi alloys with different Ni contents.In this paper,Ni_(50.8)Ti,Ni_(51.0)Ti and Ni_(51.5)Ti(atomic percent,%)pre-alloy powders were prepared by the electrode induction melting gas atomization technique,and the evolution of metallurgical defects,microstructure and mechanical properties of the three alloys were studied under different process parameters.The results show that the high Ni content NiTi alloy is prone to cracking perpendicular to the building direction during the LPBF forming process,and the formability is worse than that of the low Ni content NiTi alloy.The critical stress of the Ni_(51.5)Ti alloy can reach 476 MPa at room temperature,but the fracture elongation is only 2%;the critical stress of the Ni_(50.8)Ti alloy is only 122 MPa,and the fracture elongation can reach 8%.

关 键 词：粉末床激光熔融 NITI合金 显微组织 力学性能 成分调控 

分 类 号：TG665[金属学及工艺—金属切削加工及机床]