Effect of Interlayer on Microstructure and Mechanical Properties for NiTi/Ti6Al4V Laser Welded Joints
CUI Jiangmei1, CHEN Long2, ZHOU Zhijie3, TESHOME Fissha Biruke2, KE Wenchao2, YU Hongmei1, ZENG Zhi2
1. Chengdu Technological University, Chengdu 611730, China;
2. University of Electronic Science and Technology of China, Chengdu 611731, China;
3. AVIC International Holding Corporation, Beijing 100101, China
In order to reduce the formation of brittle intermetallic compounds in NiTi/Ti6Al4V dissimilar laser welding and improve the mechanical properties of welded joints, NiTi/Ti6Al4V laser welding was performed by adding Co and Zr interlayers respectively. The effect of Co/Zr interlayer on microstructure, phase structure and mechanical properties of welded joints was studied. The results show that the microstructure of the fusion zone in NiTi/Co/Ti6Al4V and NiTi/Zr/Ti6Al4V joints is composed of equiaxed dendrites, columnar dendrites and some macroscopic segregation zones. Co and Zr can respectively replace Ni and Ti in Ti2Ni brittle intermetallic compounds, which inhibits the formation of brittle phases. In addition, the maximum hardness of NiTi/Co/Ti6Al4V and NiTi/Zr/Ti6Al4V joints is near the NiTi boundary, 543HV and 467HV respectively. Meanwhile, brittle fracture occurs at the NiTi boundary. The NiTi/Zr/Ti6Al4V joint has a large tensile
strength of 315.9 MPa and fracture strain of 1.74%.
2022, 
