A brief introduction of dissimilar welding techniquesfor Ti alloy to NiTi alloy

TiNi alloy has shape memory and pseudo-elastic properties, excellent corrosion resistance and good biocompatibility, it provides promising solutions to solve the problems in various applications such as aerospace, atomic energy, microelectronics, and medical equipment [1-2]. Ti alloy has excellent comprehensive properties, such as high specific strength, high specific modulus, hardness, corrosion resistance and high damage resistance [2,3]. Therefore, it will be widely used in aerospace, instrumentation, electronics, chemical industry and other fields. Compared with single material property, this material can use the performance and cost advantages of each material to select the best material for each structural component [4]. However, the weldability of dissimilar materials also limits the wide application of these alloys. This leads to the formation of brittle-like intermetallic compounds (IMCs) in the weld zone. For example, Ti2Ni, NiTi, Ni3Ti [5]. The formation of Ti-Ni IMCs in the weld makes the weld brittle, and the mismatch of the thermal expansion coefficient of the two materials, it will lead to the formation of transverse cracks in the weld and the deterioration of mechanical properties [6-8].