The excellent mechanical properties of NiTi alloys, such as unique shape
memory effect, superelasticity, as well as good biocompatibility, excellent corrosion
resistance, low elastic modulus and good ductility, make it an ideal choice for the
biomedical, aerospace and intelligent materials. However, NiTi alloy with itself and
dissimilar material connection problems NiTi alloy can only have a simple geometry,
thus limiting the NiTi alloy more widely used. For this reason, resistance welding and
laser welding are proposed by scholars, but these methods are not widely used due to
the fact that welding makes the joint parts easy to produce brittle second phase and
large area heat-affected zone, which also needs a large amount of solder. In this
chapter, NiTi / NiTi-Nb alloy was fabricated by heating niobium and NiTi wires in a
high-temperature argon atmosphere furnace to 1185 °C for 6min. The results show that
there are 4 diffusion layers, including Nb foil, NiTi-Nb eutectic region, pre-eutectic
NiTi region and NiTi matrix at the junction of NiTi wire and Nb foil. In addition,
martensite phase was found inside the NiTi matrix. In the NiTi-Nb eutectic diffusion
layer, niobium is inhomogeneously distributed, forming a rod-like Nb-rich phase,
facetted Ti-rich phase and stripe-like or equiaxed NiTi-Nb eutectic structure. The
experimental study on the microstructure and mechanical properties of interface
interface between NiTi and Nb will help to understand the advantages of using Nb as
the NiTi alloy connection material, provide theoretical support for preparation of NiTi
lattice materials, and promote NiTi alloy more extensive application.
Keywords: Diffusion layers, Mechanical property, Microstructure, NiTi/NiTi-Nb
alloys.
