New metallurgical methods for joining nickel titanium.

摘要

Nickel titanium is an intermetallic alloy used in many applications because it demonstrates shape memory and pseudoelasticity at near room temperature. Historically, methods of joining nickel titanium have had limited success.;This thesis reports on a variety of preliminary experiments on creating metallurgical bonds with NiTi that take advantage of a pseudo-binary equilibrium system between NiTi and Nb. This system allows pure Nb to act as a melting point depressant for NiTi. Bonds between NiTi sections have exhibited high strength and ductility. The technique has been used to create low density honeycomb topologies capable of geometrically amplifying pseudoelastic and shape memory effects.;The liquid formed by this pseudo-binary is highly reactive, and aggressively wets many metallic and non-metallic surfaces. DC magnetron sputtered multilayers of NiTi and Nb can be used to control the reactivity of the liquid. These multilayers themselves exhibit shape memory and high transformation temperatures, which demonstrates achievement of good composition control. When combined with niobium cladding, multilayers also allow NiTi to be bonded with many other materials without the formation of undesired intermetallic compounds.