Niobium - Nickel - Titanium

K.C. Hari Kumar and K. Santhy

Introduction

The knowledge of phase equilibria in Nb-Ni-Ti system is crucial due to its utility in the development and understanding of several technologically important alloys, such as Ti and Nb containing Ni-base superalloys, Nb containing shape memory alloys based on TiNi, etc. Niobium rich ternary alloys of this system can act as hydrogen permeation membrane for separation and purification of hydrogen [2006Luo, 2008Kis]. Alloying NiTi with Nb is known to improve its ductility and expands thermal hysteresis [2004He1, 2004He2, 2006He1, 2006He2], which in turn enables the material to be deformed at low temperatures and yet be safely transported at ambient temperatures [1994Cai]. Literature concerning phase relations, crystal structure and thermodynamics is summarized in Table 1. This system was critically reviewed by [1991Gup, 2008Gup...