Effect of ternary alloying elements on microstructure and superelastictity of Ti-Nb alloys

The effect of ternary alloying elements (X=Ta, Fe, Zr, Mo, Sn and Si) on the microstructure, the mechanical properties and the superelasticity of Ti--22Nb-X alloys were investigated. The 1% addition of a ternary alloying element (X = Ta, Fe, Zr, Mo, Sn and Si) has a slight influence on the microstructure of the Ti-22Nb alloy. All the alloys after solution-treatment at 1073 K for 1.8 ks contain beta and alpha '' phases. The elements of Sn, Si, Fe and Ta with a high number of valence electrons or a small atomic size have a strong solid-solution strengthening effect to the beta phases in the alloys and the alloys with high (Md) over bar and low (Bo) over bar exhibit low elastic moduli. All the alloying elements improve the superelasticity of Ti-22Nb-X alloys. The elements, Fe, Mo, Sn and Si, which are with a high number of valence electrons and a small atomic size, strongly increase sigma(SIM) of the Ti-22Nb alloy. (C) 2012 Elsevier B.V. All rights reserved.