Crystallographic Features of α"-Martensite in Titanium Alloys

Institute for Metal Physics, 36 Vernadsky str., 252142 Kiev, Ukraine

Abstract

Equilibrium volume fractions of twins (α₀) and habit plane orientation (n₀) of the orthorhombic α"-martensite in titanium alloys with β-stabilizing elements were determined by minimization of the elastic strain energy. Calculations were made in the basis of one of the twinned domains. It was shown that these parameters are varying considerably depending on the solute element content. For Ti-Ta and Ti-Mo systems habit plane rotated from {434}_β to {433} _β pole and α₀ grew with Ta (Mo) content increase. For Ti-20at%Ta α₀ reached the value of 1, i.e. martensite plate became monodomain. For Ti-Mo system monodomain state was not achieved. For Ti-Nb system converse concentrational dependence of martensite parameters was obtained: α₀ decreased with Nb content increase, and n showed a rotation from {434} _β pole in a direction opposite to that for Ti-Ta and Ti-Mo systems.