Structure-property orientation relationship of a γ/α2/Ti5Si3 in as-cast Ti-45Al-2Nb-0.7Cr-0.3Si intermetallic alloy

Abstract

Structure-property relationship of the as-cast γ-Ti-45Al-2Nb-0.7Cr-0.3Si based intermetallic alloy was examined. The phases stable at room temperature in the alloy were γ/α2/Ti5Si3, respectively; while their crystal structures were described by means of chemical formulas, Pearson's number, space groups, lattice parameters, atomic positions and occupancy numbers using a Vienna ab initio simulation package (VASP) software for materials design. Moreover, high resolution electron backscatter diffraction (HSEBSD) was used to analyse the orientation relationship of both the as-cast (β-solidifying) and heat-treated (α-solidifying) microstructural phases. The results showed that the formation of γ/α2/Ti5Si3 follows the Blackburn orientation relationship (BOR): (β-solidifying) {110}β//{0001}α and <111>β//<2‾1‾10>α, and for (α-solidifying) = (111)γ || (0001)α and <1‾10]γ || <11‾20>α.