Structure-property orientation relationship of a /a2/Ti5Si3 in as-cast Ti-45Al-2Nb-0.7Cr-0.3Si intermetallic alloy

Abstract

Structure-property relationship of the as-cast -Ti-45Al-2Nb-0.7Cr-0.3Si based intermetallic alloy was examined. The phases stable at room temperature in the alloy were /a(sub)2/Ti(sub)5Si(sub)3, 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 (ß-solidifying) and heat-treated (a-solidifying) microstructural phases. The results showed that the formation of /a(sub)2/Ti(sub)5Si(sub)3 follows the Blackburn orientation relationship (BOR): (ß-solidifying) {110}(sup)ß//{0001}(sup)a and <111>(sup)ß//<2 1 10>(sup)a, and for (a-solidifying) = (111) || (0001)a and <1 10] || <11 20>a.