A method to determine main microstructural features influencing mechanical properties of two-phase titanium alloys

Abstract

A new method to determine the major–minor sequence of microstructural features influencing mechanical properties of two-phase titanium alloys was proposed in a ternary microstructural system composed of equiaxed α phase, coarse α plates and residual β matrix in this investigation. The triplex heat treatment in (α+β) two-phase field was carried out on two-phase titanium alloys to change the relative contents of three microstructural features. The microstructure–property relationships described in the form of three-dimensional curved surface were established by interpolating property data and corresponding content data of these microstructural features in a stereoscopic triangular coordinate system. The major–minor sequence of microstructural features was determined by comparing the angles between contour lines of property surfaces and coordinate axes. The main microstructural feature influencing alloy׳s properties in a binary microstructual system was determined by superimposing the vertical section of a three-dimensional property surface along one coordinate axis and its corresponding major–minor sequence distribution. Validated using Ti–6Al–2Sn–2Zr–3Mo–1Cr–2Nb–Si alloy, the method is generally applicable to all two-phase titanium alloys or other alloys having a ternary microstructural system.