Strengthening mechanism of two-phase titanium alloys with basketweave microstructure

Abstract

The Ti–Zr–Al–V (TZAV) series alloys having good mechanical properties are potential structural material to apply in the aerospace industry. The strengthening mechanism of those two-ductile phase TZAV alloys with basketweave (BW) microstructure is crucial to their applications in aerospace industry. As a representative of the TZAV series alloys, Ti–30Zr–5Al–3V (TZAV-30) alloy is used for the strengthening mechanism research of TZAV series alloys with BW microstructure. Various heat treatments were designed to obtain different microstructure and tensile properties. XRD patterns show that all heat treated TZAV-30 specimens are wholly composed by two ductile phases, namely, α phase and β phase, no other phase, such as intermetallic compound, is detected. SEM images show that microstructures of all heat treated TZAV-30 specimens are typical BW microstructures. Results show that strength of the TZAV-30 alloy with BW microstructure is greatly dependent on the thickness of the plate α phase and volume fraction of the retained β phase, but nearly independent on the original β phase grain size. A new strategy to determine the microstructure-strength relationship by focusing on the strength of typical two-ductile-phase alloys with BW microstructures is developed. This relationship can be used to analyze the major influencing factors of strength and to forecast the trend of strength in alloys with various BW microstructures.