Silicide formation in Ti-3Al-8V-6Cr-4Zr-4Mo

Abstract

TEM, including convergent beam electron diffraction (CBED), SEM, and EDX techniques, were used to] characterize the silicide (Ti, Zr)₅ Si₃ which forms in Beta-C (Ti-3Al-8V-6Cr-4Zr-4Mo) and other similar titanium alloys. Space group of this silicide is determined as P6/mmm. In addition, solvus of this silicide was determined and a complete phase field diagram was constructed for Beta-C alloy. It was found that morphology and distribution of the silicide strongly depends on thermal and thermomechanical treatments. Continuous grain boundary silicide was found to be detrimental for tensil ductility which results in intergranular fracture. Thermal and thermomechanical treatments were identified which can reduce or eliminate continuous grain boundary silicide precipitation.