Anisothermal Alpha Phase Formation in Ti-6.8Mo-4.5Fe-l.5Al

摘要

This investigation has examined the formation of alpha phase during cooling in Ti-6..8Mo-4.5Fe-1.5Al (TIMET LCB). Cooling rates between 500 and 0.29 Ks~(-1) were examined utilizing a modified end-quench procedure. Following cooling, optical, scanning and transmission electron microscopy together with wide angle and rocking curves x-ray diffraction analysis procedures were used to examine alpha formation. The latter techniques indicate that alpha phase formation commenced at rates ≤ 8 Ks~(-1). Initially heterogeneous nucleation of alpha occurs at prior beta phase grain corners, decreasing cooling rate resulting in additional nucleation and growth of alpha at prior beta grain boundaries, inclusion-matrix interfaces and finally within the prior beta matrix.