Elastic constants of β-Ti15Mo

Abstract

Elastic constants of single crystals of metastable β-titanium Ti15Mo alloy (in wt. %), grown in an optical floating zone furnace, were measured by resonant ultrasound spectroscopy with the aim to study the dependence of these constants on formation of isothermal ω particles. Samples with different heat treatment (isothermal/anisothermal ageing at different temperatures) were studied. Ultrasonic measurements were complemented by characterization of the samples by transmission electron microscopy. The results proved that isothermal ω particles always exactly follow the original cubic symmetry of the β matrix and that the evolution of the elastic constants of the β-ω multi-phase crystals and the volume fraction of ω phase can be reliably approximated using Hill's homogenizing procedure, assuming cubic elastic constants of the β phase and isotropic elastic constants representing ω particles. It was shown that ultrasonic methods can be used for the study of the evolution of microstructure of metastable β-titanium alloys due to the high contrast in elastic moduli of the β and ω phases.