Abstract
Elastic constants of single crystals of metastable beta-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 omega 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 omega particles always exactly follow the original cubic symmetry of the beta matrix and that the evolution of the elastic constants of the beta-omega multi-phase crystals and the volume fraction of omega phase can be reliably approximated using Hill's homogenizing procedure, assuming cubic elastic constants of the beta phase and isotropic elastic constants representing omega particles.
It was shown that ultrasonic methods can be used for the study of the evolution of microstructure of metastable beta-titanium alloys due to the high contrast in elastic moduli of the beta and omega phases. (C) 2019 Published by Elsevier B.V.