The Effect of β Stabilizers on the Structure and Energy of α/β Interfaces in Titanium Alloys

Abstract

The structure and energy associated with interfaces between the BCC and HCP lattices (β and α phase, respectively) in titanium alloys with commonly used β stabilizers were analyzed. For this purpose, the crystallographic structure of the matching facets of broad, side and end faces was described using misfit dislocations and structural ledges which compensate the mismatch in atomic spacing of the α and β phases. The effect of the β/α transformation temperature due to various concentration of β stabilizers on periodicity of misfit dislocations and structural ledges was estimated. The van der Merwe approach was used to calculate energy of different matching facets. An increase in the percentage of β-stabilizing elements was found to result in a decrease in the lattice-parameter ratio (aβ/aα) and an increase in the energy of all faces. The dependence of the interface energy on the aβ/aα ratio was for the first time quantified, and insight into the preferred shape of α-phase precipitates was obtained.