China Foundry (Nov 2010)
Effect of V and Nb additions on microstructure, properties, and deformability of Ti-45Al-9 (V, Nb, Y) alloy
Abstract
Ti-45Al-9(V, Nb, Y) alloys with four different x=V/Nb (atomic ratio x = 1, 1.5, 2 and 3.5) have been prepared, and the microstructures, properties and hot deformation behaviors were investigated. SEM, XRD and TEM results showed that Ti-45Al-9(V, Nb, Y) alloys were mainly composed of γ, α2, and β phase, and the volume fraction of β phase increased with the increase of the atomic ratio of V/Nb. The alloys were featured with lamellar microstructure with β and γ phases locating at the colony boundaries, and some β precipitates appearing at γ/γ interfaces. It was found that the colony size decreased with the increase of x. The alloys exhibited moderate mechanical properties at room temperature, with a yield strength of over 600 MPa, and fractures showed mainly translamellar character. The alloy with x=3.5 exhibited the best deformability at elevated temperature and that with x=1 had superior oxidation resistance at 800 ℃.
