Identification of the L6o Phase in A γ-1bTi-1bAl-1bNb Alloy

Studies to identify the phases present in various alloys of the Ti-AI-Nb ternary system are currently being pursued in order to determine the details of processing routes for generating desired microstructures (1,2). For the region of the ternary from about 50a/oAI to about 20a/oAI and Nb up to 35a/o, a number of phases are present, including β, B2, α, α2, and γ(2). When the Nb content is high and the concentration of AI is between 40 and 50a/o, the phases present at room temperature are expected to be γ and either B2 or δNb2AI phases. At high temperature (\u3e1000°C), however, the phase boundaries in this region are not well known. This report presents results on the identification of a high temperature phase not reported before for the Ti-AI-Nb system. The alloy studied contains 36.8Ti-42.9AI-20.3Nb (a/o), as determined by microprobe analysis