On the texture of spray formed gamma titanium aluminide

Abstract

Spray forming is an attractive processing route for titanium aluminides that combines advantages both of ingot and powder metallurgy. Spray formed deposits were produced using the electrode induction melting gas atomization technique. The texture of a spray formed Ti–48.9 at.% Al deposit in the as-sprayed state and after isothermal forging as well as after isothermal forging and a subsequent stress relief heat treatment was analysed by means of neutron diffraction. The spray formed deposit was found to have a very weak left angle bracket1 1 1right-pointing angle bracket-fibre texture with a maximum pole density of 1.12 multiples of random distribution. After isothermal forging of cylinders to 77% reduction at an initial strain rate of 2 × 10−3 s−1 at 1150 °C, a band of orientations from left angle bracket1 0 1right-pointing angle bracket to left angle bracket1 0 0right-pointing angle bracket with a maximum close to left angle bracket3 0 2right-pointing angle bracket was found. A Zener–Hollomon parameter of 12.6 is estimated, which indicates that during isothermal forging dynamic recrystallization is governed by nucleation of new grains. A subsequent stress relief treatment at 1030 °C for 2 h caused additional grain growth, after which the maximum pole density is increased from 3.3 to 3.8 times random.