Microstructure and tensile properties of orthorhombic Ti-Al-Nb-Ta alloys

Microstructure and tensile properties of orthorhombic Ti-Al-Nb-Ta alloys ha ve been studied. In order to optimize ductility and strength of the orthorh ombic alloys with the nominal compositions of Ti-22Al-23Nb-3Ta and Ti-22Al- 20Nb-7Ta, various thermo-mechanical processing steps were implemented as pa rt of the processing route. With a special heat treatment before rolling to obtain a fine and homogeneous rolled microstructure, the rolled microstruc ture resulted in a good combination of high tensile yield strength and good ductility of the alloys through available solution and age treatments. The duplex microstructure with equiaxed alpha(2)/O particles and fine O phase laths in a B2 matrix, deforming in alpha(2) + B2 + O phase field and treati ng in O + B2 phase field, possesses the highest tensile properties. The R.T . yield strength and ductility of the Ti-22Al-20Nb-7Ta alloy are 1200 MPa, and 9.8% respectively. The yield strength and ductility values of 970 MPa a nd 14% were also maintained at elevated temperature (650 degrees C). (C) 20 00 Elsevier Science Ltd. All rights reserved.