Design and preparation of Ti-6Al-1.7Fe-0.1Si-7.3Cr alloy with excellent tensile properties

Abstract

A novel Ti-6Al-1.7Fe-0.1Si-7.3Cr alloy was designed using high-throughput diffusion couple technique. The heat treatment effects on the microstructure and tensile properties of the designed alloy was investigated. The results indicated that the alloys after solution treatment at 800 °C/840 °C and aging at 400 °C/470 °C exhibited high strength (>1200 MPa) and good ductility (>5 %) due to the synergy of spherical α_p phase, coarse flake α_p phase and acicular α_s phase in the β matrix. The precipitation of TiCr₂ Laves phase at aging temperatures above 540 °C led to a decline in ductility. The absence of the spherical α_p phase for the alloy after solution treatmen at 920 °C also resulted in the deterioration of aging elongation. Good balances of strength and ductility were achieved for the alloys after solution treatment at 840 °C and aging at 400 °C/470 °C, with the ultimate tensile strength and tensile elongation of 1237 MPa/23.3 % and 1753 MPa/5.1 %, respectively. Furthermore, the deformation mechanism of the alloys was analyzed, and dislocation slip in α_p phase and β grain was demonstrated to be the main plastic deformation mode.