Superplastic Properties of γ+α_2 Titanium Aluminide Alloy Ti-43Al-(Nb,Mo,B) in Cast + Post-Solidification Heat Treated Condition

摘要

A novel approach to fabrication of globularized fine-grained structure in γ+α_2 titaniumaluminide alloys has been proposed. The approach included the use of a specially designed alloyTi-43Al-X(Nb,Mo,B) and heat treatment. It was found that the ingot structure of the alloy might bepartially globularized on a scale of bulk material using only globularization anneal excluding any hotworking procedure. The microstructure and tensile mechanical properties of the alloy in the cast +heat treated condition were investigated. The tensile mechanical tests were performed in air in thetemperature range of T=900-1130°C at an initial strain rate of ε=1.7×10~(-4)s~(-1).High elongation(δ=160-230%) and low flow stresses (σ=36-100 MPa) typical of superplastic behavior were measuredat T=1050-1 130°C. It was demonstrated that the sheet material produced by spark cutting of the cast +heat treated alloy might be successfully hot formed.