High temperature tensile behaviour of a Cu–1.5 wt.% Ti alloy

Abstract

The high temperature tensile properties of a Cu–1.5 wt.% Ti alloy have been investigated in the temperature range of 100–550 °C. Substantial increase in yield and tensile strengths of solution treated alloy is observed with increasing temperature, with a peak at 450 °C and decrease in strength beyond this temperature. In situ age hardening during testing at elevated temperatures resulting in the precipitation of ordered, metastable and coherent Cu 4Ti (β 1) phase is attributed to the increase in strength up to 450 °C and coarsening of β 1 precipitate particles decreases the strength at temperatures greater than 450 °C. In the peak-aged condition, however, the yield and tensile strengths are nearly constant up to 350 °C and decrease thereafter, up to 550 °C. The decrease in strength beyond 350 °C in the peak aged Cu–1.5Ti alloy is attributed to the coarsening of precipitate particles and thermally activated cross-slip occurring at high temperatures, which makes the movement of the dislocations easy. The high temperature tensile properties of Cu–1.5Ti alloy are comparable at 300 °C and even better at 425 °C than those of Cu–1.5Ti–2.5Sn, Cu–1.5Ti–2.5Sn–0.5Cr and Cu–0.65Be–2.7Co alloys. Ductile mode of fracture is observed even at elevated temperatures.