Correlation of structure and flow behaviour of Cu–Ti–Cd alloys

The work hardening behaviour of Cu–3Ti–1Cd and Cu–4Ti–1Cd alloys has been studied by conducting tensile tests at room temperature in solution treated, peak aged and overaged conditions. The flow behaviour has been analyzed using various true stress–true strain relationships. The Ludwigson relationship provides the best fit for the true stress–strain data of the two alloys at 298 K in all the conditions studied. The Hollomon equation as well as Ludwik equation fits the experimental σ–ɛ data for both the alloys reasonably well in highly overaged condition. While both the alloys exhibit transient flow behaviour at lower strains in solution treated condition, Cu–3Ti–1Cd alloy only exhibits this behaviour in peak aged condition. No such transition was observed in overaged condition of both the alloys. Further, these alloys display higher flow stress and strain hardening rates in peak aged condition than that in solution treated condition. Cu–3Ti–1Cd alloy shows higher flow stress and lower strain hardening rates in overaged condition than in the solution treated condition. On the other hand, Cu–4Ti–1Cd alloy exhibits lower flow stress as well as lower strain hardening rates in overaged condition when compared to that in solution treated condition. The observed behaviour in Cu–4Ti–1Cd alloy is related to the modulated structure with fine precipitates of Cu4Ti present in solution treated condition as compared to coarse and diffuse lamellar structure in overaged condition.