Microstructure and materials characterisation of the novel Al–Cu–Y alloy

The microstructure, hot cracking susceptibility, and mechanical properties of a novel Al–Cu–Y alloy were investigated. The Al–4.7Cu–1.6Y alloy demonstrated very good casting properties, hot cracking susceptibility that is similar to Al–Si–Mg alloys. Analysis of the solidification process showed that the primary Al solidification is followed by the eutectic reaction Liquid→τ1(Al8Cu4Y)+Al and the peritectic reactions Liquid+τ6(Al,Cu)11Y3)→Al+τ1(Al8Cu4Y) (612°C) and Liquid+η(AlCu)→τ1(Al8Cu4Y)+θ(Al2Cu) (595°C). The τ1(Al8Cu4Y) eutectic phase demonstrated high thermal stability during homogenisation treatment. The recrystallisation temperature was in the range 250–350°C after rolling with previous quenching at 540 and 590°C and without heat treatment. The recommended annealing mode for material in the as-rolled condition is 100°C for 1 h: YS = 273 MPa, UTS = 305 MPa and El. = 6.6%.