Question

The Al-Cu equilibrium phase diagram is reported below. For age hardening the alloy containing 4% of Cu: 700 (660 L 600 a+ @+L O 5.65 $25 500 Temperature (°C) 400 + 300 200 AI 10 20 30 40 SO Weight percent copper Select one: O a. a microstructure consisting of alpha phase with theta phase precipitated at grain boundaries must be obtained b. initially the alloy must be first solution annealed at 550 °C and then quenched down to room temperature O c. alpha phase is quenched from 550 °C down to room temperature to obtain a martensitic microstructure d. the alloy must be first solution annealed at 550 °C and then cooled down to room temperature at low cooling rate O e. the alloy must be first aged at the chosen temperature and then solution annealed

Answer 1

Option d is the answer

The alloy must be first solution annealed to 550 degree centigrade and then cooled down to room temperature at low cooling rate.