Microstructure evolution and quench sensitivity of Cu-10Ni-3Al-0.8Si alloy during isothermal treatment

The variation of properties and evolution of microstructure of Cu-10Ni-3Al-0.8Si alloy during isothermal and aging treatment was studied. The time-temperature-property curves of the alloy were established. The nose temperature of the alloy was about 662 degrees C, and the alloy presented high quench sensitivity when quenched in the nose temperature zone. Discontinuous precipitation occurred when Cu-10Ni-3Al-0.8Si alloy was isothermally treated at 550 degrees C, and the discontinuous precipitates at the grain boundary became coarse when the isothermal temperature increased to 650 degrees C. Further increasing the isothermal temperature to 750 degrees C, cellular precipitation occurred in the alloy. Both Ni3Al precipitates with L1(2) ordered structure and d-Ni2Si precipitates with DO22 ordered structure precipitated in the isothermally treated Cu-10Ni-3Al-0.8Si alloy. The orientation relationships between the precipitates and matrix were determined as [001]Cu parallel to[001](Ni3Al)parallel to[001](delta), (110)(Cu)parallel to(110)(Ni3Al)parallel to(010)(delta), and (1 (1) over bar0)(Cu)parallel to(1 (1) over bar0)(Ni3Al) parallel to(100)(delta).