Precipitation Behavior of Cu-1.9Be-0.3Ni-0.15Co Alloy During Aging

In this paper, the evolutions of microstructure and mechanical properties of Cu-1.9Be-0.3Ni-0.15Co alloy were studied. The alloys in the condition of the solution treated (soft state) and 37% cold rolled (hard state) were aged at 320 °C for different time, respectively. The mechanical properties, electrical conductivity and microstructure of the alloy aged for different time were analyzed. Additionally, the precipitation kinetics of Cu-1.9Be-0.3Ni-0.15Co alloys was investigated. X-ray diffraction and transmission electron microscopy results reveal that both continuous precipitation and discontinuous precipitation existed in the hard-state Cu-1.9Be-0.3Ni-0.15Co alloy during the whole aging process; the sequence of continuous precipitation is G.P. zone → γ″ → γ′ → γ. Furthermore, the precipitation transformation mechanism of soft-state alloy is homogeneous nucleation, while hard-state alloy shows the heterogeneous nucleation (interface nucleation) with the nucleation rate of both states decaying rapidly to zero during aging at 320 °C.