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Abstract A process of heating-cooling combined mold horizontal continuous casting→cold rolling→solid-solution treatment was used to produce Cu-1.7 wt% Be alloy sheet, and the precipitation behavior, microstructure and properties of the Cu-1.7 wt% Be alloy sheet during aging were investigated. The results showed that the phase transformation sequence of the alloy during aging at 325 °C was GP zone→γ″→γ′→γ equilibrium phase. The reasonable aging parameters were aging temperature of 325 °C and aging time of 3 h, and the hardness, tensile strength and yield strength of the aged alloy reached the peak values of 375 HV, 1042 MPa and 778 MPa, which were 172%, 116%, and 255% higher than those of the solid-solution alloy, respectively, and the electrical conductivity was 22.4% IACS. The formation of a large number of dispersed nano-sized γ′ phase was mainly responsible for the high strength of the alloy. A dynamic model of aging precipitation was established and the yield strength of the peak-aged alloy was calculated by the strengthening model. The deviation of the calculated value (797 MPa) and the measured value (778 MPa) was 2.4%, and the strengthening mechanism of the peak-aged alloy was determined as the Orowan bypass mechanism. Graphical abstract Image 1 Highlights • HCCM horizontal continuous casting→cold rolling→solid-solution treatment→aging was used to produce Cu-1.7 wt% Be alloy sheet • Formation of dispersed nano-sized γ′ phase was mainly responsible for the high strength of the alloy. • Strengthening mechanism of the peak-aged alloy was Orowan bypass mechanism. [ABSTRACT FROM AUTHOR]

The fatigue crack growth (FCG) behaviors of Cu–Be–Co–Ni alloy subjected to interrupted aging (IA), normal aging (NA) and overaging (OA) treatment were discussed. The distinctions in microstructure of the alloys after various aging treatments led to different FCG behaviors. In order to understand the different FCG behaviors, a model based on the reversible plastic zone (RPZ) size and microstructural factors was applied in this study. At the relatively low stress intensity factor range (Δ K < 17 MPa m 1/2 ), the RPZ size of each sample was smaller than the corresponding grain size, so the fatigue crack propagated inside the grain and adjacent to the grain boundaries (GBs). For the IA alloy, fine and coherent γ″ precipitates which could be sheared by dislocations promoted the fatigue crack resistance, leading to the decrease of FCG rate. When the value of stress intensity factor range becomes higher (Δ K > 21 MPa m 1/2 ), the RPZ size of each sample was 1–2 times of the corresponding grain size. Consequently, the crack trended to grow along GBs. For the OA alloy, the crack propagated along the interfaces between the discontinuous precipitation (DP) cells and parent phase. The tortuous interfaces hindered the propagation of the fatigue cracks, resulting in the reduction of FCG rate. [ABSTRACT FROM AUTHOR]