Precipitate sequence, strengthening mechanism and properties of Cu-0.9Be-1.0Ni alloys prepared by powder metallurgy

• The Cu-0.9Be-1.0Ni alloy with excellent comprehensive properties was innovatively prepared by powder metallurgy. • The precipitation evolution sequence of the Cu-0.9Be-1.0Ni alloy is GP zone + γ″ + γ′ → γ″ + γ′ → γ′ → γ′+ γ. • The strength calculated via the Orowan strengthening mechanism agrees with experimental measurements. • The comprehensive properties of Cu-0.9Be-1.0Ni alloys produced via hot-pressed sintering surpass those of alloys fabricated by spark plasma sintering. The present investigation provides a comprehensive analysis of sintering, solid-solution treatment, and aging effects on precipitation behavior in powder-metallurgy processed the Cu-0.9Be-1.0Ni alloys. Optimal processing of the powder-metallurgy Cu-0.9Be-1.0Ni alloy occurs at 850 °C (sintering), 950 °C (solid-solution), and 350 °C (aging). Comparing hot-press sintering (HPS) with spark plasma sintering (SPS) reveals distinct microstructure-property relationships in the Cu-0.9Be-1.0Ni alloy. At peak aging (350 °C, 240 min), the HPS and SPS alloys exhibit microhardness values of 268.8 HV and 282.5 HV, respectively. During aging process, the precipitation evolution sequence of both the HPS and SPS alloys is GP zone + γ″ + γ′ → γ″ + γ′ → γ′ → γ′+ γ. The HPS alloy exhibits a higher σ UTS of 860.76 MPa compared to the SPS alloy. Meanwhile, the HPS alloy exhibits significantly higher work-hardening index during homogeneous plastic deformation. This results from the finer grain structure of the HPS alloy and its distinct precipitation kinetics during subsequent aging compared to the SPS alloy. The Δ σ calculated for the HPS and SPS alloys at peak aging using the Orowan strengthening mechanism are about 492.2 MPa and 476 MPa (consistent with experimental data), respectively.