Mechanical properties and fracture behavior of Cu-0.84Co-0.23 Be alloy after plastic deformation and heat treatment were comparatively investigated.Severe plastic deformation by hot extrusion and cold drawing was adopted to induce large plastic strain of Cu-0.84Co-0.23 Be alloy.The tensile strength and elongation are up to 476.6 MPa and 18%,respectively.The fractured surface consists of deep dimples and micro-voids.Due to the formation of supersaturated solid solution on the Cu matrix by solution treatment at 950℃for 1h,the tensile strength decreased to271.9 MPa,while the elongation increased to 42%.The fracture morphology is parabolic dimple.Furthermore,the tensile strength increased significantly to 580.2 MPa after aging at 480℃ for 4h.During the aging process,a large number of precipitates formed and distributed on the Cu matrix.The fracture feature of aged specimens with low elongation(4.6%) exhibits an obvious brittle intergranular fracture.It is confirmed that the mechanical properties and fracture behavior are dominated by the microstructure characteristics of Cu-0.84Co-0.23 Be alloy after plastic deformation and heat treatment.In addition,the fracture behavior at 450 ℃ of aged Cu-0.84Co-0.23 Be alloy was also studied.The tensile strength and elongation are 383.6 MPa and 11.2%,respectively.The fractured morphologies are mainly candy-shaped with partial parabolic dimples and equiaxed dimples.The fracture mode is multi-mixed mechanism that brittle intergranular fracture plays a dominant role and ductile fracture is secondary. Mechanical properties and fracture behavior of Cu-0.84Co-0.23 Be alloy after plastic deformation and heat treatment were comparatively investigated. Thick plastic deformation by hot extrusion and cold drawing was adopted to induce large plastic strain of Cu-0.84Co-0.23 Be alloy. The tensile strength and elongation are up to 476.6 MPa and 18%, respectively. The fractured surface consists of deep dimples and micro-voids. Due to the formation of supersaturated solid solution on the Cu matrix by solution treatment at 950 ° C for 1h, the tensile strength decreased to 271.9 MPa, while the elongation increased to 42%. The fracture morphology is parabolic dimple. Fluorrthermore, the tensile strength increased significantly to 580.2 MPa after aging at 480 ° C for 4 h. During the aging process, a large number of precipitates formed and distributed on the Cu matrix. The fracture feature of aged specimens with low elongation (4.6%) exhibits an obvious brittle intergranular fracture. It is confirmed that the mechanical properties and fracture behavior are dominated by the microstructure characteristics of Cu-0.84Co-0.23 Be alloy after plastic deformation and heat treatment. In addition, the fracture behavior at 450 ° C of aged Cu-0.84Co-0.23 Be alloy was also studied. tensile strength and elongation are 383.6 MPa and 11.2%, respectively. The fractured morphologies are mainly candy-shaped with partial parabolic dimples and equiaxed dimples. The fracture mode is multi-mixed mechanism that brittle intergranular fracture plays a dominant role and ductile fracture is secondary .