Effect of preparation technology on grain characteristics and mechanical properties of Cu-15Ni-8Sn alloy
The hardness,strength and elongation of as-cast,homogenizing annealed(850 ℃×8 h),forged,solution treated(840 ℃× 1 h)and aged(400 ℃×6 h)Cu-15Ni-8Sn alloy were compared,and microstructure and fracture surface morphology of the alloy under different process conditions were analyzed.The results show that the microstructure of the as cast alloy is well-developed dendrites.After homogenization annealing,the dendritic structure disappears and the lamellar structure completely dissolves in the copper matrix.After forging,the grain size of the homogenizing annealed alloy significantly decreases,with the average grain size decreasing from 58.78 μm to 4.22 μm,the tensile strength increases from 395.39 MPa to 659.50 MPa,and the grain refinement strengthening is the main strengthening mechanism.Due to the sufficient solution of solute atoms,the elongation of the solution treated alloy significantly increases to 46.7％.After further aging treatment,the tensile strength of the alloy increases to 802.50 MPa.
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