Minor-alloyed Cu-Ni-Si alloys with high hardness and electric conductivity designed by a cluster formula approach

摘要

Cu-Ni-Si alloys are widely used due to their good electrical conductivities in combination with high strength and hardness. In the present work, minor-alloying with M =（Cr, Fe, Mo, Zr） was conducted for the objective of further improving their hardness while maintaining their conductivity level. A cluster-plus-glue-atom model was introduced to design the compositions of M-alloyed Cu-Ni-Si alloys, in which an ideal composition formula[（Ni,Si,M）-Cu12]Cu3（molar proportion） was proposed. To guarantee the complete precipitation of solute elements in fine δ-Ni2 Si precipitates, the atomic ratio of（Ni,M）/Si was set as 2/1. Thus the designed alloy series of Cu93.75（Ni/Zr）3.75Si2.08（Cr/Fe/Mo）0.42（at%） were arc-melted into ingots under argon atmosphere, and solidsolutioned at 950 ℃ for 1 h plus water quenching and then aged at 450 ℃ for different hours. The experimental results showed that these designed alloys exhibit high hardness（HV＞ 1.7 GPa） and good electrical conductivities（≥ 35% IACS）. Specifically, the quinary Cu93.75Ni3.54Si2.08（Cr/Fe）0.42Zr0.21 alloys（Cu-3.32 Ni-0.93 Si-0.37（Cr/Fe）-0.30 Zr wt%） possess both a high hardness with HV = 2.5-2.7 GPa, comparable to the highstrength KLFA85 alloy（Cu-3.2 Ni-0.7 Si-1.1 Zn wt%,HV= 2.548 GPa）,and a good electrical conductivity（35-36% IACS）.