Effect of Yttrium on Cellular Precipitation Kinetics, Grain Growth Behavior and Mechanical Properties of High Strength and Toughness Cu-15ni-8sn Alloy

Abstract

The effect of yttrium on cellular precipitation kinetics, grain growth behavior and mechanical properties of Cu-15Ni-8Sn alloy is investigated. The results show that the added yttrium results in the formation of NiSnY and Ni2Y compounds, which increase the strength, refine the grains and slow down the grain growth rate of the Cu-15Ni-8Sn alloy. Also, the addition of yttrium changes the nucleation rate and crystal growth type of γ phase, postponing the cellular precipitation in the early stage of aging treatment. Compared with the peak-aged Cu-15Ni-8Sn alloy, the peak-aged Cu-15Ni-8Sn-0.2Y alloy possesses higher hardness and strength. The hardness increases from 348 HV to 372.2 HV, the yield strength increases from 960 MPa to 1098 MPa, the ultimate tensile strength increases from 1044 MPa to 1166 MPa. The optimal tensile strength of Cu-15Ni-8Sn-0.2Y alloy after solution and aging treatment is higher than that of other Cu-15Ni-8Sn-X (X is the microalloying element) alloys after solution and aging treatment in the previous study.

Keywords: Cu-15Ni-8Sn alloy, Yttrium, Cellular precipitation kinetics, Grain growth, Mechanical properties.