凝固速度和时效处理对高强高导Cu-3.2Ni-0.7Si合金组织与性能的影响*

Influences of cooling rate and aging on the microstructure and property of Cu-3.2Ni-0.7Si alloy*

摘要:

通过单辊旋淬快速凝固技术制备Cu-3.2Ni-0.7Si（wt%）合金薄带。研究了不同旋淬速度（凝固速度）和时效处理对合金微观组织、导电率和力学性能的影响。结果表明，随着凝固速度的增大，铸态合金的晶粒明显细化，导电率降低，显微硬度和拉伸强度升高。铸态合金在同一温度进行时效处理，随着时效时间的增加，合金的电导率呈升高趋势，而合金的显微硬度和拉伸强度先升高后降低。铸态合金的导电率随凝固速度的增大而降低是基体晶格畸变程度增大所致；合金时效处理后导电率升高是由于第二相析出明显消除晶格畸变的结果。铸态合金显微硬度和拉伸强度随凝固速度增大而升高是细晶强化的结果；时效处理后，合金的显微硬度和抗拉强度明显提高是第二相强化的结果，而过度时效导致显微硬度和拉伸强度降低的主要原因是第二相的粗化团聚所致。

Abstract:

Cu-3.2Ni-0.7Si (wt%) alloy ribbons were prepared by single roller melt-spinning at different rotating speeds. The influences of cooling rate and aging on the electronic conductivity and mechanical properties of Cu-3.2Ni-0.7Si (wt%) alloy were investigated. The refinement of the solidified microstructures is distinctly observed with increasing of the cooling rate, which is responsible for the decrease of the electronic conductivity and increase of the microhardness and the tensile strength. During aging of the as-quenched alloy at a temperature, the electronic conductivity increases with lengthening of the aging time. However, the tensile strength and the microhardness first increase with lengthening of the aging time, and then decrease after reaching peak values. The considerable decrease of the electronic conductivity with increasing of cooling rate is due to the severe lattice distortion. However, the electronic conductivity considerably increases due to aging, which is attributed to the recovery of the distorted lattices. The increases of the microhardness and the tensile strength of the as-quenched alloy are due to the strengthening effect of refinement. The increases of the microhardness and the tensile strength due to aging are attributed to the strengthening effect of the randomly distributed second phase in the matrix. However, the microhardness and the tensile strength tend to decrease after reaching peak values with lengthening of the aging time, which is due to the growth and agglomeration of the precipitated second phase.