Research On Annealing Hardening Phenomenon And Strengthening Mechanism Of High Strength Cu-Ni-Si Alloy

Cu-Ni-Si alloy is widely used in the field of integrated circuit lead frames becau se of high strength,good wear resistance,good conductivity.In this paper,the effect of alloy composition on the annealing hardening behavior of Cu-Ni-Si alloy,the effect of cold rolling and heat treatment on the structure and properties of Cu-Ni-Si alloy,and the effect of annealing The effect of hardening behavior by the addition of Al element on Cu-Ni-Si alloy were studied.The composition of Cu-Ni-Si alloying elements was designed.The result of the mass ratio of Ni/Si and the content of Ni and Si on the annealing hardening behavior of Cu-Ni-Si alloy was studied.The annealing hardening mechanism of Cu-Ni-Si alloy was the strengthening of nano-second phase particles.After annealing,a continuous or semi-continuous network phase appeared in the matrix microstructure of the alloy,and a large number of disc-shaped ?-Ni3Si nano-precipitated particles were produced.The strengthening mechanism was that amplitude modulation decomposition occurs during the annealing process.A phase enriched with solute atoms appeared in the alloy,forming a supersaturated solid solution which precipitated nanoparticles to cause strengthening.The influence of cold rolling and heat treatment process on the structure and mechanical properties of Cu-Ni-Si alloy was studied.The effects of casting +annealing,casting+ cold rolling+annealing,casting+solid solution+ cold rolling+annealing and casting+cold rolling+solid solution+annealing on the properties of Cu-3Ni-0.6Si alloy were compared and analyzed.It was found that casting+Cold rolling+annealing process had better comprehensive properties,relatively high tensile strength and electrical conductivity,and relatively low elongation.When the.cold rolling deformation was 70%,the alloy had better comprehensive properties.The tensile strength,elongation and electrical conductivity of Cu-3Ni-0.6Si alloy were 696MPa,3.6%,40.54%IACS,respectively.The influence of Al element,cold rolling and heat treatment process on the structure and mechanical properties of Cu-Ni-Si alloy was studied.It was found that adding a small amount of Al ele ment can increase the annealing hardening effect of Cu-Ni-Si alloy,but significantly reduce the conductivity.The highest hardness of the Cu-3Ni-0.6Si-1Al alloy were found.The hardness increased from 73HV in the as-cast state to 213HV in the as-annealed state,an increase of 191%.