Study On The Thermo-mechanical Treatment And Hot Deformation Behavior Of Cu-4.5 Wt.% Ag Alloy

With the development of information and intelligent society,higher requirements are put forward for the performance of Cu alloy materials in China,such as high magnetic field materials,rotor coils of UAV and robots.The alloy should have high strength and high conductivity at the same time,optimizing the casting method and processing technology is of great significance for the preparation of high strength and high conductivity Cu Ag alloy.The oxygen content of as-cast Cu-4.5 wt.%Ag alloy prepared by vacuum horizontal continuous casting is about 2.4 ppm,the strength and electrical conductivity is 214.3 MPa and 96.8%IACS.After solid solution and peak aging,the strength of the alloy increased to 262.4 MPa,and the conductivity increased to98.4%IACS.Since there are a large number of supersaturated solid solution Ag atoms in the as-cast Cu-4.5 wt.%Ag alloy of vacuum horizontal continuous casting,the aging precipitation strengthening effect is significant when peak aging treatment is directly carried out without solid solution treatment.After cold drawing,the precipitates were elongated,forming fine Ag fibers,which can produce precipitation strengthening and promote dislocation strengthening,improving the strength of the alloy.In summary,Cu-4.5 wt.%Ag alloy reaches strength of 830 MPa and conductivity of 85%IACS by"vacuum horizontal continuous casting-peak aging-cold drawing"process.The precipitates in the aged Cu-4.5 wt.%Ag alloy greatly improves the work hardening ability of the alloy and imple the texture of the deromed alloy transform to<111>texture quikly.For alloy without aging,its texture is mainly<100>texture with higher Schmid factor.And after the deformation strain reaches 2.68,the alloy undergoes dynamic recovery and recrystallization,resulting in the offset of softening effect and work hardening effect,thus strength remain unchanged as deformation continues.After pre deformation,the alloy recovers and recrystallization accompanied with Ag precipitation.Intermediate heat treatment can significantly improve the plasticity and conductivity of the alloy,but the lower the strength of the alloy.With the increase of heat treatment time,the consumption of dislocations in the alloy matrix increases and the size of precipitates becomes coarse,which slower the propagation of dislocations and result in lager spacing and size of Ag fibers,reducing dislocation and precipitation strengthening effect.Therefore,short time intermediate heat treatment is more conductive to the preparation of Cu-4.5 wt.%Ag alloy products.In this paper,the hot deformation behavior of the alloy was simulated by MMS-100 equipment,and the stress-strain curve of the alloy was obtained.By constructing the flow stress constitutive equation and hot processing map of the alloy,the optimal process deformation temperature and strain rate for hot deformation of Cu-4.5 wt.%Ag alloy were found to be 800-850? and 0.01?0.1 s^-1.