| The W-Cu composites have high thermal conductivity and good electrical conductivity,and it have similar coefficient of thermal expansion with semiconductor chips.So it is widely used in electronic packaging materials.The W-Cu alloy sheet fabricated by infiltration methods does not meet the requirements of the electronic packaging materials,for it has larger thickness size,lower density.In this paper,the effects of temperature and strain rate on the stress of W-Cu20 alloy were investigated by a thermal simulation compress test,and the reason of deformation mechanism of W-Cu alloy were reason.Obtain the optimum hot-rolling process through thermal simulation compression test.The W-Cu20 thin sheets with full dense were successfully prepared by hot pack-rolling process using the optimal parameters,and the total compression deformation was as high as 75%.The structure evolution and phase composition of W-Cu20 alloy were analyzed by scanning electron microscope(SEM)and X-ray diffraction(XRD).And the density,mechanical properties and thermal properties of W-Cu20 alloy are tested by density balance,micro hardness tester,electronic universal testing machine,laser thermal conductivity measuring instrument,thermal expansion instrument,etc.The results show as follows:1.The flow stress and peak stress increase greatly with decrease of deformation temperature and increase of strain rate.When the strain rate is constant and the temperature is850?,the W-Cu20 alloy has slightest edge crack;when the deformation temperature is constant and the strain rate is 0.1 s-1,the W-Cu20 alloy has slightest edge crack.Based on the above results,the optimum hot-rolling process is the temperature of 850?and strain rate of0.1 s-1.The dominant edge fracture mode is W-Cu interface separation.2.The W-Cu20 thin sheets with full dense and free of cracks were successfully prepared by hot pack-rolling process using the optimal parameters.with the increase of compression deformation,the most of W particles are extended along rolling direction.Some W particles is broken into small particles under the large rolling force.The relative density and hardness increases significantly with increasing pack-rolling reduction rate.The highest values of relative density and hardness is 99.8%and 457 HV respectively after a total thickness reduction of 75%.with the increase of compression deformation,the tensile strength of W-Cu20 alloy plate increase,and the elongation decrease.The tensile strength and elongation of W-Cu20 alloy plate is 852.42MPa and 3.12%respectively after a total thickness reduction of 75%.The fracture morphology is composed of W-Cu binder interface separation,breakage of W particles,transgranular cleavage of W particles and tear ridge of Cu phase,which is a typical brittle fracture features macroscopically.3.XRD test shows that there is no new phase in the W-Cu20 alloy sheet after pack-rolling process.But with the increase of pack-rolling reduction rate,all the diffraction peaks of W and Cu phase have evidently moved to lower-angle region.The interplanar spacing increase obviously with increasing pack-rolling reduction rate.The large rolling force of W-Cu composites plate result in lattice distortions of W and Cu phase and dislocation density increase.The coefficient of thermal expansion decreases significantly with increasing pack-rolling reduction rate.The coefficient of thermal expansion is 7.19×10-6 K-1 after a total thickness reduction of 75%.The thermal conductivity,electrical conductivity decreases significantly with increasing pack-rolling reduction rate.The thermal conductivity and electrical conductivity is only 131.09 W/m·k and 32.41 IACS%respectively after a total thickness reduction of 75%. |
PDF Full Text Request