The Investigation On Properties Of The Cu Matrix Composites Processed Via Accumulative Roll Bonding

Cu is widely used because of its the high conductivity,but it is difficult to meet the demand of high-strength conductive applications due to its low strength.Therefore,people use composite rolling to combine Cu with other metals to obtain high-strength Cu-based composites with a characteristic size modulation ratio of 1.During the loading process,the unconformity of the two sets of elements causes the shear instability of the composite to fail.Recently,studies have shown that the strengthening of back stress generated by a heterostructure or a gradient layer structure during deformation can simultaneously increase the strength and plasticity of the material.Therefore,in this paper,a layered composite with uneven thickness is prepared by stacking method to improve the mechanical properties of the composite.At the same time,the high thermal conductivity of Cu makes it ideal for electronic packaging materials,but its thermal expansion coefficient limits its application.It is expected to be suitable for high thermal conductivity and low expansion material electronic packaging by utilizing the low expansion property of Invar to laminate it with Cu.In addition,the low expansion mechanism of Invar is still controversial.Recently,the inhomogeneous composition of Invar is found.It is speculated that the Invar effect may be due to the constrained martensitic transformation of the nano-domains with uneven composition during the cooling process.Therefore,Cu and FeNi are prepared by stack rolling to prepare a nanocomposite,and it is desirable to utilize Cu to constrain the martensitic transformation of nanoscale FeNi to obtain low expansion characteristics.In this paper,metal Cu and Nb sheets are composited by stack rolling.By adding Cu and Nb sheets of initial thickness during each stacking,a multi-scale sheet composite is finally obtained.Cu and Nb sheets having thicknesses of about 90μm,12μm,2μm,and500 nm were simultaneously present in the Cu/Nb-1-4 composite after four times of lamination.The tensile test shows that the tensile strength of the composite is 420 MPa,the tensile plasticity is up to 11%,and the back stress is strengthened by about 300 MPa,and the%IACS reaches 65.31%IACS.In the Cu/Nb-2-3 composites,there are two kinds of Cu and Nb sheets with thicknesses of about 2μm and 200 nm.Tensile tests show that the tensile strength of the composites reaches 527 MPa and the tensile ductility is about At 5.2%,its%IACS reached 66.4%IACS.The multilayer Cu/FeNi₃₆ and Cu/FeNi₁₁ composites were prepared by the rolling method.The Cu₈₀Fe_xNi_20-x alloy was prepared by melting and the thermal expansion properties and mechanical properties of the composites were studied.After three times of rolling,the Cu and FeNi sheets in the composite have a scale of about 500 nm.For Cu/FeNi₃₆ composites,the thermal expansion coefficient increases with the increase of the number of rolling,and when the temperature is lower than 150°C,the thermal expansion coefficient of the primary rolled sheet is 2.08×10^-6/°C,which is close to the expansion coefficient of FeNi₃₆.The thermal expansion coefficients of the secondary and tertiary rolled sheets are 5.96×10^-6/°C and 6.95×10^-6/°C,respectively.For Cu/FeNi₁₁composites,the thermal expansion coefficient increases with the increase of the number of times of lamination during phase change.