Study On The Uniformity Of Bonding Interface Of Cu/Al Layered Composite

As the core component of hydrometallurgical of zinc,the Cu/Al conductive head has been receiving extensive attention from all walks of life for its shear strength and interface resistivity.At present,the market has always used explosive welding and casting methods to prepare Cu/Al conductive heads.However,explosive welding and casting welding are limited by their own technology,and the preparation process is noisy,dangerous,and environmentally polluted.There are many holes in the interface of the composite material,crack defects are obvious,and the conductivity is poor,so that the composite material often explodes during the service process.In this paper,a vacuum hot-press diffusion method is introduced to prepare large-area Cu/Al composite materials,and a systematic study has been carried out on them Exploring appropriate combination of process parameters in the vacuum hot pressing diffusion method for the Cu/Al,such as temperature,time,pressure,etc.,and by adding CuZn alloy fiber to improve the interface and performance of the Cu/Al layered material,the uniformity of the interface is further improved,and the production efficiency of the composite material is greatly improved under the condition of obtaining a high-quality composite material.In this paper,under the conditions of Microstructure-properties-product,the mechanism of the influence of CuZn alloy fiber on the interface uniformity is explained,and the factors affecting the interface uniformity are deeply studied.The conclusions are as follows:Cu/Al composite material was prepared by hot-press diffusion method.The interface phase is generally divided into three layers:Al4Cu9,AlCu and Al2Cu phases.When the interface is below 18 μm,as the interface thickens,the shear strength gradually increases.When the interface width is greater than 18μm,the interface further thickens and the shear strength gradually decreases.The resistivity continues to increase as the width of the interface increases.As the bonding temperature increases,the number of vacancies in the copper-aluminum matrix increases,which is more conducive to the diffusion between atoms,The thermal fluctuation effect is more obvious at high temperature,and the transition frequency of copper and aluminum atoms increases faster,resulting in an increase in the diffusion coefficient.When the bonding temperature is 590℃ and the bonding time is 30 min,the interface width is about 18μm,the average shear strength,variance,and standard deviation are 61.64 MPa,18.70,and 3.75,respectively,and the resistivity is 24.26 × 10-9 Ω·m.The introduction of Zn element reduces the diffusion activation energy of Cu and Al elements,thereby promoting the mutual diffusion between Cu and Al elements,and promoting the metallurgical bonding of the interface at low temperature.The addition of CuZn alloy fiber makes the interface present a skeleton structure,promotes uniform diffusion of the interface,and improves the uniformity and reliability of the interface and properties of the Cu/Al composite material.When adding CuZn alloy fiber with a diameter of 0.253 mm,it is most suitable for the bonding of Cu/Al interface,As the pore diameter of the alloy fiber decreases,the content of Zn element per unit area increases,and the Cu/Al interface layer thickens,resulting in a decrease in interface bonding strength and an increase in resistivity.When the temperature is lower than 570℃,the interface forms a cellular framework structure;when the temperature reaches 590℃,the CuZn alloy gradually dissolves in the intermediate layer,and the interface gradually becomes flat;When the bonding temperature reaches 570℃ for 60min,a good and uniform composite material is obtained.At this time,the variance of the shear strength of the Cu/Al composite material is reduced from 18.7 to 1.6,and the standard deviation is reduced from 3.7 to 1.1.The improvement effect is obvious.Cu/Al interface cracks initiate and propagate from the intermediate layer(intermetallic compound),and gradually expand into the Al matrix.The ductile fracture prolongs the propagation path of the crack.The fracture mode that occurs in the aluminum matrix can be used as an important factor of shear strength.Enhanced mode.Therefore,the fracture mode is mainly a mixed mode of aluminum matrix fracture and IMC interlayer fracture.For Cu/Al composite materials,the connection temperature has a greater impact on the interface strength,and the connection time has a greater impact on the uniformity of the interface.Because the width of the intermetallic compound at the interface exhibits an exponential pattern with increasing temperature and a parabolic pattern with the extension of the connection time,the temperature has a greater influence on the width of the interface,thereby affecting the strength of the interface.The extension of the connection time makes the interface diffusion more fully.