Study On Interface Behavior Of Aluminum/zinc Laminated Composites Prepared By The Printing Casting Technology

The metal layered composite not only maintains the original characteristics of each layer,but also makes its physical,chemical and mechanical properties superior to that of a single metal.The production of layered composite materials makes the utilization of resources more reasonable and effectively solves the problems of energy shortage in China.In recent decades,metal layered composites have been applied in aerospace,petroleum,machinery,chemical industry,automobile,shipbuilding,building,power,electronics and other fields because of their excellent performance.There are many technologies for the preparation of metal layered composites,but they have their own shortcomings.The most important problem is complicated preparation technology,which is difficult to realize process production.Therefoer,those has restricted its large-scale input into industrial production.Our research group proposed the process of printing and casting to prepare metal layered composite and its process is roughly as follows: using the slot type printing injector to print different alloy melts to the die and make multilayer composite slab in the form of layered superposition.The technology not only improves the preparation efficiency of the laminated composite,but also has simple equipment and easy operation,so it is easy to realize the process of production.In this paper,A356/Zn and ZA27/A356 bimetal composite plates were successfully prepared by printing and casting process.Scanning electron microscope,electron probe and electronic universal testing machine were used to study the influence of process parameters,such as pouring order of alloy melt,pouring temperature of A356 aluminum alloy and mold temperature,on the interface structure and mechanical properties of bimetal composite plate.Finally,the following conclusions are reached:(1)there were gaps and other defects in the interface of Zn/A356 bimetal composite plate prepared in the case of A356 aluminum alloy was first poured after pouring Zn.After changing the casting sequence,metallurgical bonding of A356/Zn bimetal composite plate interface was achieved,and the interface could be distinguished from three area: I,II and III.There were gaps and other defects in the interface of A356/ZA27 bimetal composite plate prepared in the case of ZA27 zinc based alloy was first poured after pouring A356 aluminum alloy.After changing thecasting sequence,metallurgical bonding of ZA27/A356 bimetal composite plate interface was achieved.(2)the interface area II of A356/Zn bimetal composite plate is changed from smaller columnar dendrites or spheroidal crystals to larger columnar dendrites,and the size of silicon particles becomes smaller and the distribution is more dispersed,when the pouring temperature of A356 aluminum alloy is changed from 620 to 660?.(3)the number of primary ?-Al phase in I and II increases,and the width of I increases,and the lamellar spacing of eutectic structure in area III increases,when the die temperature is changed from 50 to 200?.The influence of mould temperature change on the interface width of A356/Zn bimetallic composite plate is more obvious than that of A356 aluminum alloy.(4)the concentration of aluminum in the interface area near the A356 aluminum alloy side is higher and the number of primary ?-Al is the most;the concentration of zinc element in the interface area near the pure zinc side is higher and the number?-Zn phase is the most.The aluminum element gradually decreases and the zinc concentration increases gradually from the I side to the III side.The amount of ?phase were producted due to peritectic reaction.The sequence of solidification in each region of A356/Zn bimetal composite plate is I,II and III.the order of the solidification of the A356/Zn bimetallic composite plate interface is: I,II,III.(5)area I hardness of A356/Zn bimetallic composite plate interface is the highest about 105 HV,III hardness is the lowest about 63 HV and area II the hardness is decreased from the regional I side to the III side;when the pouring temperature of A356 aluminum alloy changed from 620 to 660?,the slope of area II hardness curve decreased.When the mold temperature changed from 50 to 200?,the hardness of the interface area II increased.The change of mold temperature and pouring temperature had no effect on the hardness of the interface area I and II.The interface shear strength A356/Zn bimetallic composite plate in case of A356 aluminum alloy pouring temperature is 620? and mold pouring temperature is 50?,is the lowest about58MPa;the interface shear strength A356/Zn bimetallic composite plate in case of A356 aluminum alloy pouring temperature is 660? and mold pouring temperature is50?,is the highest about 158MPa;the shear strength of the two types of composite plates has little difference,and the shear strength is between 120~130,when the mold temperature is 50?,and the pouring temperature of A356 aluminum alloy is 660 and620?.The interface microhardness of the ZA27/A356 bimetallic composite plate isgradually increased from A356 side to the ZA27 side,and the shear strength of the interface is 122 MPa.