Investigation Of Interfacial Structure And Performance Of AZ91D/6061Al Liquid-solid Diffusion-bonding

In order to "energy conservation and emissions reduction"，car engine block fromthe early cast iron to the present aluminum alloy, lightweight research has beencontinuing.Gradually to the development of lightweight vehicles, is make lightweightaluminum and magnesium alloy castings demand increases every year.The dissimilarmetal welding of magnesium, aluminum is a challenging task,the die casting technologyis used to cast the liquid magnesium alloy on the solid aluminum alloy surface,thedissimilar metal liquid-solid diffusion welding of magnesium/aluminum is a new kindof dissimilar metal welding process.the process provides a new way for mass productionof welding complex interface shape magnesium/aluminum dissimilar metal.The majordifficulty of aluminum alloy welding is its natural oxidation layer on the surface,it willhinder the mutual diffusion of magnesium alloy and aluminum alloy,then it is difficultto obtain a good metallurgical bonding.Firstly,we carried out surface treatment on thesolid aluminum alloy (6061) to remove the oxide film of surface,displace the film withthe zinc coated layer at the same time,Then cast the magnesium alloy (AZ91D) melt toaluminum alloy substrate.In this paper, liquid/solid composite technology (liquidmagnesium alloy package with solid aluminum cast liner process) to the development ofbi-metallic materials magnesium alloy/aluminum alloy(AZ91D/6061Al) composite,focus on the solid aluminum (liner) Surface treatment, and AZ91D/6061Al liquid/solidcomposite technology and the effect bi-metal interface on the organization andperformance of AZ91D/6061Al. The results showed that:1、Zincate process can be successfully deposited and coated on the surface of thealuminum substrate with a layer of Zn to protect the aluminum surface oxidated again.2、the surface treatment of6061Al aluminum alloy solid improved the wettabilitybetween the AZ91D/6061Al effectively.3、By controlling the complex process, microstructure and properties can bechanged to reduce cracking, porosity and thickness of the reaction layer.4、the diffusion of the bi-metallic element in interface show that there ismetallurgical combination here,there are three transition layer,the main alloy phase atthe interface are the eutectic structure of Mg17Al12phase and δ(Mg) phase，Mg17Al12phase，and Al3Mg2phase.5、With the measurement of HV,we found that the hardness of interface issignificantly higher than the both side， indicating that the liquid-solid bi-metallic composite formed metallurgical bond.