Metallurgical Interface of 7075/6061 Bimetallic Composite Ingot Casted by Semi-Solid Slurry and Molten Metal Pouring

摘要

The 7075/6061 bimetallic composite ingots were prepared by semi-solid/liquid method. The microstructure characteristics of composite ingots were studied, and the diffusion law of interface components was analyzed. The results show that the semi-solid/liquid composite of 7075 and 6061 can be realized under the conditions of casting temperature of 983 K, semi-solid heating temperature of 918 K, holding time of 1h, and rapid water cooling. The obtained composite ingot has a layered distribution characteristic of "semi-solid microstructure/dendritic structure". The interface is clear, continuous, and free of impurities. From the interface to the semi-solid side, it shows such a pattern of change: "Dendritic structure" → "Semidendritic and hemispherical" → "Globularization". Through the observation of the microstructure and the analysis of the components, the semi-solid/liquid composite mechanism is discovered to be a combination of fusion bonding and diffusion bonding.