Fabrication and microstructural analysis of 3A21/7075 aluminum alloy cladding material based on impact jet solid–liquid compound casting

Abstract

To solve thickness problem for high-strength aluminum alloy used as plastic mold materials and eliminate oxide film on the surface of aluminum alloy, a new compound casting, namely impact jet solid–liquid compound casting, was developed to fabricate 3A21/7075 aluminum alloy cladding material. Then, optical microscope (OM), electron-backscattered diffraction (EBSD) technique, and transmission electron microscope (TEM) together with energy-dispersive spectrometer (EDS) were used to analyze microstructure of 3A21/7075 aluminum alloy cladding material. The OM and EBSD results showed that the 3A21/7075 aluminum alloy cladding material was composed of 3A21 cladding layer, fusion zone (FZ), heat-affected zone, and 7075 matrix. The grain morphology on both sides of FZ had great differences. Moreover, the TEM and EDS results showed that the 3A21 cladding layer showed a bulk phase and lots of fine and dispersed granular phases, while the 7075 matrix appeared undetermined strip phases and amounts of fine and dispersed rod-like phases. Moreover, FZ existed a great deal of fine and dispersed granular phases and rod-like phases. The 3A21/7075 aluminum alloy cladding material could effectively solve the problems mentioned above and the in-depth analysis of microstructures of 3A21/7075 aluminum alloy cladding material was of great importance in terms of engineering value and academic significance.