Synthesis, Characterization and Mechanical Properties of AA7075 Based MMCs Reinforced with TiB2 Particles Processed Through Ultrasound Assisted In-Situ Casting Technique

Abstract

AA7075/TiB2 composites have been synthesized through both in situ salt-melt reaction method and ultrasound assisted in situ process. Microstructural studies reveals that ultrasound assisted in situ method improves the dispersion of TiB2 particles and reduces the porosity level. Moreover, the ultrasonic treatment refines the reinforcement particle size along with improvement in particle dispersion. The mechanical property assessment confirms that ultrasonic treatment improves the mechanical properties of composite. The hardness of the AA7075 alloy is increased from 55 HV to 74 HV by the addition of 5% TiB2 particles and it further increased to 82 HV by ultrasonic treatment. A similar trend is also observed when weight percentage of particles increases to 7.5%. Addition of 5% in situ TiB2 particles increases the ultimate tensile strength of AA7075 alloy by 60 MPa and it is further enhanced by 80 MPa upon ultrasound assisted process. Composites have shown a small reduction in ductility when compared to un-reinforced alloy, though 81% ductility of matrix alloy has been retained. Similar trend has been observed in composites fabricated using ultrasonic assisted casting.