Compression Properties and Fabrication of Closed-Cell Metal Matrix Syntactic Foams Al₂O_3hs/AZ91D

Closed-cell metal syntactic foam is a new material consisting of hollow spheres embedded in metal matrix syntactic foams. These foams have good physical and mechanical properties and are increasingly used worldwide in industrial and high-tech fields. Magnesium matrix syntactic foams containing hollow Al₂O₃ spheres ((Al₂O_3hs)/AZ91D) were successfully fabricated by hot press sintering at different temperatures. The fabrication of Al₂O_3hs/AZ91D and the effect of sintering temperature on the microstructure and properties are reported in this paper. Additionally, sandwiched magnesium matrix syntactic foams were prepared by placing magnesium plates on both sides of the syntactic foam. Some Al₂O_3hs particles became filled with matrix particles during preparation. Thus, the actual density was greater than the theoretically calculated value and increases with increasing sintering temperature. Above 723 K, a brittle phase MgAl₂O₄ formed in Al₂O_3hs/AZ91D. The quasistatic and dynamic compressive strengths of Al₂O_3hs/AZ91D first increased and then decreased with increasing sintering temperature, and the maximums were 162 MPa and 167.87 MPa, respectively. Thus, this paper reports a new strategy for the controlled preparation of metal matrix syntactic foams with predetermined porosity. The results show that this strategy improved the performance of lightweight and high-strength syntactic foam materials and shows potential for further research.