Investigations on physical and mechanical properties of Mg composites and foams fabricated by powder metallurgy using NaCl

Abstract

The demand for metallic foams is increasing rapidly because of their very low density, high heat dissipation ability, high vibration damping capacity, and high energy absorption capacity. In the present work, Mg composites and foams are prepared using salt as space holder material using the powder metallurgy technique. Salt in different volume fractions (0 %, 25 %, 50 %, and 75 %) was mixed with Mg, and Mg/salt composites were fabricated. Density, porosity, and hardness of fabricated Mg/salt composites were investigated. Then, the sintered Mg/salt composites were dipped in water for the dissolution of salt. Density, porosity, and compressive strength of fabricated foams were investigated. The density and hardness of Mg/salt composites increased with an increase in the volume fraction of salt. The highest density (1.93 g/cc) and hardness (26 BHN) were obtained for Mg/salt composite fabricated using 75 vol% of salt. While for Mg foams, porosity increased with an increase in the volume fraction of salt and the highest porosity of 64 % was observed in Mg foam fabricated using 75 vol% of salt. On the other hand, compressive strength decreased rapidly with an increase in the volume fraction of salt. The compressive strength of Mg foam fabricated using 75 vol% of salt was only 3.44 MPa, therefore not suitable for most industrial applications. But, for Mg foam fabricated using 25 vol% of salt, comparatively high compressive strength (22.5 MPa) and high porosity (36 %) were obtained. Because of their very low density (1.15 g/cc) and sufficient strength, fabricated Mg foams can be used for various applications in automobiles and other industries.