Assessing Microstructural and Mechanical Characteristics of Ni/Az91 Composites Manufactured Using Hot Pressing Technique for Automotive Applications

Abstract

In the present study, AZ91 magnesium alloy matrix composite materials reinforced with nickel microparticles in different volumetric ratios were successfully manufactured via hot pressing technique. The density values, morphological properties, and room and high-temperature mechanical characteristics of the produced materials were analyzed in detail. In the composite specimens, it was determined that the density values increased linearly with the increase in reinforcement content, and that the actual density values were very close to the theoretical density values. The porosity was detected to be 2.74 % in the composite material containing the maximum amount of reinforcement. It was observed that nickel microparticles did not cause a significant change in the grain size of the matrix alloy at the micrometer-scale after hot pressing. In the microstructural analyses, the alpha-Mg, (3-Mg17Al12, gamma-Ni, and Mg2Ni phases were identified. Apart from these phases, no other phases were encountered in the morphological analysis. A good interface has been achieved between the matrix and the reinforcement phases, which is crucial for mechanical behavior. In mechanical tests conducted at different temperatures, it was found that the nickel reinforcement material significantly improved the compressive yield strength and compressive strength of the composite materials by 20 % and 69 %, respectively, at room temperature. In terms of elongation, it has resulted in a significant increase of 91 % compared to matrix alloy materials. The final characteristics of the composite materials are assessed to possess considerable potential for application in various fields, particularly in the automotive industry, where energy efficiency and low density are critical.