Microstructural and Mechanical Behavior Investigations of Nb-Reinforced Mg–Sn–Al–Zn–Mn Matrix Magnesium Composites

This research focuses on the fabrication and characterization of TAZ532-xNb composites, employing high-purity, micron-sized powders of Mg, Sn, Al, Zn, Mn, and Nb as the raw materials. These powders were subjected to a paraffin coating process aimed at mitigating oxidation. The formation of composites was achieved via hot pressing and was followed by surface preparation and analysis using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). An X-ray diffraction (XRD) study was conducted to identify the microstructural phases. Quantitative assessments including the theoretical density, actual density, and relative density were computed, and their fluctuations in relation to the increasing Nb reinforcement ratio were scrutinized. Furthermore, the mechanical attributes of the composites, such as hardness and tensile strength, were assessed via experimental procedures. The absence of oxygen-related peaks in the XRD patterns endorsed the successful execution of the paraffin coating technique and protective gas atmosphere during sintering. The detection of α-Mg, Mg2Sn, MgZn, Mg17Al12, and Nb phases within the Nb-reinforced composite patterns authenticated the formation of the intended phases. Notably, the relative density values of the composites surpassed 95%, indicating efficient sintering. SEM results disclosed a densely packed microstructure, with Nb reinforcement particles evenly distributed along the grain boundaries, devoid of particle clustering or significant grain growth. These composites manifested exceptional wetting characteristics, which can be attributed to the employment of Mg alloy as the matrix material. EDS data confirmed the proportions of Nb within the composites, aligning with the quantities incorporated during fabrication. The composites showcased an increase in microhardness values with the escalating Nb reinforcement ratio, credited to the harder constitution of Nb particles in comparison to the matrix alloy. Concurrently, tensile strength showed a significant improvement with the increment in Nb reinforcement, while elongation values peaked at a specific Nb reinforcement level. The positive evolution of tensile strength properties was ascribed to the escalated Nb reinforcement ratio, grain size, and consequent higher sample densities.