Spark plasma sintering of a novel Mg-0.7Ca alloy: A comprehensive study

Abstract

Light-weight Mg-based alloys have gained attention owing to their various applications in engineering and biomedical fields. Recent advancements in modern powder metallurgy techniques, such as spark plasma technique (SPS), have enabled achieving near-net-shape products with tailored properties and decreased in-process oxidation. However, improving their mechanical and physical properties require further enhancement. In this study, a novel Mg-0.7Ca alloy was produced using SPS process. The effects of process parameters such as sintering time and additive type on the microstructural evolutions, phase arrangements, and mechanical and physical properties of the consolidated materials were investigated through various characterization techniques. Full-dense samples were produced from 60-minute ball-milled powder mixtures through spark plasma sintering at 420 °C for 7, 10, and 13 min under 38 MPa of externally applied pressure. The obtained samples were then characterized using Field Emission Scanning Electron Microscopy (FESEM), Electron Backscatter Diffraction (EBSD), X-ray Energy Dispersive Spectroscopy (EDS), and X-ray Diffraction (XRD) analysis methods, as well as mechanical tests including compression strength and micro-hardness measurements. The results indicated that while improved densification behavior is observed in paraffin-contained samples, relatively better compression properties are achieved in starch-contained alloys. It is also found that the phase arrangement of the starch-contained samples includes higher fractions of the secondary phases such as oxides and residual carbons, which can positively affect the mechanical strength, despite decreased hardness. The microstructural characterizations showed an intensified thermomechanical response of the materials in both groups via increased sintering time. However, the competition between the influencing parameters causes scattered strengthening behavior and texture in the consolidated samples. Detailed discussions about the densification behavior, texture, and obtained characteristics were also included.