Effect of sintering conditions on the hardness of porous pure magnesium fabricated by MM-SPS process

Abstract

Pure magnesium (Mg) powders added 0.50 g of stearic acid were mechanically milled (MMed) using a vibration ball mill. The MMed powders were consolidated into bulk materials by the spark plasma sintering (SPS). Changes in hardness, solid-state reactions, thickness and internal structure of the SPS materials have been examined by hardness measurements, X-ray diffraction (XRD), vernier caliper and X-ray computed tomography (CT), respectively. The hardness of the SPS materials decreased with increasing sintering pressure and temperature. Minimum value of Vickers hardness was 17 HV. The formation of MgH₂ by solid-state reaction was observed during sintering. The maximum thickness of the SPS materials was 10.4 mm, and this value was a 46% increase compared to that of the MM 0 h thickness. The thickness of the SPS materials increased with increasing sintering temperature. No effect of sintering holding time on thickness of the SPS materials was observed. X-ray CT images showed that the pores of the SPS materials were generated in a flattened shape. The SPS materials densified up to 723 K, but expanded above 723 K during sintering.