Pure magnesium (Mg) powders together with different amounts of process control agent (PCA) were mechanically milled (MMed) using a vibration ball mill. Stearic acid was used as process control agent (PCA) for the mechanical milling (MM) process. The MMed powders were consolidated into bulk materials by the spark plasma sintering (SPS). Changes in hardness and solid-state reactions of the SPS materials have been examined by hardness measurements and an X-ray diffraction (XRD), respectively. A maximum hardness value of 102 HV obtained in the SPS materials fabricated from MMed 24 h powders with PCA1.50 g at sintering temperature of 823 K for 60 min. Formation of MgO by solid-state reaction was observed for the SPS materials consolidated from MMed 24 h powders with PCA1.00 g and 1.50 g. The amount of MgO formation increased with increasing sintering time. No correlation was observed between MgO formation and hardness. The Vickers hardness of the SPS materials improved by increasing sintering temperature. However, no significant change in hardness and constituent phases was observed with increasing sintering time. Pure Mg of hardness can be improved by MM-SPS process.

Impact tests and tensile tests were conducted between 77 K and 450 K in order to elucidate the temperature dependence of absorbed-impact energy, yield stress, effective shear stress, activation volume, and activation enthalpy. The impact-absorbed energy decreased with decreasing test temperature, however, this alloy did not undergo low-temperature embrittlement although it has a bcc structure. Tensile tests showed changes in both the work-hardening rate and the temperature dependence of yield stress at approximately 150 K. This suggests a change in the mechanism behind the plastic deformation at the temperature. The temperature dependence of the activation enthalpy for dislocation glide suggests that the process of climbing over the Peierls potential (kink-pair nucleation) is the dominant mechanism for the dislocation glide from 150 K to 200 K, while the interaction between a dislocation and solute atoms dominantly controls the dislocation glide above 200 K. Superelasticity appears in stress-strain curves tested below 120 K, suggesting that the yielding is governed by transformation-induced plasticity below 120 K. The enhanced toughness at low temperatures in these alloys is discussed from the viewpoint of dislocation shielding theory.

Porous aluminum has lightweight and low density, with high shock absorption, sound absorption, and insulation properties, but generally has downward bending and tensile strengths. Improving its bending and tensile strengths is necessary for the industrial use of porous aluminum. In this study, composite materials with wire mesh inside porous aluminum were fabricated. By fabricating a composite material of porous aluminum and stainless steel wire mesh, we considered that the internal wire mesh could improve the tensile strength of the porous aluminum. The wire mesh was placed between precursors to fabricate the composite material of porous aluminum and stainless steel wire mesh. The precursors were heated and foamed, and pressed immediately after foaming. Scanning electron microscopy (SEM) showed no gaps at most boundaries between the porous aluminum and the wire mesh. It was also confirmed that there was no clear joint boundary between the porous aluminum foamed from the two precursors. Tensile test results showed that the tensile strength of the composite material in this study was the sum of the strength of the porous aluminum and the wire mesh, and that the strength was increased.