Pure magnesium powders together with different amounts of process control agent (PCA) were mechanically milled (MMed) using a vibration ball mill. Stearic acid was used as PCA for the mechanical milling (MM) process. MMed powders were consolidated into bulk materials by spark plasma sintering (SPS). Changes in hardness and solid-state reactions of the MMed powders and the SPS materials have been examined by hardness measurements and an X-ray diffraction, respectively. No solid-state reaction was observed in the MMed powders even when the amount of PCA was increased. At PCA0.50 g, the Vickers hardness of the MMed powders and SPS materials did not improve with increasing a MM processing time. A maximum hardness value of 89 HV obtained in the SPS materials fabricated from MMed 24 h powders with PCA1.50 g. 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. Formation of MgO was observed in the SPS materials by increasing the amount of PCA without heat treatments. Enhanced hardness of SPS materials could be attributable for both volume fraction of MgO and sintering temperatures.

Powders of functional materials with tri-axial magnetic anisotropy can be bi-axially aligned under modulated rotating magnetic fields (MRFs) in principle. Magnetic alignment is a material production process without highly oriented templates and a room temperature process. However, in the case of MRF, rotation of magnetic field is required for the generation of MRF, which looks inappropriate for continuous production process along a linear direction with linear motion apparently. In this article, development and details about the equipment of linear drive type MRF generation system are described. First topic is principle of MRF and design of permanent magnet array for generate of MRF. Second topic is the bi-axial magnetic alignment of practical rare-earth-based cuprate superconductors using the equipment. Final topic is the current status on design of the magnet arrays to generate higher magnetic flux densities.

Flash sintering was firstly reported in 2010 by a research group of Raj et al. at Colorado University. Since then, flash sintering has attracted attention as an innovative sintering method that uses the steep power spike, generated when ceramic green compact is heated while an electric field, is applied to densify ceramic green compact in an instant. However, there are several technical challenges that must be overcome before flash sintering can be used as a practical sintering method. This paper outlines the problems and improvements related to flash sintering from a viewpoint of sintering method, and introduces the improved flash sintering noted as shrinkage-rate controlled flash sintering developed by the author.

Flash events, where high-temperature dynamics such as sintering, superplasticity, and crack healing of ceramics are significantly promoted by electric fields and/or currents, have been attracting scientific and technological interests. In this review, anomalous mechanical responses in 8 mol% yttria-stabilized zirconia flash-processed using an AC electric field are described. The dynamic and quasi-static mechanical properties before and after flash processing were evaluated via sound velocity and nanoindentation measurements to characterize the mechanical responses attributed to flash-induced defects. Rate-dependent elastic softening (i.e., the slower the loading rate, the lower the indentation modulus) was observed in the quasi-static range after flash processing, while a negligible change was confirmed in the dynamic elastic behaviors even after flash. Such anomalous mechanical responses in the flash-processed sample are characterized as anelasticity (i.e., viscoelasticity or pseudoelasticity in other terms), which can be attributed to stress-induced and thermally activated recoverable motions of point defect dipoles induced via flash processing. This anelastic behavior may be of importance for understanding the nature of flash-induced defects which athermally contribute to the enhanced diffusion during flash events.