Papers by Author: Munekazu Ohno

Abstract: Al-coated Mg-Li alloy rods and plates having a homogeneous coating layer of 180μm in thickness have been produced by hot extrusion of Mg-Li alloy billets together with Al disks. The Al-coated Mg-Li alloy exhibits an excellent corrosion resistance in a weight-loss test with a 0.5 mass% HCl aqueous solution, and it has been revealed by a potentiometric corrosion test with a 3 mass% NaCl aqueous solution that the Al-coated Mg-Li alloy has the same electric potential as that of pure Al. Al-coated Mg-Li alloy sheets produced by hot forging of the extruded plates exhibits good elongation of 22 %, 40 % and 130 % at room temperature, 200 °C and 300 °C, respectively.

Abstract: Pure titanium and aluminum sheets were used to prepare titanium-aluminum diffusion couples. The diffusion couples were heated to temperatures 550, 575, 600, 625, 640, 650 and 700°C. SEM observations of the titanium-aluminum interface and EPMA results revealed that a TiAl₃ intermetallic layer has formed and thickened between the layers. Grain boundaries of the TiAl₃ compound, which were revealed by back-scattered electron imaging, indicated a size distribution across the layer. Finer grains which were located close to the titanium showed that TiAl₃ has nucleated at the Ti-TiAl₃ interface. Thus, the former grains which had formed close to the aluminum-rich side have grown and coarsened during annealing at high temperatures. Grain coarsening of TiAl₃ decreased the kinetics of the layer thickening.

Abstract: TiC−Fe system cermets and TiC−SUS310L (TiC−SS) system cermets with fully relative density have been produced from elemental powders via self-propagating high-temperature synthesis (SHS) reaction combined with pseudo-hot isostatic pressing. X-ray diffraction (XRD) analysis showed that the SHS products consist of TiC and the binder phase of Fe or SS. Metallographic analysis revealed TiC particles of several micrometer size were homogeneously dispersed in the binder phase. Regardless of differences in the binders, both cermets have similar tendencies: their relative densities increased and their hardness and compressive strengths decreased with increases in the volume fraction of either Fe or SS. In addition, the cermets used stainless steel as the binder had twice superior corrosion resistance to those used iron and also their hardness and compressive strength showed excellent values.