This study aims to establish fundamental knowledge for online non-destructive inspection in the laser quenching process utilizing acoustic emission. Acoustic emission is the transient elastic wave phenomenon due to release of strain energy in a solid material. And it is well known that the martensitic transformation can induce the acoustic emission. In this study, the acoustic emission monitoring of martensitic transformation during laser quenching experiment was conducted with the chromium molybdenum carbon steel (SCM440 in Japanese Industrial Standards) as the specimen. The experiment was carried out with seven kinds of laser irradiation power for different volume generation of heat-affected zone. After experiment, the martensite structure was confirmed at the heat-affected zone and the volume of the martensite structure within the zone was estimated. Only the specimen irradiated by the lowest laser power had no martensite structure. The acoustic emission waves were analyzed using parameters that showed the generation time duration and scale of source phenomenon. As a result, the relationship between the volume of martensite structure and information of acoustic emission was positive. It was suggested that the acoustic emission monitoring have application for the online non-destructive inspection for the laser quenching process.

Pure magnesium and Mg-Y alloy single crystals were subjected to three-point bending tests to investigate the effect of crystal orientation and yttrium on bending deformation behavior. Specimens whose neutral planes are parallel to (0001) and neutral axes are [1120] deformed due to basal slips and showed a gull-shape. Their bending yield stresses increased by addition of yttrium and were controlled by the shear stress on the basal plane. Conversely, when neutral planes are parallel to (1100) and neutral axes are [1120], the specimens deformed due to {1012} twins occurred in the compression side, basal slips within the twins and finally showed a V-shape. In Mg-Y alloys, first order pyramidal <c+a> slips (FPCS) and {1011}-{1012} double twins were also activated in the tension side. Their bending yield stresses and bending ductility increased by yttrium addition. Strain induced by {1011}-{1012} double twins in the tension side was very low. FPCS was found to be activated by addition of yttrium and to increases bending ductility.

There is a possibility that the cinnabar (HgS) pigment used in the Takamatsuzuka tumulus was dug from the old Yamato mine. To search for a key to the solution, the microstructures of a cinnabar ore produced in the old Yamato mercury mine has been investigated. The specimen was taken from an old stockpile at the mine. An X-ray diffractometer, a scanning electron microscope, a transmission electron microscope, and an energy dispersive X-ray spectrometer were used to clarify the microstructures. The ore contains HgS as the main mineral, and αSiO₂, cristobalite (SiO₂), augite, kaolinite, albite and other minerals were detected. HgS crystals are buried in the vacant space (fissure) of the ore, and the crystals are distributed similarly to a chain of islands. The size of an αSiO₂ hexagonal column found in the ore is 5-10 µm. HgS contains Si, Al, and Fe as impurity.

Porous aluminum is a porous material with pores inside. Therefore, compared to aluminum alloy, it is superior in light weight, shock absorption, heat insulation, sound absorption, etc., and it can be expected to be applied to industrial parts. Since porous aluminum has different properties depending on the type of base material and porosity, it is possible to fabricate functionally graded porous aluminum by combining porous aluminum with different properties. The purpose of this study is to optimize the fabrication of functionally graded porous aluminum. Optimization criteria include observation of foaming behavior of precursor and temperature – time relationship during foaming process.