Magnetic properties of soft magnetic materials under stress are important, however, they have not fully understood. We measured magnetization curves of soft magnetic alloy sheets, electrical steel sheets and nanocrystalline alloys, with positive magnetostriction, under compression. The stress was applied in the same direction of magnetic fields. Magnetization curves have smaller slopes due to anisotropy of magnetoelasticity. The anisotropy energy was estimated from the magnetization curve. And we could obtain a stress dependence of the anisotropy energy; a relation between anisotropy energy and stress was a straight line. The slope of the line correlates magnetostriction values.

We devised a magnetic domain model under compression; a magnetization process on the model is a 90 degree magnetic domain wall movement; the relation between anisotropy energy and stress could be formulated. The magnetostriction values estimated from the line slope coincided with experimental ones. Therefore, it can be thought that the magnetization process under compression is mainly 90 degree domain wall movements.

The effects of elapsed time following gas metal arc welding (GMAW) on the static strength of lap fillet-welded joints were investigated using a static tensile test. It was observed that the static joint strength did not exhibit a time dependency for cases where the fracture was located in each base metal or the softened heat affected zone (HAZ). In addition, the static joint strength was not observed to have a time dependency for cases where a wire with low-hardness weld metal was used and where the fracture was located in the weld metal. However, the static joint strength was low immediately after welding, and increased over time when a wire with high-hardness weld metal was used. It was found that diffusible hydrogen that entered the weld metal during arc welding and was emitted over time was the cause of the time dependency of joint strength. High-hardness weld metal was sensitive to diffusible hydrogen; therefore, time dependency was observed only when wires with high-hardness weld metal were used and the fracture positions were located in the weld metal during tensile tests. In addition, a correlation between the storage temperature following welding and the static strength or diffusible hydrogen content of welded parts was found: the higher the storage temperature, the earlier the joint strength increases, and the earlier the diffusible hydrogen decreases.

We aimed to understand the corrosion behavior of Pb-free Cu alloys (Japan Industrial Standards (JIS) CAC411 and CAC901) and the substances (Cu₂S and Bi, respectively), which are in the alloys as particles, in a 3.0 mass％ NaCl aqueous solution. The corrosion behavior of the Pb-free Cu alloys and the substances were compared with those of a Cu alloy (JIS CAC406), which Pb detected as crystallized particles in it, and a Cu alloy (JIS CAC403) without any crystallized substances. Cu₂S specimens were produced by sintering Cu₂S powders. Bi specimens were produced by Bi electro-plating on Cu plates.

The measured corrosion potentials of CAC411, CAC901, and CAC403 were close to that of Sn instead of Cu. The anodic polarization curves of all the Cu alloy specimens showed that the anodic current density increased rapidly at a potential above −0.20 V vs. Ag/AgCl, and the rapid increase in the current density was similar to that of Cu. Therefore, it was concluded that the increase in the current density of the Cu alloys results from the dissolution of Cu in a matrix. Cu₂S was converted into CuS during the anodic reaction. However, the corrosion potential of Cu₂S was higher than those of Cu and CAC411. Therefore, it was concluded that the Cu₂S particles in CAC411 act as cathodic sites and remain stable during the natural corrosion. The corrosion potential of Bi was higher than that of CAC901 and slightly lower than that of Cu. At the potentials below −0.10 V vs. Ag/AgCl, Bi was thought to be covered with a passive Bi₂O₃ film and the passive film was expected to protect Bi from corrosion. Therefore, it was concluded that the Bi particles in CAC901 hardly suffer severe corrosion. The corrosion potential of Pb was lower than those of the Cu and Cu alloys, expect for CAC406. In addition, Pb exhibited a large anodic current density and dissolved actively around the corrosion potential of Cu. Therefore, it was concluded that the Pb particles dissolved preferentially during the corrosion of CAC406 owing to galvanic corrosion. Finally, it was concluded that the Cu₂S and the Bi particles in CAC411 and CAC901, respectively, hardly suffer severe corrosion compared with the Pb particles in CAC406 in chloride-containing aqueous solutions such as sea water.

In this paper, a novel method for recovering platinum using molten FeCl₃-KCl system as “dry aqua regia” is presented. The method consists of the dissolution of platinum by molten FeCl₃-KCl system and the recovery of dissolved platinum by the solvent leaching of frozen FeCl₃-KCl, using the different solubility between platinum compounds and iron compounds for the solvents. Platinum dissolution was conducted in the molten FeCl₃-KCl system at 585-655 K. The maximum dissolution rate of platinum was 0.45 mol･m⁻²･h⁻¹, which is fast enough compared with the hydrometallurgy process using aqua regia or electrochemical dissolution process in ionic liquid. And dissolved platinum recovered as K₂(PtCl₆) by the solvent leaching of frozen FeCl₃-KCl using water or ethanol. This “dry aqua regia” process have a number of advantages, including low energy consumption, easy operation and low toxicity of chemicals compared with pyrometallurgy process and hydrometallurgy process, as recycling process of platinum.

Age-hardening behavior of Fe-Ni-based alloy HR6W was investigated at the temperature range between 973 K and 1073 K. Two-step increase in hardness is detected for the alloy at each temperature; the first increase in hardness results from the precipitation of M₂₃C₆ phase and the second one corresponds to that of Laves phase. The TTP (time-temperature precipitation) diagram for the alloy is established based on the results of hardness measurement and microstructure observation, where the precipitation of Laves phase is slower than that of M₂₃C₆ phase by three orders of magnitude and the nose temperature of Laves phase is above 1073 K. The M₂₃C₆ phase precipitates with plate-like morphology along grain-boundaries at the early stage of aging, followed by the precipitation of Laves phase with granular morphology with increasing aging time. It is found that the M₂₃C₆ and Laves phases are aligned under stress condition, due to their precipitation on the dislocations introduced during creep deformation.