Laser forming is a technique for forming a target curved surface by locally bending or shrinking by heating like linear heating process in shipbuilding. In the shipbuilding site, it is empirically known that the final curved surface shape changes due to the influence of thermal history, if the heating order is changed. However, the main cause has not been clarified yet. The authors studied mathematically the relation between the in-plane strain and the curved surface shape in the twisted curved surface forming. Then, it was shown that the difference of in-plane strain distributions caused by the difference in heating order suppressed or promoted twisted deformation. Therefore, if different in-plane strain distributions are formed by changing the heating order with parallel heating lines, bowl-shaped curved surfaces and saddle-shaped curved surfaces can be formed separately. In this paper, we carried out theoretical calculations using a macroscopic dynamic model, simulation by finite element method and experiments of laser forming. And we examined the relationship between heating order and in-plane strain and the possibility of forming bowl and saddle shaped curved surfaces separately. As a result, it was shown by FEM analysis that the peak value of the inherent strain generated by the late heating order is larger than that by early heating order. And we could explain the reason with a macroscopic dynamic model. In addition, by changing the heating order with parallel heating lines, it was possible to form bowl and saddle shaped curved surfaces separately. Finally, we could explain the cause of bowl or saddle shaped curved surface forming using thermal history by changing longitudinal shrinkage distribution.

New biomaterials were fabricated by sintering powders of commercially pure titanium (CP-Ti) and partially-stabilized zirconia (PSZ). The Ti/PSZ composites with different mass fraction of PSZ were consolidated by spark plasma sintering (SPS) at 1173 K and 1373 K. The microstructures of composites were characterized using a scanning electron microscope (SEM), an energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) and an X-ray diffraction (XRD). Vickers hardness tests, reciprocating wear tests, fracture toughness measurements, cell culture tests and electrochemical polarization tests were conducted to discuss their capability for biomaterials as a slide member. The composites with high wear resistance were achieved by sintering at 1373 K with high mass fraction of PSZ; however, fracture toughness showed low value. In contrast, the composites sintered at relatively low temperature of 1173 K with low mass fraction of PSZ showed high wear resistance and fracture toughness. Furthermore, electrochemical characteristics and biocompatibility of composites sintered at 1173 K tended to improve as the mass fraction of PSZ decreased.

This study proposes a casting precursor method for low-cost manufacture of large aluminum foams with complex shapes. We experimentally investigated whether a precursor with low porosity can be used to fabricate an aluminum foam with high porosity. Pure aluminum powder and alumina powder as a thickening agent were added to a molten ADC12 aluminum alloy, and the melt was mixed. Then, titanium hydride powder as a foaming agent was added to the melt, and it was mixed again. The melt was poured into a copper mold and a columnar foamable precursor was obtained. An aluminum foam with maximum porosity of 80% was obtained by heating the precursor (1 mass% pure aluminum powder, 1 mass% alumina powder, 1.5 mass% titanium hydride powder and 96.5 mass% ADC12 aluminum alloy) at 948 K for 7 min. The compressive behavior of the produced aluminum foam was close to that of an ADC12 aluminum foam made in previous research, indicating that the new approach has promise. However, the precursor had about 40% porosity because the titanium hydride decomposed during casting. Thus, we attempted to prevent decomposition of the foaming agent during the casting process. The porosity was increased by increasing the amount of pure aluminum powder added. In contrast, increasing the amount of alumina powder added had almost no effect on porosity because the alumina particles did not disperse fully in the melt due to their low wettability with alumina. The titanium hydride powder was heat treated to prevent its decomposition during the casting process. The heat-treated powder decreased the porosity of the precursor, but the porosity of the aluminum foam also decreased. A low-cost foaming agent with a decomposition temperature higher than that of titanium hydride is needed for low-cost manufacture of aluminum foam by the casting precursor method.

Three Mg single crystalline round-bar specimens with different crystal orientations were subjected to uniaxial tension-compression fatigue tests, and the crystal orientation dependence on fatigue fracture behavior was investigated. The loading direction of AD, BC and EF specimens was [1120], [1100] and [0001] respectively. At stress amplitude(σ_a) over 60 MPa, fatigue life of BC specimen was longest and fatigue life of EF specimen was shortest. When the stress amplitude was 20 MPa, fatigue lives of all specimens were almost the same. Our study suggested that fatigue life in Mg single crystals show high dependence of crystal orientation and stress.

Electrodeposition of Zn-Zr oxide composite was performed from an unagitated sulfate solution containing Zn²⁺, Zr ions and additives such as NO₃^- ions and polyethylene glycol (PEG) at pH 2 and 313 K under galvanostatic conditions, and the effect of additives on the codeposition of Zr oxide and polarization property and micro structure of deposits was investigated. Zr content in deposits obtained at all the current densities increased significantly with addition of 2.0 g・dm^-3 of NaNO₃. Zn-Zr oxide deposited from the solution containing NaNO₃ showed massive structure composed of fine crystals without Zn platelets crystals, and a lot of large cracks occurred between the massive crystals. EDX analysis revealed that Zr codeposited on the massive crystals as fine concavo-convex oxide. The corrosion current density of Zn-Zr oxide deposited from the solution containing NaNO₃ was almost same as that of pure Zn deposits, showing no improvement of corrosion resistance with codeposition of Zr oxide. On the other hand, Zr content in deposits obtained from the solution containing PEG increased significantly with increasing current density above 1000 A・m^-2. With addition of 1000 mg・dm^-3 of PEG, the Zn platelets crystals disappeared, and the deposits were composed of fine mesh-like crystals with preferred orientation {1010}Zn plane, resulting in smooth surface. The cathodic current density for the reduction of dissolved oxygen on the Zn-Zr oxide deposited from the solution containing PEG was smaller than that of pure Zn deposits, as a result, the corrosion current density of Zn-Zr oxide deposits was smaller than that of pure Zn deposits. The increase in Zr content in deposits with NO₃^- ions and PEG is attributed to acceleration of hydrolysis reaction of Zr ions.