Papers by Author: Kanryu Inoue

Abstract: CuAlNi shape memory alloy with Cu-13.5Al-4.5Ni(wt%) composition was prepared by cross-rolling method and the aging effect, phase transformation characteristics, microstructural variation were investigated. Transformation temperature was greatly increased in aged specimens at 250°C. Transformation temperature was not changed after the second reversed transformation, and Ms point was same in most specimens with third reversed transformation cycle. The variation of Ms point was not seen with aging at 100°C, but it was decreased with aging at 250°C. Transformation temperatures appear to be constant, to an measurable extent, in specimens prepared by both hotrolling and cross-rolling at 900°C. Plate shaped-specimen with the thickness of about 1mm was prepared by cross-rolling treatment at 350°C. The transformation temperatures did not change after the second transformation-reverse transformation cycling, and specially transformation start temperature was the same in most specimens experiencing third thermal cycle and thereafter. Undesirable tweed-like structure was observed in 250°C-aged specimen after a cross-rolling at 350°C. On aging the specimen prepared by cross-rolling, G.P zone was formed easier than that of γ2 phase. This phase was transformed to plate-like θ phase during aging.

Abstract: The purpose of this work is to quantitatively clarify the shape memory behavior of Fe-Pd films containing ~30at%Pd by thermal cycling testing under various constant stresses. Fe-Pd films (4 $m thick) were deposited onto Si wafers with thermally formed 1$m-thick SiO2 layer using a dual-source dc magnetron sputtering apparatus. The deposited films were all annealed at 900°C for 60 min followed by iced water quenching. Perfect shape recovery was observed for Fe-30.0at%Pd film when the applied stress was lower than 300 MPa. The maximum recoverable strain was ~0.6%. Fe-29.2at%Pd film, on the other hand, showed unrecovered strain after thermal cycling even if the applied stress was 40 MPa. XRD measurements of the Fe-29.2at% Pd film before and after thermal cycling revealed irreversible fcc-bct martensitic transformation that occurred during cooling process at a temperature around -80°C. The critical stress of Fe-Pd films, at which plastic deformation commences to occur, is higher for films with 30 at% Pd than for films with 29.2 at% Pd, which is practically advantageous. The Ms temperature of these films is lower than room temperature when no bias stress is applied, while it becomes higher than room temperature when appropriate bias stress is applied, obeying Clapeyron-Clausius law.

Abstract: Boron-fiber-reinforced Al-matrix composite was fabricated by a pulsed current hot pressing (PCHP) process at a pressure of 32MPa for 600s. It was found that the boron fiber and the Al-matrix were well bonded when the PCHP process was performed at a holding temperature of 773K. No interfacial reaction layer was observed along the interface between the boron fiber and the matrix when PCHP was done at 773K for 600s. Tensile deformation carried out at room temperature for the composite showed that the tensile yield stress increased with increasing volume fraction of the boron fiber in the composite. The composite with 17.2 vol.% of boron fiber presented a tensile yield stress of 600MPa. This value was about 90% the yield stress estimated by a force equilibrium equation of a composite taking into account the direction of fiber axis.

Abstract: Small-angle scattering measurements utilizing anomalous dispersion effect just below the Zr and Ni K edge have been made for welded Zr-based amorphous materials. The measurements were carried out at a bending magnet beam-line 40B of SPring8. A small and parallel X-ray beam generated at the third generation synchrotron is suitable for nanostructure mapping of heterogeneous materials, whose structure varies with less than a millimeter scale. The remelted and heat-affected zones were examined for electron-beam welded Zr-Ni-Cu-Al alloys. Merits and the characteristics, as well as its present limitations of scanning small-angle scattering with a use of anomalous dispersion effect is discussed as a tool to examine microstructure in the spatially inhomogeneous materials in macroscopic scale as well as microscopic scale.