In the sandwich constructions about one element of the honeycomb core, we researched on the buffer characteristics theoretically and experimentally and we gained the following results.
(1) The maximum compressive load converges on a constant value with the increase of the impact speed.
(2) 1/WV with respect to the momentum, is proportional to the point of some impact speed, and further that speed is constant about any form of the honeycomb core.
(3) The mean crushing load is no relation to the impact velocity and the mass weight, and becomes nearly constant.
(4) The dynamic maximum compressive load is about 1.7 times of the static value.

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Attempts have been made to clarify the pattern of pitting distribution on Al-Fe alloys in deaerated 0.1 M NaCl solution. Anodic dissolution (10μA/cm²) has been employed to get the pitting patterns. Using the method of "interaction potentials of spatial point patterns through the maximum likelihood procedure", specimen No. F1 (0.32 wt%Fe) and specimen No. F2 (0.59 wt%Fe) show the attractive or singular type distribution pattern, however specimen No. F3 (1.04 wt%Fe) and specimen No. F4 (1.45 wt%Fe) show the repulsive or regular type distribution pattern.

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Both squeeze and gravity castings of ADC 12 aluminum alloy were friction-welded, using a brake type welding machine. Mechanical properties and microstructures of the friction welded joints were investigated. The cast structures are pressed forward to outside along the flux of burr in the heat affected zone by axial pressure, while they disappear near the weld interface. The width of the heat affected zone of the castings is narrower than that of the wrought aluminum alloys. Hardness increases much in the weld interface, but it decreases a little in heat affected zone comparison with that of parent material. The welded joints have the same tensile strength and elongation as those of parent materials. Fracture occurs in the heat affected zone or in the parent material at a friction time of 2 to 3 sec., whiel it occurs at or near the weld interface at other friction time. The weld interface has a higher impact value than the parent material, but the place at 1 mm far from the weld interface has the same value as the latter. The fatigue strength of the welded joints of squeese castings is higher than that of parent materials. On the other hand, that of the gravity castings is slightly lower.

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The temperature rise and the extrusion pressure during extrusion operation are calculated by dividing billet, die, container and dummy block in to small elements. Heat transfer is calculated by the difference equation method. Heat generated are assumed as mechanical energy change to heat energy. Yield strength of metal in each elements of the billet are treated as the function of strain rate and temperature. As to movement of metal in the billet, two opposit assumptions are set up and calculated, expecting the solution will be between of the two. Temperature distribution in the billet calculated by the two methods are quite different, but extrusion pressure are quite similar.

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The possibility of rationalization of heat treatment by using preferable heat treating condition and alloy composition was studied on Al-Si-Mg casting alloys. Al-4.5%Si-0.5%Mg-0.15%Ti-0.10%Sb alloy solution treated at 540°C for 1h has ultimate strength identical to and elongation greater than those of Al-7%Si-0.3%Mg-O.15%Ti-0.10%Sb alloy solution treated at 550°C for 6h because of eutectic Si crystals further refined and homogeneously dispersed. Al-7.0%Si-0.35%Mg-0.15%Ti-0.10%Sb alloy is less susceptible to pouring temperature than JIS casting alloy AC4C.

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The measurement of the solid-liquid interface positions during the unidirectional solidification of aluminum and aluminum-copper alloys was tried using ultrasonic wave and acoustic emission on solidification. For pure aluminum and aluminum-copper eutectic alloy, each of which had planner: interfaces in unidirectional solidification, it was possible to determine the interface positions by measuring the time delay of the reflected sound wave from the interface to a certain surface of specimens. For aluminum-4.5% copper alloy, no reflection of sound wave from interface region could be observed, thus the determination of interface position was impossible. Acoustic emission was clearly observed when the solidification front reached to the wave guides inserted into the specimen. With this acoustic emission, interface positions could be easily determined in spite of the variations of the interface morphology of tested alloys.

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As the first step of production of P/M aluminum materials, an experimental apparatus has been made for continuous production of splat quenched aluminum alloy flakes. The apparatus, by which aluminum alloy melt is atomized into small droplets and subsequently splat quenched on a rotating water-cooled copper drum, is capable of producing flakes at a rate of 5 g/s. Splat quenched flakes of Al-218 wt%Fe, Al-511 wt%Mn and Al-818 wt%Ni alloys were produced and their properties were examined.
A typical flake is approximately 10 mm in diameter, and its thickness is about 30 μm at the center and increases near the edge. From the measurement of eutectic interlamellar spacing of Al-33 wt%Cu alloy flakes, the cooling rate was estimated as 3×10⁵°C/s at the center. The formation of primary intermetallic compounds is suppressed in splat quenched flakes of all the alloys tested. The structures of splat quenched flakes of Al-Fe and Al-Ni alloys are fine cellular and rod or lamellar eutectic, respectively. A supersatulated solid solution is formed in Al-Mn alloys, which decomposes upon heating at above 350°C. The hardness of as splat quenched flakes, which is higher for the higher content of alloying elements, is thermally stable up to 350°C in Al-Fe and Al-Mn alloys.

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The morphology of tensile fracture of Al-6 wt%Zn-1.9 wt%Mg-(03 wt%) Cu alloys subjected to isothermal aging at 125°C were investigated in relation to their tensile properties, precipitate and deformed structures. After prolonged aging, copper-bearing alloys exhibited higher strength and higher elongation compared with the ternary alloy. The improved ductility of copper-bearing alloys was due to the suppression of intergranular fracture. Localized intragranular deformation and preferred deformation within PFZ were similarly observed even in copper-bearing alloys. Intergranular fracture surfaces were commonly composed of numerous dimples which were probably formed by the decohesion of the interface between grain boundary precipitates and the matrix. Copper addition little varied the width of PFZ but markedly refined grain boundary precipitates. The refinement of grain boundary precipitates was considered to be responsible for the suppression of intergranular fracture.

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