Porous Pd_42.5Cu₃₀Ni_7.5P₂₀ bulk glassy alloy rods with porosities of up to 70% were successfully prepared by high pressure hydrogen of 15 MPa. The melt of Pd_42.5Cu₃₀Ni_7.5P₂₀ alloy kept under high pressure hydrogen absorbs hydrogen and subsequent water quenching of the melt causes the homogeneous dispersion of hydrogen bubbles, which was resulted from the decrease of hydrogen solubility with decrease of pressure. Annealing the hydrogen bubble containing sample at a supercooled liquid state under vacuum, the bubbles are allowed to expand due to the decrease of viscosity of metallic glass matrix. Pores expansion continues until glassy matrix crystallizes or the equilibration among pressure of the pores, pressure of the atmosphere and surface tension is achieved. By utilizing these phenomena, pores up to 80 m in diameters are homogeneously distributed over the whole cross-sectional area of a fully glassy matrix. Under compressive deformation, the porous alloys with porosities exceeding 40% did not show macroscopic fracture in a wide compressive strain range up to 0.6 whereas the non-porous alloy fractures instantly after elastic limit of about 0.02. Porous bulk glassy alloys exhibit higher plateau stress, lower Young′s modulus and higher energy absorption capacity compared with the conventional crystalline metal foams.

View full abstract

Al₃Ni foam was synthesized by a combustion reaction in a hollow steel pipe. Aluminum powder and nickel powder were blended by Al/Ni molar bending ratio of 4.5, and titanium and boron carbide (B₄C) powders were added to increase the heat of reaction. Al₃Ni matrix was synthesized by the reaction between Al and Ni, and TiC and TiB2 particles were formed in the Al₃Ni matrix by the reaction between Ti and B₄C. The blended powder precursor expanded and filled inner space of the pipe during the combustion reaction. The heating rate of the precursor should be lower than a critical level because temperature distribution in the precursor needs to be uniform to avoid inhomogeneous pore formation. At the interface, Al₃Ni foam adhered to the steel pipe without cracks or reaction layer formation. The porosity of the foam in the pipe was around 80%, whereas the porosity of the free foamed specimen was 90%. The pore morphology of the free foamed specimen was equiaxed with vertical/horizontal fillet size ratio of 0.95. The pore morphology became elongated shape along the pipe axis, as the inner diameter of the pipe became smaller. The vertical/horizontal fillet size ratio was 1.61 when inner diameter of the pipe and diameter of the precursor were 30 and 25mm, respectively. The pore size became larger when the combustion reaction was carried out in the steel pipe, compared with the free foamed specimen.

View full abstract

An ultrahigh vacuum stainless-vessel including only solid samples is used as a “Solid Fusion” vessel. When extremely high purity D₂ gas is injected into this stainless-vessel, D₂ gas is penetrated into the solid sample as “D⁺-jet stream” and “Solid Fusion” is generated instantly with ⁴₂He and thermal energy as the reaction products. Consequently, the stainless vessel can act as both a “⁴₂He generator” and a “Thermal Reactor”. As a result, and excellent actual “Solid Fusion” reactor is established for the first time in the world.

View full abstract