Amorphous metallic foam

The bulk glass forming alloy Pd43Ni10Cu27P20 is processed into a low-density amorphous metallic foam. Pd43Ni10Cu27P20 is mixed with hydrated B2O3, which releases gas at elevated temperature and/or low pressure. Very homogeneous foams are achieved due to the high viscosity of the alloy even at its liquidus temperature. By processing at the liquidus temperature and decreasing the pressure to 10(-2) mbar, well-distributed bubbles expand to foam the material. Foam densities as low as 1.4x10(3) kg/m(3) were obtained, corresponding to a bubble volume fraction of 84%. The bubble diameter ranges between 2x10(-4) and 1x10(-3) m. Thermal analysis by differential scanning calorimetry confirms the amorphous nature of the foam. Furthermore, it reveals that the foam's thermal stability is comparable to the bulk material. (C) 2003 American Institute of Physics.