Abstract
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.
