MICROSTRUCTURES OF AIR ATOMIZED AL-CR POWDERS AND THE MECHANICAL-PROPERTIES OF THE HOT EXTRUDED POWDERS

Rapidly solidified Al-Cr alloys have been prepared by a gas atomizatio n process. Microstructures were examined as a function of cooling rate and chromium content. At a cooling rate of about 10(4) K/s, solute ch romium dissolved in the aluminum matrix up to about 3 at.%. The format ion of icosahedral quasi-crystals during solidification prevented the further extension of the solid solubility. Hot extruded Al-2, 3 and 4 at.% Cr specimens from these powders showed 260 to 360 MPa in ultimate tensile strength at room temperature. It increased with increasing ch romium content.