Effect of alloying elements and degassing pressure on the structure and mechanical properties of rapidly solidified Al-20Si-5Fe-2X (X = Cr, Zr, or Ni) alloys

Rapidly solidified Al-20Si-5Fe-2X (X = Cr, Zr, or Ni) alloys produced by ga s atomization were degassed under different vacuum levels before consolidat ing them by hot extrusion. The microstructure and mechanical properties of the as-solidified and extruded alloys were evaluated. It was shown that the addition of a quaternary element resulted in the formation of very fine pa rticles that contributed to the improved mechanical properties of the alloy s, especially at elevated temperatures. Of these additions, nickel was foun d to be the most effective in increasing the UTS of the alloy both at room and elevated temperatures. Degassing the rapidly solidified powders under b etter vacuum improved the properties further. (C) 2000 Elsevier Science S.A . All rights reserved.