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 gas atomization were degassed under different vacuum levels before consolidating 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 particles that contributed to the improved mechanical properties of the alloys, especially at elevated temperatures. Of these additions, nickel was found to be the most effective in increasing the UTS of the alloy both at room and elevated temperatures. Degassing the rapidly solidified powders under better vacuum improved the properties further.