Effect of Sc and Zr addition on the structures and mechanical properties of rapidly solidified Al–transition metal alloys

Abstract

Effect of combined addition of Sc and Zr on structure and mechanical properties was investigated, in rapidly solidified Al–8%Fe, Al–4%Fe–4%Ni, Al–8%Mn and Al–8%Mn–2%Cr alloys containing combination of 0.2% Sc and 0.2% Zr. Rapid solidification was performed by gas atomizing the alloy melt and subsequent splat-quenching on a rotating water-cooled copper roll under an argon atmosphere. The rapidly solidified flakes were consolidated to the P/M materials by cold pressing, vacuum degassing and hot extrusion. TEM observation revealed that the matrix sub grain size was slightly smaller for the rapidly solidified P/M materials with Sc + Zr addition than for those without addition. Hardness of the P/M materials with Sc + Zr addition was higher than those without addition except for Al–8Mn–2Cr alloy. Tensile strength at room temperature was also higher for the materials with Sc + Zr addition except for Al–8Mn–2Cr alloy. However, increments in tensile strength due to Sc + Zr addition decreased with rising test temperature. Higher strength attained by Sc + Zr addition is considered mainly due to precipitation of Al₃(Sc, Zr).