Investigation of primary Al-3(Sc,Zr) particles in Al-Sc-Zr alloys

This paper studied the primary Al-3(Sc,Zr) particles formed during solidification in three Al-Sc-Zr alloys with various Zr contents. It has been shown that the primary Al-3(Sc,Zr) particles formed during solidification since the Sc and Zr concentrations are above the solid solubility limit in Al matrix. Scanning electron microscopy line scanning results indicated that the distributions of Sc, Zr and Al atoms in the primary Al-3(Sc,Zr) particles differ a lot from those in the secondary Al-3(Sc,Zr) particles formed during annealing. In the primary Al-3(Sc,Zr) particles, both Sc and Zr contents are found from rim to the centre of the particles, with an increasing trend from the rim to the centre, while the Al content drops sharply on the rim of the particle and slightly from the rim to the centre.