Effects of Y addition on microstructure and properties of Al-Zr alloys

Microstructure and properties of Al-0.30Zr and Al-0.30Zr-0.08Y (mass fraction, %) alloys were investigated by electrical conductivity measurements, microhardness tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Micron-sized primary Al3Y phases form within grains and at grain boundaries simultaneously as product of eutectic reaction in as-cast Al-Zr-Y alloys. The addition of Y obviously accelerates the precipitation kinetics of Al3Zr (L12) in Al-Zr-Y alloys. The Al-Zr-Y alloys exhibit greater electrical conductivity during aging due to formation of increased volume fractions of Al3(Zr,Y) precipitates. In ternary Al-Zr-Y alloys, spheroidal L12-structured Al3(Zr,Y) precipitates with increased number density and smaller mean radius were observed. The Al-0.30Zr-0.08Y alloys show improved recrystallization resistance compared with Al-0.30Zr alloys