On the occurrence of a eutectic-type structure in solidification of Al-Zr alloys

For the first time, experimental evidence is presented for the occurrence of a eutectic reaction in dilute Al-Zr alloys solidified at cooling rates from 0.5 to 5 K/s. Particles which formed at grain boundaries during solidification were confirmed by electron diffraction analysis to be the equilibrium tetragonal DO23 Al3Zr phase. Differential thermal analysis showed a thermal arrest at 658–659 °C, i.e. below the melting point of pure Al, which indicated the presence of a eutectic reaction