Liquidus projection of the Al–V–Zr system

Phase equilibria knowledge on the Al–V–Zr system has an important role for designing low-density Al-containing refractory multi-principal element alloys. In order to contribute to the literature data related to this system, the liquidus projection of the Al–V–Zr ternary system was experimentally investigated in this work by microstructural characterization of as-cast alloys. Sixty alloys were produced in an arc furnace, the microstructures of the as-cast alloys were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) for the determination of the chemical composition of the phases and microconstituents as well as X-ray diffractometry (XRD). The liquidus projection of the Al–V–Zr system is presented in this work for the first time in the literature. Through microstructural analysis and thermodynamic extrapolation, three Class I, eleven Class II and one Class III ternary invariant reactions are proposed. The results showed that the ternary compound Zr_0.9V_0.4Al_2.7 is formed from the liquid through the following reaction: L + ZrAl₂ → Zr_0.9V_0.4Al_2.7. The limits of the 12 primary solidification regions are established and the nature of the monovariant and ternary invariant reactions are determined. The ZrAl₂ primary solidification region significantly extends into the liquidus projection, participating in most reactions involving the other phases in equilibrium with the liquid.