Microstructure of die cast and thixocast ZAEX10430 (Mg–10Zn–4Al–3Ce–0.3Ca) alloy

The microstructure and phase composition of die cast and thixocast ZAEX10430 (Mg–10Zn–4Al–3Ce–0.3Ca) alloy were studied. Two intermetallic phases were identified in both the die cast and the thixocast specimens: the τ-phase doped with calcium (Mg,Ca)32(Al,Zn)49 (or τ′-phase) and the (Al,Zn)xCe isomorphous phase with Al2CeZn2 and Al4Ce. In all of the specimens, the τ′-phase crystallized mostly as fine elongated particles and within a lamellar constituent. Needle-like (Al,Zn)xCe phase particles were visible in the die cast specimens, whereas coarse particles of various cross-sectional shapes (polygonal, elliptical, rod-like, etc.) were observed in the thixocast specimens. The difference in morphology of the intermetallic (Al,Zn)xCe particles in the matrix and the presence of large primary α-Mg grains in the thixocast specimens was used to explain the different creep behavior of die cast and thixocast ZAEX10430 alloy reported previously.

► Specimens of Mg–10Zn–4Al–3Ce–0.3Ca alloy were die cast and thixocast.
► The microstructure of this creep resistant alloy was characterized.
► Composition and morphology of Al–Ce–Zn and Mg–Zn–Al–Ca particles were compared.
► Al–Zn–Ce particles were isomorphous to Al4Ce with (Al,Zn)xCe (2.5 < x < 5.2).
► Mg–Al–Zn–Ca particles were isomorphous to τ′-(Mg,Ca)32(Al,Zn)49.