Microstructure characterization of a directionally solidified Mg-12wt.%Zn alloy: Equiaxed dendrites, eutectic mixture and type/ morphology of intermetallics

Highlights: •A dendritic $\alpha -Mg$ matrix and a eutectic $\alpha -Mg$/$M{g}_{21}Z{n}_{25}$ typify the microstructure of the Mg-12 wt.%Zn alloy. •The eutectic mixture has two morphologies: lamellae and rods, the latter increasing with decreasing cooling rates. •Eutectic spacing (λ) and the growth rate (V) are related by the Jackson-Hunt equation: λ²V = constant. •Non-equilibrium MgZn₂ and Mg₄Zn₇ nanoparticles are distributed throughout the $\alpha -Mg$ matrix.