Two Ni-AlSi12 coatings were prepared using mechanical alloying (MA) and mechanical alloying followed by laser cladding (LC), respectively. Phase composition and microstructure variations caused by powder weight ratio and laser-specific energy were thoroughly analyzed in this study. Mechanical properties and oxidation behavior are markedly improved by subsequent laser cladding. The MA-LC coating, characterized by high densification and crack-free properties, presents a homogeneous microstructure with refined features. Microhardness testing reveals a marked superiority of the MA-LC coating over the conventional MA coating. The nano-hardness of MA-LC coating is 9.79 GPa, exhibiting that it is 6.84 times the nano-hardness of the MA sample. Owing to metallurgical bonding, the MA-LC coating possesses excellent scratch bonding performance. The MA-LC coating shows favorable oxidation behavior, due to the following three reasons: Firstly, oxygen diffusion can be effectively blocked by the compact Al₂O₃ oxide layer developed on the MA-LC coating surface, which reduces the oxidation velocity. Secondly, the coating’s mean grain dimensions demonstrate an increasing tendency after oxidation, which reduces the grain boundary serving as the oxygen diffusion channel. This enhancement significantly improves the coating’s oxidation resistance. Thirdly, analysis of the coating’s respective kernel average misorientation (KAM) map revealed a significant release of internal stress following 100 h oxidation, which can improve the coating’s resistance to spallation.

This work systematically investigates the Zn-content-dependent phase evolution (1–12 at.%) and its correlation with mechanical properties in as-cast Mg–2Y–xZn alloys. A sequential phase transformation is observed with the Zn content increasing: the microstructure evolves from X-phase dominance (1–2 at.% Zn) through W-phase formation (3–6 at.% Zn) to I-phase emergence (12 at.% Zn). Optimal mechanical performance is attained in the 2 at.% Zn-containing alloy, with measured tensile properties reaching 239 MPa UTS and 130 MPa YS, while maintaining an elongation of 12.62% prior to its gradual decline at higher Zn concentrations. Crystallographic analysis shows that the most significant strengthening effect of the X-phase originates from its coherent orientation relationship with the α-Mg matrix and the development of deformation-induced kink bands. Meanwhile, fine W-phase particles embedded within the X-phase further enhance alloy performance by suppressing X-phase deformation, revealing pronounced synergistic strengthening between the two phases. Notably, although both the I-phase and W-phase act as crack initiation sites during deformation, their coexistence triggers a competitive fracture mechanism: the I-phase preferentially fractures to preserve the structural integrity of the W-phase, effectively mitigating crack propagation. These dynamic interactions of second phases during plastic deformation—synergistic strengthening and competitive fracture—provide a novel strategy and insights for designing high-performance Mg–RE–Zn alloys.