Microstructure and mechanical properties of EZ30Z magnesium alloy block produced by arc additive manufacturing

• CMT-WAAM technology can successfully prepare EZ30Z magnesium alloys with uniform microstructure and excellent properties. • The alloy has an equiaxed structure with distinct fine-grained and coarse-grained regions. • The mechanical properties exhibit some anisotropy, but are generally superior to those of the as-cast alloy. • The strengthening mechanisms mainly include grain refinement, precipitation strengthening, and heterogeneous nucleation. In this research, an EZ30Z magnesium alloy block was fabricated using Cold Metal Transfer-Wire Arc Additive Manufacturing (CMT-WAAM) to clarify the relationships among thermal cycling, microstructural evolution, and anisotropic mechanical behavior. Magnesium alloy components generally exhibit an equiaxed crystal morphology, with equiaxed grain regions widely distributed in different locations, while remelted fine grain regions are mainly distributed between different deposition passes. The deposited alloys demonstrate anisotropic mechanical properties: the mechanical properties of tensile specimens from different sampling directions differ, but are all far superior to those of the as-cast alloys. The superior performance was considered resulting from multiple factors, including grain refinement, dispersion strengthening, and heterogeneous nucleation caused by pre-existing rare earth and zirconium particles. This work demonstrates that CMT-WAAM enables the production of structurally homogeneous, precipitation-strengthened Mg alloys with mechanical properties surpassing those of conventionally cast counterparts, underscoring its potential for lightweight structural applications.