In situ EBSD analysis of the deformation mechanisms of a Zn-1wt%Mg alloy manufactured by laser powder bed fusion

The deformation mechanisms of a Zn-1wt.% Mg alloy fabricated by laser powder-bed fusion were investigated by in situ mechanical tests within the scanning electron microscope combined with electron backscatter diffraction. Fully dense samples with a relative density of ∼99.95% were produced using optimized processing parameters. The microstructure consisted of fine equiaxed α-Zn grains (average size ∼2.8 µm) with a weak crystallographic texture, along with a eutectic network of α-Zn + Mg₂Zn₁₁ located primarily at grain boundaries. Plastic deformation was dominated by basal slip, with an increasing contribution of pyramidal II slip at higher strain levels, particularly in grains that had already activated basal slip. Twinning played a negligible role, and grain boundary sliding was suppressed due to the continuous eutectic phase at the grain boundaries. Schmid factor analysis confirmed that both and slip systems followed the Schmid law. Large lattice misorientations developed in the grains, leading to a rapid increase in the density of geometrically necessary dislocations, which triggered dynamic recrystallization at low strains (6.5%). Dynamic recrystallization, driven by progressive lattice rotation and grain fragmentation, hindered the strain hardening. Fracture occurred at low strains (< 10%) and was triggered by the presence of oxide particles that acted as crack initiation sites. These findings provide insights into the deformation behavior of additively manufactured Zn-based alloys and provide valuable guidance for the development of next-generation biodegradable Zn implants with enhanced mechanical performance.