Crystal alignment explains why magnesium alloy plates resist ballistic impacts better in one direction

Researchers from Pusan National University, Seoul National University, and Kyungpook National University have discovered that the shape of magnesium alloy plates plays a crucial role in how they resist impacts.

AZ31 Mg alloy, known for its low density and high strength, exhibits anisotropic behavior due to its hexagonal close-packed crystal structure. This means its properties vary depending on the crystallographic orientation. Researchers tested hot-rolled AZ31 Mg alloy plates with a strong basal texture under high-velocity impacts, analyzing energy absorption, penetration behavior, bulging, and fracture morphology.

The study found that impacts along the normal direction absorbed 6.5-6.7% more energy and fractured symmetrically compared to impacts along the rolling direction, which caused localized shear bands and asymmetric fractures. This difference was attributed to distinct deformation mechanisms: normal impacts promoted uniform extension twinning and symmetric deformation, while rolling-direction impacts triggered heterogeneous slip, shear localization, and dynamic recrystallization.

Lead researcher Professor Taekyung Lee suggests that orientation-aware design could significantly enhance the ballistic resistance of magnesium alloy components without increasing weight. By orienting the plate so that impacts arrive in the direction where its texture promotes uniform deformation, engineers can extract free performance from existing materials.

The findings not only provide insights into the deformation mechanisms and macroscopic fracture behavior of textured Mg alloys but also highlight crystallographic texture and component orientation as key design variables for ballistic protection. Further research is needed to assess the approach under more complex, real-world impact conditions.