Effects of deformation twins on microstructure evolution, mechanical properties and corrosion behaviors in magnesium alloys - A review

Due to lattice reorientation, grain segmentation, induced recrystallization, twins play a very important role in regulating texture, refining grains, improving mechanical properties and corrosion resistance, and has received more extensive attention. Numerous studies have shown that {10-12}<10-11> tensile twins (TTWs) are easily activated in large quantities due to the lower critical resolve shear stresses (CRSS). Introduction of TTWs under uniaxial compression improved the strength, ductility, and formability of magnesium (Mg) alloys. Moreover, TTWs produced by multi-directional impact forging (MDIF) can optimize the microstructure by dividing grains and promoting recrystallization, resulting in significant improvement of mechanical properties. Although {10-11}<10-12> compressive twins (CTWs) and {10-11}-{10-12} double twins (DTWs) can promote dynamic recrystallization (DRX), they are also favorable nucleation sites for cracks. In addition, the type and volume fraction of twins can affect the corrosion resistance, and they also play different roles in the corrosion process of different Mg alloys. Twins have shown great potential for improving structure and properties, but a comprehensive and critical discussion of twins in Mg alloys is still lacking. Therefore, based on previous studies, this article reviews the common types and variants of twins in Mg alloys, influencing factors, and their effects on the microstructure, mechanical properties and corrosion resistance. In addition, some interesting ideas are being proposed for further research.