Wrought magnesium (Mg) and Mg alloys have emerged as competitive alternatives for structural components in transportation, aerospace, and medical industries due to their low density, high specific stiffness, and good biocompatibility. Designing high-performance wrought Mg alloys requires understanding the relationship between microstructure and deformation mechanisms (slip and twinning), especially at room temperature, which has not been fully established.

This thesis studies experimentally the deformation mechanisms of various wrought Mg alloys with different microstructures at ambient temperature, using state-of-the-art techniques such as electron backscatter diffraction, transmission electron microscopy, slip trace analysis, slip trace – modified lattice rotation analysis, grain reference orientation deviation, as well as machine learning.

Chapter 3 explores the deformation mechanisms of an as-extruded Mg-6.5Zn alloy with dual texture and limited yield asymmetry under tension and compression. Compressive deformation in grains with standard prismatic texture is accommodated by <a> basal slip and extension twinning, while tensile deformation promotes <a> basal and non-basal slips, leading to the typical yield asymmetry. Rotated grains, however, exhibit stronger yield asymmetry, with tensile deformation absorbed by <a> basal slip and extension twinning, and compression relying on <a> basal slip and compression twinning. Moreover, activation of <a> non-basal slips can suppress compression twinning transforming into double twinning.

Chapter 4 studies the influence of prismatic precipitates on the deformation mechanisms of Mg-4.5Zn alloys with a strong prismatic texture during tensile deformation. In samples without precipitates, 92% of grains with slip traces are planar, primarily involving <a> basal slip and <c + a> II pyramidal slip. In samples with precipitates, 76% of grains with slip traces are non-planar, with <a> prismatic slip being most active, followed by <c + a> II pyramidal slip. Precipitation-induced hardening of <a> basal slip favored cross-slip to the prismatic plane, progressing deformation via <a> prismatic slip dislocations parallel to precipitates.

Chapter 5 examines the deformation of a Mg-1Al alloy with a strong prismatic texture, focusing on the nucleation and growth of anomalous extension twins during tension. These twins nucleated at the onset of plastic deformation near grain boundary triple junctions due severe strain incompatibility between neighbor grains as a result of different <a> basal slip-induced lattice rotations. Anomalous twins grew with applied strain due to continuous activation of <a> basal slip in adjacent grains, increasing strain incompatibility.

Chapter 6 investigates the influence of microstructure on extension twinning behavior using a large grain dataset (> 3000 grains × 28 features) and machine learning. Twin nucleation was favored in larger grains and grains with high twinning Schmid factors, but twins also formed in grains with very low or negative Schmid factors if they had at least one smaller, or more rigid, neighbor grain. Twinning in small grains with high twinning Schmid factors was favored if they had low basal slip Schmid factors and at least one neighbor with high basal slip Schmid factors that deformed easily.

All these results reveal the complex deformation mechanisms of wrought Mg alloys with different microstructures and help to advance in the microstructural design of high-performance Mg alloys.