Disks of an extruded magnesium WE43 alloy are processed by high-pressure torsion (HPT) and the evolutions of microstructure and mechanical properties are investigated in detail. Excellent grain refinement is achieved by HPT processing with a reduction in grain size from an initial value of ?12??m to a final value of ?200–300?nm after 10 turns. The microhardness increases significantly with HPT processing but low hardness values are recorded at the centers of the disks. The tensile strength initially increases and then decreases while the elongation decreases. Observations of the fracture surfaces reveal a corresponding transition of the fracture mode from ductile to brittle.
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