Microstructural evolution via purity grade of magnesium produced by high pressure torsion

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 823; p. 141735
• Main Authors: Somekawa, Hidetoshi, Yi, Jangho, Singh, Alok, Tsuchiya, Koichi
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 17.08.2021; Elsevier BV
• Subjects: Damping capacity; Deformation mechanisms; Dislocations; Dynamic recrystallization; Grain boundaries; Grain boundary plasticity; Grain boundary sliding; Hardness; Hardness tests; Magnesium; Mechanical properties; Microstructure; Nano-indentation; Nanoindentation; Purity; Severe plastic deformation; Strain rate; Mechanical properties; Grain boundary plasticity; Severe plastic deformation; Magnesium; Damping capacity; Nano-indentation
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2021.141735

The microstructures of pure magnesium produced by high-pressure-torsion (HPT) are influenced by the grade of its purity. Conventional purity magnesium (99.9 mass% purity) readily obtains finer grained structures than those of ultra-high purity magnesium of 99.9999 mass%. This is due to the impurity elements playing a significant role in obstruction of dislocations induced by HPT process; as a result of promoting dynamic recrystallization as compared to that in the ultra-high purity magnesium. Nano-indentation tests reveal that these HPT-ed microstructures affect the mechanical properties (hardness and damping capacity) and the deformation mechanism. Higher damping capacity and larger strain rate dependence on indentation hardness are obtained in the HPT-ed commercial grade magnesium, since grain boundary plasticity, such as grain boundary sliding, contributes to deformation, associated with a high volume fraction of grain boundaries.