Mechanical Properties of ZK60 Magnesium Alloy Processed by High-Pressure Torsion

Abstract

Severe plastic deformation routes such as high-pressure torsion (HPT) are capable of producing ultrafine grain sizes in various alloys, specifically in magnesium alloys which exhibit poor ductility due to their hexagonal close-packed (hcp) crystal structure. HPT was performed on ZK60 magnesium alloy samples at room temperature under a pressure of 2.0 GPa up to 5 turns. The Vickers microhardness values were obtained from the centre to the edge of the disc samples and they show a slight hardness gradient with values which are lower at the centre of the samples and higher towards the edge. By increasing the numbers of turns in HPT, the hardness values increase to a saturation level and the gradient is removed. Tensile tests were performed at high temperatures and the results reveal a significant increase in elongation to failure as the numbers of turns in HPT increases. It is shown that microstructural analysis is in agreement with the results obtained from mechanical testing.