Investigating the Microstructure, Hardness and Tensile Behavior of Magnesium AZ80 Alloy and AZ80/SiC Nanocomposite Manufactured Through Dual Equal Channel Lateral Extrusion (DECLE)

Abstract

In this study, first, AZ80 magnesium alloy and AZ80/SiC nanocomposite were manufactured through a stir casting approach. Then built samples underwent five passes of DECLE process at a constant temperature of 300 °C. Changes in microstructures, hardness, and tensile strength were measured in the annealed alloy and nanocomposites as well as samples with 1, 3, and 5 passes of DECLE to determine the effects of sic. strengthening nanoparticles and number of the DECLE passes. Results show that there is a most significant decrease in grain size due to adding the nanoparticles. The microstructure of the initial AZ80 samples made by large grains and inhomogeneous structure with an average grain size of 60.3 µm. After five DECEL passes for samples with nanoparticles, the structure is turned into fine and homogenous grains with an average size of 4.5 µm. Along with this decreasing trend in the grain size, hardness shows a 20.7% increasing. The results of the uniaxial tensile test show that yield strength and ultimate tensile strength have increased respectively from 74 to 131.8 MPa for initial samples to 113 and 221.9 MPa in nanocomposites. Finally, their values reach to 191.3 and 288.3 MPa after applying five passes of DECLE process. The results indicate that it is possible to significantly improve the microstructure and mechanical properties of the AZ80 magnesium alloy through enriching by nanoparticles. Using severe plastic deformation processes such as DECLE can induce a further decrease in grain size and significant improvement in the mechanical properties without causing changes in the samples’ dimensions.