Investigating the Synergic Effects of WS2 and ECAP on Degradation Behavior of AZ91 Magnesium Alloy

Abstract

In this research, WS2/AZ91 metal matrix composites were manufactured using the stir casting method. The composites were severely deformed using equal channel angular pressing (ECAP). The degradation behavior of severely deformed and as-cast samples was investigated using the three-electrode system in a 3.5 wt% NaCl solution. The corrosion products and surface morphology of the corroded surfaces were investigated using an x-ray diffractometer and scanning electron microscopy. The results revealed that as-cast monolithic AZ91 exhibited the highest corrosion potential of (−1.553 mV) and a minimum degradation rate (4.099 m·a−1). The reduction ion grain size after severe plastic deformation increased the degradability of WS2/AZ91 composites. Severe plastic deformation reduced the grain size, which led to an increase in the corrosion rate. The synergic effects of (tungsten disulfide) WS2 and ECAP increased the degradation rate to (4.59 m·a−1) in two-pass 1 wt% WS2/AZ91. The increase in WS2 contents decreased the degradation rate (4.512 m·a−1) in homogenized 1 wt% WS2/AZ91 composites. The degradability of AZ91 increased in all conditions under the synergic effects of WS2 and severe plastic deformation. Magnesium and magnesium hydroxide were observed as corrosion products. The maximum surface roughness in two-pass 1 wt% WS2/AZ91 indicated the highest material removed by corrosion from the surface of the composites.