This study evaluates the corrosion and erosion-corrosion behaviour of two complex concentrated alloys (CCAs), CoCrFeNiMo0.85 and Al0.5CoCrFeNi, deposited by Laser Metal Deposition (LMD) onto a stainless steel substrate. The performances of the CCAs were compared to wrought stainless steel (UNS S30403) and carbon steel (P265GH). Erosion-corrosion testing was conducted using a submerged impingement jet test rig utilising a slurry comprising angular silica sand in an aqueous solution of 3.5%NaCl, adjusted to a pH of 4, impinging at 90°. Electrochemical monitoring was also undertaken in quiescent, flowing and solid-liquid conditions. The microhardness of CoCrFeNiMo0.85 was observed to be significantly greater compared to Al0.5CoCeFeNi due to the presence of intermetallic phases (identified by XRD) in the former. Although the CoCrFeNiMo0.85 CCA generally demonstrated superior durability than the CoCrFeNiMo0.85 variant, the relative performances of the investigated materials were observed to be dependent upon the hydrodynamic conditions. An important factor was the complex influence of corrosion on the overall erosion corrosion process. Indeed, when cathodic protection was applied, less distinct differences between the investigated alloys were evident in terms of the resulting pure mechanical damage. Post-test microscopy using SEM demonstrated that both CCAs experienced similar mechanical degradation mechanisms – sliding abrasion in low angle conditions and plastic deformation and micro-cracking in high angle conditions.
- compositionally complex alloys
- laser metal deposition