Dynamic loading behaviour of CrMnFeCoNi cold spray coatings

FeCoCrNiMn high entropy alloy powders were employed to produce coatings on carbon steel through high pressure cold spray. The microstructure of the sprayed coatings, characterized through optical and electron microscopy as well as through X-ray diffraction revealed a low porosity compact aspect of the cross sections as well as the retention of the body centered cubic crystallographic structure after particles splat. A high flattening ratio of the particles, measured by the scanning electron microscope observations, indicated an excellent adhesion of the coating to the substrate. Residual stresses of the coatings were measured through X-ray diffraction at different levels of the coating thickness; the hardness profile was revealed through nanoindentation. The cyclic behavior of the coatings was evaluated through 3 point bending tests. Cyclic tests were performed by increasing the maximum stroke from 0.3 to 2.4 mm with steps of 0.3 mm each 200 bending cycles. Other 3-point bending tests were conducted at fixed maximum stroke at the same deformation levels indicated for the previous test. Each 100 cycles the test is stopped and the coating surface is observed in order to monitor the superficial fracture behavior. The fracture surface of the coatings after rupture were observed through scanning electron microscopy in order to describe the rupture features related to the different loading conditions imposed to the coatings.