Microstructure and tribological properties of laser cladded FeCrCoMn high entropy alloy coatings
The FeCrCoMn high entropy alloy coatings were prepared on 45 steel substrates using laser cladding technology by designing a triangular powder preforms,and the effects of the solidification process on the structure and tribological properties of the coating were investigated.It is found that under the same solidification conditions,the increase in the width of the precet layer w reduces the solidification cooling rate,which results in the dissolving precipitation of the σ phase in the bi-phase FCC+HCP solid solution,and the microstructure evolves gradually from equiaxed crystals to columnar crystals and dendritic crystals,with a gradual increase in grain size.The tribological investigation shows that with the increase in the width of the pre-positioned layer,the wear is gradually serious due to the decrease of coating hardness and coarsening of the structure.However,when the width of the pre-positioned layer is 20 mm,the precipitated σ phase with higher hardness plays an anti-wear role to a certain extent,the friction coefficient and the wear rate are reduced,and the wear mechanism is dominated by abrasive wear.The results show that the solidification process is the key factors that cannot be ignored in laser cladding technology which will dominate the structure and properties of FeCrCoMn high entropy alloy coatings.
high entropy alloy coatingsolidification processlaser claddingmicrostructuretribological perform-ance
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