Abstract:

This work focuses on the hot corrosion performances of CrCoNi medium entropy alloy （MEA） prepared by laser melting deposition （LMD）， and solves the problem that affecting laws of temperature on the hot corrosion kinetics， corrosion morphology and product of MEA. The following results are obtained： the phase of the formed alloy is FCC phase， and the sample contains a small amount of pores and cracks. The microstructure is a mixed dendritic substructure of equiaxed cell and column dendrites. The hot corrosion rates k_p at three temperatures of 700，900 and 1 100 ℃ are 3.920 37×10⁴， 0.002 36， and 0.005 49 mg²/（cm⁴·h）， respectively. The hot corrosion rate increases with the increase of temperature at three different temperatures， and the hot corrosion kinetics curve basically follows the parabolic law； The corrosion layer products are Cr₂O₃ and a small amount of NiCr₂O₄ and CoCr₂O₄ spinel phases. Under the combined action of volatile chlorine gas and thermal stress， the corrosion layer will undergo damage and peeling. The research results have theoretical value for promoting the application of LMD-prepared MEA in high-temperature structural components.

Key words: mechanical engineering, laser melting deposition, CrCoNi medium entropy alloy, hot corrosion, corrosion kinetics