激光熔覆FeCrNiCoMoCuBSi高熵合金涂层的腐蚀磨损性能

Tribocorrosion Behavior of Laser Cladding FeCrNiCoMoCuBSi High Entropy Alloy Coating

利用激光熔覆技术在316L不锈钢表面制备了FeCrNiCoMoCuBSi高熵合金涂层,分析了其组织结构、硬度、摩擦磨损、电化学腐蚀和腐蚀磨损性能。结果表明,熔覆层成型良好,表面无裂纹、气孔等缺陷。熔覆层主要由fcc固溶体相和(Fe,Cr)2B相组成,微观组织以“柳条状”树枝晶为主,结合区为平面晶,与基体呈良好的冶金结合。熔覆层的平均硬度HV0.2为6860 MPa,约为基材的3.5倍。熔覆层在不同载荷下的摩擦系数均低于基材,磨损量小于基材,表现出明显优于基材的耐磨性。在3.5%(质量分数,下同)NaCl溶液中,熔覆层自腐蚀电流密度为4.74×10^(-8)A·cm^(-2),低于基材2个数量级,耐蚀性优异。在摩擦载荷与腐蚀耦合作用下,熔覆层开路电位发生负偏移,腐蚀倾向增大。随摩擦载荷增大,自腐蚀电位负移,自腐蚀电流密度增大,摩擦促进腐蚀作用增大。

The FeCrNiCoMoCuBSi high-entropy alloy coating was prepared on the surface of 316L stainless by laser cladding technology.The microstructure,hardness,wear,electrochemical and tribocorrosion properties of the coatings were studied.The results show that the cladded coating is well formed with no defects such as cracks and pores on the surface.The cladded coating is composed of fcc solid solution phase and(Fe,Cr)2B intermetallic compound,the microstructure is dominated by“wicker-like”dendrites,and the bonding area is planar crystals,which has a good metallurgical bond with the 316L stainless.The average hardness(HV0.2)of the coating is 6860 MPa,which is about 3.5 times that of the substrate.The cladded coating shows significantly better wear resistance than the substrate under different loads with the lower friction coefficient and the less wear amount.In 3.5wt%NaCl solution,the self-corrosion current density of the coating is 4.74×10^(-8) A·cm^(-2),which is two orders of magnitude lower than that of the substrate,showing excellent corrosion resistance.Under the coupling effect of friction load and corrosion,the open circuit potential of the coating shifts negatively and the corrosion tendency increases.With the increase of friction load,the free-corrosion potential moves negatively,the free-corrosion current density increases,and the effect of friction promoting corrosion increases.