汽车用钢表面激光熔覆AlCoCrFeNi高熵合金涂层组织及耐磨性研究

Microstructure and Wear Resistance of Laser Cladding AlCoCrFeNi High Entropy Alloy Coating on Automotive Steel Surface

为提升汽车用316不锈钢的耐磨性及硬度,在316不锈钢表面采用激光熔覆技术制备AlCoCrFeNi共晶高熵合金熔覆层。采用金相显微镜(OM)、扫描电镜(SEM)、电子背散射衍射分析技术(EBSD)、显微硬度计、往复式摩擦磨损试验机分别对共晶高熵合金熔覆层的微观组织、相组成、晶体学特征、表面显微硬度、耐磨性及磨损机理进行分析。具体结论如下:AlCoCrFeNi共晶高熵合金涂层的相组成为FCC相和BCC相。EBSD结果表明涂层的晶粒尺寸约为15.34μm,涂层内部具有较高的位错密度。涂层的表面显微硬度为311HV±10.2HV,约为316不锈钢基体的1.7倍。强化机制为固溶强化和位错强化。涂层的摩擦系数约为0.422,比磨损率为4.52×10^(-5)mm^(3)/(N·m),均明显优于316不锈钢基体。磨损机理主要为磨粒磨损,并伴有轻微的黏着磨损。

To enhance the wear resistance and hardness of 316stainless steel in automotive applications,an AlCoCrFeNi eutectic high entropy alloy cladding layer was applied to the steel surface using laser cladding technology.The microstructure,phase composition,crystallographic characteristics,surface microhardness,wear resistance and wear mechanism of the eutectic high entropy alloy coating were analyzed by metallographic microscope(OM),scanning electron microscope(SEM),electron backscatter diffraction(EBSD),microhardness tester and reciprocating friction and wear testing machine.The specific conclusions are as follows:The phase composition of AlCoCrFeNi eutectic high-entropy alloy coating is FCC phase and BCC phase.The results of EBSD show that the grain size of the coating is about 15.34m,and there is a high dislocation density inside the coating.The surface microhardness of the coating is 311±10.2HV,which is about 1.7times that of 316stainless steel matrix.The strengthening mechanism is solid solution strengthening and dislocation strengthening.The friction coefficient of the coating is about 0.422,and the specific wear rate is 4.52×10^(-5)mm^(3)/N·m,which is obviously better than 316stainless steel matrix.The wear mechanism is mainly abrasive wear,accompanied by slight adhesive wear.