激光重熔高速电弧喷涂FeNiCrAl涂层的组织与断裂韧性

Microstructure and Fracture Toughness of Laser Remelting Treatment on FeNiCrAl Coating by High-Velocity Arc Spraying

采用激光技术对高速电弧喷涂Fe Ni Cr Al涂层进行重熔处理.分析了重熔前后涂层的组织结构、物相成分、显微硬度与断裂韧性.结果表明:重熔后,喷涂层片层状堆叠结构与孔隙得到消除,组织结构变得均匀、致密,涂层与基体由机械结合变为冶金结合.喷涂层物相主要有α-Fe及金属间化合物AlFe_3,AlFe和Al_(0.4)Fe_(0.6),重熔后,生成了新相Fe-Cr,[Fe,Ni]固溶体和碳化物Ni Cx.重熔后涂层的平均显微硬度为7.7 9GPa,约为基体硬度(2.5 GPa)的3倍,约为喷涂层硬度(6.0 GPa)的1.3倍.载荷为4.9,9.8 N时,喷涂层的压痕尖头出现裂纹,涂层平均断裂韧性为1.20 MPa·m^(1/2),载荷为2.94~9.8 N时,重熔后涂层的压痕尖头均没有观察到裂纹.

Remelting treatment of FeNiCrAl coating deposited by high-velocity arc spraying was conducted using laser technology.The m icrostructure,phase com position,microhardness and fracture toughness of the coating before and after remelting were analyzed.The results showed that the layer stack structure and pores of the spraying coating were elim inated,the microstructure of the coating became uniform and dense,and the interaction between the coating and the substrate were changed from mechanical combination to metallurgical bonding after rem elting.Compared w ith the phases of the spraying coating,which consisted of a-Fe and interm etallic compounds,such as AlFe3,AlFe and A l0 4Fe0 6,three more phases could be observed after rem elting,were a new phase of Fe-C r,the solid solution of[Fe,N i]and carbide NiCx.The average microhardness of the coating after remelting was 7.79 GPa,which was about 3 times than that of the substrate(2.5 GPa)and about 1.3 times than that of the spraying coating(6.0 GPa).In the indentation test of the spraying coating,the indentation cracks appeared at the loads of 4.9 and 9.8 N,corresponding to the average fracture toughness of spraying coating of 1.20 M Pa-m 1 2,while no crack was found during loading of 2.94~9.8 N after rem elting.