铝合金喷涂Y_(2)O_(3)和Ni混合粉扫描电子束表面合金化的研究

Study on Surface Alloying of Scanning Electron Beam with Aluminum Alloy Sprayed Y_(2)O_(3)and Ni Mixed Powder

扫描电子束表面合金化技术可改善铝合金表面性能。研究采用等离子热喷涂技术将不同含量的Y_(2)O_(3)与Ni混合粉末涂覆到6061铝合金表面,利用扫描电子束进行表面合金化处理。研究了表面合金化后强化层的组织形态、相结构和硬度的变化规律,探讨了稀土Y_(2)O_(3)含量与电子束工艺参数对强化层组织和性能的影响。结果表明,电子束表面合金化处理,其表面可分为合金化区、热影响区和基体区。合金化区的显微组织主要由YAl_(3)、AlNiY和Ni_(17)Y_(2)等相组成,最高硬度为396 HV0.2,是基体的6倍;热影响区主要由α-Al固溶体和Ni-Al化合物相组成,最高硬度为260 HV0.2,是基体的4倍;基体的相结构主要为α-Al和Mg_(2)Si强化相组成。随着稀土Y_(2)O_(3)含量的增加,合金层组织晶粒得到细化,硬度得到提升。稀土Y_(2)O_(3)含量为5%,组织细化程度与硬度提升最明显。强化层显微硬度随束流的增加先增加后减少,随移动速度的增加而减少,当电子束束流为10 mA、移动速度为10 mm/s,强化层组织晶粒高度细化,硬度提升显著。

Scanning electron beam surface alloying technology can improve the surface properties of aluminum alloy.Different content of Y_(2)O_(3)and Ni mixed powders were coated onto the surface of 6061 aluminum alloy using a plasma thermal spraying technique for surface alloying treatment using a scanning electron beam.The change of microstructure,phase structure and hardness of the strengthened layer after surface alloying was studied,and the influence of rare earth Y_(2)O_(3)content and electron beam process parameters on the microstructure and properties of the strengthened layer was discussed.The results show that the surface of the electron beam can be divided into alloying zone,heat affected zone and matrix zone.The microstructure of the alloying zone is mainly composed of YAl_(3),AlNiY and Ni_(17)Y_(2),with a maximum hardness of 396 HV0.2,which is six times than that of the matrix.The thermally affected zone is mainly composed ofα-Al solid solution and Ni-Al compound phase,with a maximum hardness of 260 HV0.2,which is four times than that of the matrix.The phase structure of the matrix is mainly composed ofα-Al and Mg_(2)Si reinforced phase.With the increase of rare earth Y_(2)O_(3)content,the microstructure grains of the alloy layer are refined and the hardness is improved.The content of rare earth Y_(2)O_(3)is 5%,and the degree of tissue refinement and hardness improvement are the most obvious.The microhardness of the strengthening layer increases first and then decreases with the increase of the beam flow,and decreases with the increase of the moving speed.When the electron beam flow is 10 mA and the moving speed is 10 mm/s,the grain height of microstructure of the strengthening layer is refined and the hardness is improved significantly.