【摘要】 利用SEM、EDS、磨损试验机及硬度测试仪等设备对铝合金表面激光熔覆层的组织与磨损性能开展了研究。结果表明,当扫描速度为5 mm/s时,熔覆层气孔、裂纹等缺陷相对较少;在熔覆层顶部生成了许多块状及网状的Ni-Al金属间化合物,中部生成了(Ni, Cr,Fe)_xC_y金属间化合物,底部存在大量具有明显生长方向性的柱状α-Al枝晶。熔覆层顶部及中部保持着高硬度值,中部硬度最高值达8200MPa,是熔覆层底部硬度值的5倍以上。硬度值在熔覆层中部的末端开始显著下降。熔覆层的摩擦系数根据载荷不同其值在0.37～0.43间变化,并随着载荷增加而有所降低。Ni-Al和(Ni, Cr, Fe)_xC_y金属间化合物等强化相在熔覆层中的生成及其在在熔覆层中上层的均匀分布是改善材料硬度及磨损性能的主要原因。更多还原

【Abstract】 The microstructure and wear properties of Ni-based composite coatings on aluminum alloy prepared by laser cladding were investigated by SEM, EDS, microhardness tester and friction tester. The results show that there are relatively few holes and cracks in the layer when the scanning speed is 5 mm/s. Many massive and continuous network Ni-Al intermetallic compounds form on the top of the cladding layer, and(Ni, Cr, Fe)_xC_y intermetallic compounds form at the middle of the cladding layer. The microstructure of the bottom cladding layer consists of the columnar α-Al dendrite with obvious growth direction. The middle and top of the cladding layer maintain a high microhardness value. The maximum microhardness of the middle of layer is 8200 MPa, which is more than 5 times larger than that of the bottom cladding layer. The microhardness decreases sharply at the end of the middle of layer. The friction coefficients of the layer have a fluctuation under different loads, and decrease with increasing the load. The formation and distribution of Ni-Al and(Ni, Cr, Fe)_xC_y intermetallic on the top and middle of the cladding layer are the primary reason for the improvement of the microhardness and wear of the layer.更多还原