铸造铝合金表面激光熔凝合金化改性

Laser Surface Alloying of Cast Aluminum Alloy with Ni-Cr-Si-Nb-B Powder Mixture

将NiCrSiNbB合金粉末用聚合物调和成糊状并涂于Al3 19铸造铝合金试样表面 ,用CO2 激光以不同功率、不同的光斑移动速度处理涂层 ,使其快速熔凝形成耐磨的合金化层·实验结果表明 ,工艺参数严重地影响熔凝后合金化层的性能 ;可得到显微硬度达 14 0 0HV的高硬度层 ;选用合适的功率、光斑运动速度及预涂层厚度可得到单个处理轨迹、多道搭接处理及整个试样表面处理的无明显气孔、裂纹缺陷的组织细密的合金化层 ;层内主要强化相为AlNi和不同比例的Al,Ni金属间化合物·最终得到的表面合金化层的硬度比基体高 60HV～ 10 0HV ,其耐磨性与基材相比提高 3～

A CW CO 2 laser is used to treat the sample surface for improving wear properties of Al319. A two step processing is employed. The results shown that alloying parameters affect the properties of the alloying layer greatly. In some case,the hardness of the layer can reach up to 1?400?HV. A perfect surface alloying layer can be achieved by choosing the appropriate laser power and traveling speed. The grains of the surface alloying layer are very fine. It consists of Al phase, AlNi and others Al/Ni intermetallic phases. The hardness of the alloying layer is generally 60～100?HV higher than substrate materials. The result of wear test indicates that wear resistance of the alloying layer is improved greatly.