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利用 5 k W CO2 激光器在铸造铝硅合金表面两次重熔预置合金粉末 ,制备出 Ni/WC梯度层 ,并对它们的显微组织进行了分析 .结果表明 ,在激光梯度层表面存在与单一激光合金化层不同的 Al3 Ni2 区和未熔碳化钨 ,而在单一激光合金化层中所有的碳化钨颗粒全部溶解 ;在激光梯度层内自基体至表面铝、镍等元素的含量变化较单一激光合金化层缓和 ,显微硬度呈现明显的梯度变化 ,而单一的激光合金化层显微硬度曲线存在一“平台”区 ,同基体组织之间硬度有较大差异
The Ni / WC gradient layers were prepared by remelting the alloy powders on the surface of the cast Al-Si alloy with a 5 k W CO2 laser and their microstructures were analyzed.The results show that there are Al3Ni2 zone and unmelted tungsten carbide in the single laser alloying layer, and all the tungsten carbide particles in the single laser alloying layer are completely dissolved. Compared with the laser gradient layer, the contents of Al, Ni and other elements in the laser gradient layer are relatively different Single laser alloying layer to ease, the microhardness showed a significant gradient change, and a single laser alloying layer microhardness curve exists in a “platform” area, with a significant difference between the hardness of the matrix