鋁合金具有質量輕、機械強度高、導電導熱性良好、易加工及價格低廉等優點，其應用範圍極廣，舉凡傳統工業、航太工業、電子工業等均有其舉足輕重的地位。然而鋁合金容易被磨損、熔點低、表面硬度低及耐磨耗性差等缺點，因此藉由雷射合金化方法改善表面性質。
本文主要研究利用YAG雷射法在6061鋁合金表面添加鎳基及鈷基粉末進行合金化，探討其耐磨耗性、顯微組織、成份、硬度等性質。由實驗結果得知:合金層可分為上表層、次表層、中間層、界面層，產生合金層變化原因取決於冷卻速率及密度比重等等，上表層與界面層因冷卻速率最快，鎳基合金層上表層形成Al3Ni組織，而次表層主要組織為Al3Ni2羽毛狀晶。中間層主要為AlNi組織。鈷基合金層上表層形成Al9Co2組織，次表層為Al13Co4組織，中間層為針狀Al5Co2組織，在硬度方面，經過雷射合金化處理後之鎳基及鈷基中間層硬度比基材高10倍左右。
經過不同速度及不同距離之磨耗測試及磨痕和磨屑的SEM觀察可以發現各自的輕微磨耗與嚴重磨耗的轉換點，從研究結果中發現鎳基耐磨耗性比基材好8倍，鈷基比基材好5倍，而經過熱處理後由於鎳基中間層會析出Al3Ni而硬度下降，因此轉換點在500m就產生了，而鈷基也是在500m時就失效了，因此本研究中耐磨耗性最佳的是未熱處理之鎳基試片。

Aluminum alloys have been considered to be one of the most versatile useful materials because of to interesting mechanical properties, such as high strength-weight ratio, high electrical conductivity, good themal conductivity, easy to shape, and relatively inexpensive. However, the low hardness, low melting point of such alloys result in poor friction properties and heat resistance. The YAG laser alloying is one of the efficient method to improve the surface wear resistance.
This paper is using YAG laser alloying Ni-based and Co-based powder on the surface of 6061 alloy and then to discuss the wear resistance property, microstructure, composition, and hardness throughout the alloying layers. As experimental result, we can find alloying layer can be divided into four layers, such as surface layer, subsurface layer, middle layer, and interface layer. The main reason to cause the variation of the alloying layer is due to different cooling rate and density. The Ni-based of the surface layer has the Al3Ni, the subsurface layer has Al3Ni2 feather-like microstructure, and the middle layer is AlNi . The Co-based of the surface layer has the Al9Co2, the subsurface layer is Al13Co4, and the middle layer is needle-like Al5Co2,and after laser alloying treatment, the hardness of middle layer of Ni-based and Co-based are 10 times higher than substrate.
We can find transition from mild wear to severe wear point from SEM of wear surface and wear debris, and from results, we can find the wear resistance of Ni-based alloy is 8 times better than substrate’s, and Co-based alloy is 5 times better than substrate. And after heat treatment, because the middle layer of Ni-based Al3Ni will segregate to reduce the hardness, it results in that the transition from mild wear to severe wear point reduce to 500m, and so is Co-based alloy, The optimum specimen of wear resistance is Ni-based alloy without heat treatment.

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