本研究主要探討7075鋁合金表面添加鎳基、鈷基合金粉末後，再利用Nd: YAG雷射進行合金化，在不同功率與走速條件下，觀察其表面顯微組織、微硬度及電化學性質之變化。

實驗結果顯示，鎳基合金層形成Al3Ni2與Al3Ni樹枝狀晶，鈷基合金層則形成Al9Co2、Al13Co4與Al11Cr2，顯微組織主要取決於冷卻速率快慢與合金元素之富集與否。微硬度結果顯示在鎳基或鈷基試片，微硬度較基材最高提升9倍之多，達900 HV。鎳基與鈷基試片之開路電位值在3.5 wt% NaCl水溶液中相當穩定，為 -0.9 V。電位動電位極化曲線結果顯示，鎳基與鈷基合金層可提高其在 3.5 wt% NaCl溶液中之腐蝕電位、保護電位，但孔蝕電位則與7075鋁基材本身相當。動電位測試後SEM觀察發現合金層之Al基材流失，殘留Al-Ni與Al-Co合金組織。鎳基試片在走速900 mm/min，功率1400 W時重量損失最少，為0.08 g。而鈷基試片則在走速600 mm/min，功率1400 W時，重量損失最少，為0.06 g。

The microstructure, Vicker’s microhardness, and electrochemical property on 7075 Al-Zn-Mg-Cu alloy surface coated by Nd: YAG laser surface alloying (LSA) with Ni base and Co base powder have been investigated.
The experimental results showed that the Al3Ni, Al3Ni2 dendrites existed in the Ni base alloy layer, and the Al9Co2, Al13Co4, Al11Cr2 dendrites existed in the Co base alloy layer respectively. The microstructure was decided by the cooling rate and distribution of alloy elements in LSA layers. The microhardness was raised to HV 900 for Ni base and Co base specimens, which is nine times to the matrix. The OCP was -0.9 V for Ni base and Co base alloyed layers in 3.5 wt% NaCl solution. The results of potentiodynamic polarization test showed that corrosion potential and protection potential were increased for Ni base and Co base alloyed layers, but the pitting potential was similar with 7075 alloy. The SEM images after PD test showed the aluminum in the Ni base and Co base alloyed layers flow away. The Al-Ni, Al-Co and Al-Cr IMCs were remained on the surface after PD test. Ni base specimen showed the minimum weight loss of 0.08 g at velocity for 900 mm/min and power for 1400 W. And, Co base specimen showed the minimum weight loss of 0.06 g at velocity for 600 mm/min and power for 1400 W.

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