本研究主要探討FeCoNiCrAl0.5塊狀高熵合金之環境腐蝕行為。將高週波熔煉法熔鑄之FeCoNiCrAl0.5五元高熵合金施以不同溫度時效熱處理，藉以探討於不同水溶液環境下之腐蝕行為及微結構觀察。將3.5 wt% NaCl、1N NaOH和1N H2SO4水溶液之實驗結果，與304L不銹鋼極化曲線比較；於3.5 wt% NaCl 水溶液之極化數據比較中，304L不銹鋼得到最低之腐蝕速率、FeCoNiCrAl0.5高熵合金具有最高之腐蝕速率；NaOH水溶液之極化數據比較中，304L不銹鋼得到最低之腐蝕速率、FeCoNiCrAl0.5高熵合金具有最高之腐蝕速率；於H2SO4水溶液之極化數據比較中，304L不銹鋼得到最高之腐蝕速率、FeCoNiCrAl0.5高熵合金得到最低之腐蝕速率，其中又以FeCoNiCrAl0.5高熵合金經由3.5 wt% NaCl 水溶液之FeCoNiCrAl 0.5塊狀高熵合金具有較差之抗蝕性，研判為FeCoNiCrAl 0.5高熵合金中含富Cr相形成，造成水溶液中氯離子易對Cr相攻擊反而造成腐蝕速率加快，抗蝕性變差。隨著熱處理溫度上升，FeCoNiCrAl0.5高熵合金的硬度變高。

The corrosion behavior of FeCoNiCrAl0.5 bulky high entropy alloy was studied. The homogenization treatment of the as-cast alloy specimen was processed. After water quenching serial heat-treatment processes were carried out. The corrosion properties, mechanical properties and microstructures of the specimens had been evaluated after the immersion tests with the NaCl, NaOH and H2SO4 solutions, respectively. The alloy has higher corrosion rate in 3.5 wt% NaCl aqueous solutions due to significant segregation of Cr-riched phase. Because of the active sensitivity zone of appreciable potential difference the alloy was preferentially attacked along the Cr-riched phase. The alloy exhibits excellent hardness after the immersion tests in NaOH and H2SO4 solution.

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