本論文是在研究TiFeCoNi等莫耳合金在鑄造狀態及1000℃熱處理後的電化學性質，熱處理時間分別為2、4、6以及24hr。以市售硫酸(98%)調配成1M的腐蝕溶液來測試合金的浸泡腐蝕速率；再以恆電流/恆電位儀測量此五種狀態下TiFeCoNi合金在0.25M、0.5M、0.75M及1M等不同濃度之硫酸溶液中的極化曲線，來測定其腐蝕電位、臨界電流及腐蝕速率，並與市售304不銹鋼作比較。
在電化學實驗中，TiFeCoNi合金在樹枝間相產生腐蝕現象，而硫酸濃度越高時，鈍態電流越大；退火時間越長時，鈍態電位越高。而TiFeCoNi合金在鑄造狀態及熱處理後之鈍態電位以及腐蝕電位皆優於304不銹鋼 。
TiFeCoNi合金在1M硫酸溶液之靜態浸泡腐蝕中，並沒有因為腐蝕現象使得重量減少，反而因為生成富Ti之生成物而使得重量增加，經過SEM和EDS的分析中，TiFeCoNi合金經過硫酸靜態浸泡腐蝕過程中，HCP結構之樹枝相較FCC結構之樹枝間相容易被腐蝕。 This thesis investigated the electrochemical properties of the as-cast and as-annealed TiFeCoNi equimolar alloys, the annealing temperature was fixed at 1000 °C and the annealing times were 2,4,6,24 hrs. These alloys were static immersed into 1M H2SO4 solution by measuring their corrosion rates. The polarization curves of the alloys under different conditions were done, the corrosion potentials, critical currents and corrosion rates of these alloys were also analyzed and compared with commercial 304 stainless steel.
The corrosion was occurred at the interdendritic regions of TiFeCoNi alloys by electrochemical tests. Increasing the concentration of the solution of H2SO4 would result in increasing the passive current; increasing the annealing time at 1000 °C would also result in increasing the passive potential. In addition, the passive currents and potentials of as-cast and as-annealed TiFeCoNi alloys all better than that of commercial 304 stainless steel.
No weight loss was found of as-cast and as-annealed TiFeCoNi alloys after static immersed in the solution of 1M H2SO4 solution for 28 days. The weight increasing of TiFeCoNi alloys were because of the forming of Ti-rich product. Moreover, the HCP-dendrites were easily corroded during static immersed into 1M H2SO4 solution by comparing with FCC-interdendrites.
