本論文主要致力於CrFeCoNiMoxNbx高熵合金之微結構和電化學性質，合金成分是CrFeCoNiMo、CrFeCoNiNb和CrFeCoNiMo0.5Nb0.5三種合金。實驗結果可得知，添加Mo及Nb後合金微結構由CrFeCoNi晶粒狀組織變為雙相的樹枝狀組織。CrFeCoNiNb和CrFeCoNiMo合金中的兩相為晶格常數較大的complex cubic相及FCC相，其中樹枝相為complex cubic結構，而樹枝間相的基地相為FCC結構；而CrFeCoNiMo0.5Nb0.5合金中的兩相為HCP及FCC相，其中樹枝相為HCP結構，而樹枝間相的基地相亦為FCC結構。本實驗再以恆電流/恆電位儀測量金屬合金在1M之除氧硫酸、鹽酸、硝酸及氯化鈉溶液，在不同溫度下的極化曲線，來測定其腐蝕電位、腐蝕電流和鈍態區間電位，並且在相互做比較。隨著溫度的升高，每種合金在不同溶液中的情形不盡相同，有的鈍態區會漸漸消失，亦有腐蝕電位Ecorr和icorr會出現並非穩定的趨勢，所以可以在後面結論上，可以看到圖或表格呈現出不同的資訊。另外，本實驗配置之合金均和304不銹鋼的測試結果作比較，結果顯示CrFeCoNiMo、CrFeCoNiNb和CrFeCoNiMo0.5Nb0.5三種合金在這四種溶液中均優於304不銹鋼。
This thesis investigated the microstructures and electrochemistry properties of CrFeCoNiMoxNbx high-entropy alloys, which compositions were CrFeCoNiMo, CrFeCoNiNb and CrFeCoNiMo0.5Nb0.5 alloys. Results indicated that the microstructures of these alloys were changed from a granular structure of CrFeCoNi alloy to dendritic structures after adding Nb and/or Mo. The dendrites of CrFeCoNiNb and CrFeCoNiMo alloys were complex cubic phases, and the interdendrites were eutectic structures of FCC and complex cubic phases. In addition, the dendrite of CrFeCoNiMo0.5Nb0.5 alloys was a HCP phase, and the interdendrite was a eutectic structure of FCC and HCP phases. The polarization tests of these alloys in deaerated 1M H2SO4, HNO3, HCl and NaCl solutions at different temperatures were also measured in a potentiostat/galvanostat. The results were also compared with commercial 304 stainless steel. All of these CrFeCoNiMoxNbx high-entropy alloys were better than 304 stainless steel in these four solutions.
