高熵合金A1xCo1.5CrFeNi1.5Ti0.5Moy電化學孔蝕行為之研究

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Title:	高熵合金A1xCo1.5CrFeNi1.5Ti0.5Moy電化學孔蝕行為之研究
Authors:	何宗翰
Contributors:	材料科學與奈米科技研究所
Keywords:	高熵合金
Date:	2010
Issue Date:	2011-10-20 13:47:10 (UTC+8)
Abstract:	本研究主要是針對新開發之高熵合金孔蝕行為及其電化學特性之研究。實驗中以高熵合金Al0.1Co1.5CrFeNi1.5Ti0.5Mo0.1為基本試驗材料，並分別改變Al含量以及Mo含量以探討這兩種金屬在高熵合金電化學實驗中所扮演的角色，並與304不鏽鋼作比較。 Al0.1-Mo0.1之高熵合金與304在0.1M NaCl中可知高熵合金具有較好的抗腐蝕效果，接著改變不同種類之氯鹽-NH4Cl可知NH4Cl對高熵合金孔蝕能力明顯比NaCl明顯，且其濃度越高，孔蝕力越強。而以實驗中所選用的高熵合金抗孔蝕能力依序排列為Al0.1-Mo0.2＞Al0.1-Mo0.1＞Al0.2-Mo0.1。而Al0.1-Mo0.1高熵合金於NH4Cl中CPT溫度隨著濃度的升高而下降。由高熵合金在陽極極化曲線中可知腐蝕電位與Cl鹽濃度並無太大關係，影響腐蝕電位的為Cl鹽種類與高熵合金種類。由SEM圖中，高熵合金未孔蝕前的腐蝕可看出合金呈現樹枝狀結構，其腐蝕發生的地方為樹枝間。在到達臨界孔蝕溫度後，高熵合金孔蝕情形亦趨嚴重，並擴大，加深。 This study is mainly focused on the electrochemical pitting corrosion behavior of the newly developed high entropy alloy. In the experiment, the roles played by Al and Mo in the Al0.1Co1.5CrFeNi1.5Ti0.5Mo0.1high entropy alloy on the electrochemistry were evaluated and compared with type 304 stainless steel. The result shows that high entropy Al0.1-Mo0.1 has a better corrosion resistance than type 304 stainless steel in 0.1M NaCl solution. Other salt like NH4Clwas also used and the result indicated that high entropy alloy has a less pitting corrosion resistance, the higher the salt concentration, the less the pitting resistance. In this respect, the alloys with varying Al and Mo can be arranged in the following order starting with the highest pitting corrosion resistance : Al0.1-Mo0.2>Al0.1-Mo0.1>Al0.2-Mo0.1.The critical pitting temperature (CPT) of the Al0.1-Mo0.1 in NH4Cl solution decreases as the NH4Cl concentration increases. The corrosion potential (Ecorr) has been less affected by the chloride (Cl-) concentration, but significantly affected by the type of chloride salts as well as the alloying composition of the sample alloy. The result of SEM indicated a dendritic structure of the alloy to start with and the actual corrosion took place at the interdendritic regions. Once the CPT being surpassed, the pitting situation of the high entropy alloy tends to be serious.
Appears in Collections:	[Department of Chemical & Materials Engineering] thesis

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