Fe-Ni-Co-Ti-Cr-Mo-Nb高熵合金微結構及機械性質之研究

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Title:	Fe-Ni-Co-Ti-Cr-Mo-Nb高熵合金微結構及機械性質之研究 A study on the microstructures and mechanical properties of Fe-Ni-Co-Ti-Cr-Mo-Nb high-entropy alloys
Authors:	王聖元
Contributors:	材料科學與奈米科技研究所
Keywords:	高熵合金硬度非晶質微結構機械熱性質抗氧化性 Fe-Ni-Co-Ti-Cr-Mo-Nb microstructures high-entropy alloys
Date:	2006
Issue Date:	2014-06-09 12:58:49 (UTC+8)
Abstract:	本實驗以FeNiCoTiCr合金為基礎，繼續添加高溫元素Mo及/或 Nb成為六元及七元合金，以真空電弧熔煉技術，自行製作成六組多元高熵合金，再經過研磨、拋光，藉以探討其微結構、機械性質及熱性質之研究，並分析微結構對此性質的影響。研究顯示FeNiCoTiCrMoNb所組成的不同合金系統，其晶體結構以HCP及FCC為主，其中以 FeNiCo三元高熵合金為單一FCC相，其它組合金都有著至少兩相存在。研究發現隨著合金中不同原子尺寸的元素增多，固溶強化效應相對變強，再加上微晶強化、鍵結增強及非晶質無差排綜合表現等因素下，使得高熵合金材料具有極高的硬度值。在本實驗中以FeNiCoTiCrMo六元高熵合金硬度最高，其硬度值高達HV833，是固溶強化與散佈強化機制發揮的極致。在熱重量分析得知高熵合金抗氧化情形，在合金成份中，單獨添加高溫元素Nb，仍比添加高溫元素Mo其抗氧化性來的好，FeNiCoTiCrNb六元高熵合金，抗氧化能力最佳。雖有微量的氧化，並使得重量增加，在乾空氣下加熱到800 °C時，其變化量仍低於0.5 %。另外其他幾組等莫耳高熵合金在高溫下也都皆具備良好抗氧化性。 The microstructures, mechanical properties and thermal properties of the six-element and seven-element alloys of FeNiCoTiCr(Mo and/or Nb) were examined in this study, and analyzed the effects of microstructures on these properties. The results indicated that the FeNiCo was only single FCC phase alloy; the other alloys had two or three phases at least, the major phases in these alloys were HCP or FCC phases. The increasing of solid solution strengthening effect was examined with increasing the number of different elements with different sizes. The FeNiCoTiCrMo alloy had the highest hardness value of HV 833 among these alloys. It was the result of combination of the effects, such as grain refinement strengthening, dispersion strengthening, bonding energy strengthening and amorphous phase with free dislocation existing. Additionally, adding the sixth element of Nb into FeNiCoTiCr alloy possessed the better high-temperature oxidation resistance rather than adding the other high-melting point element of Mo. The weight increment of the FeNiCoTiCrNb alloy by thermogravimetry analysis in a atmosphere of dry air was less than 0.5 wt.% when the test temperature was up to 800°C. However, the other alloys in this study also exhibited good high-temperature oxidation resistance.
Appears in Collections:	[Department of Chemical & Materials Engineering] thesis

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