臺灣博碩士論文加值系統

本研究旨在探討新型的中低密度高熵合金之成分設計，其目標為設計出密度低於5 g/cm3的高熵合金且其微結構經過熱處理後仍維持在單一相或是雙相。首先由低密度的元素Ti以及Al為基底著手進行成份設計，配合符合高熵相關參數之模擬計算從TiAlX三元合金逐步添加不同的元素至四元合金以及五元合金，並經由實驗結果找出最合適的成分設計。合金原料先經由真空電弧熔煉及墜落鑄造後形成合金鑄錠，然後再置於真空高溫爐中進行 800℃/24小時均質化熱處理。鑄造狀態及處理後的試片再經研磨拋光後進行XRD微結構分析、OM和SEM/EDS金相觀察及硬度試驗。由微結構分析發現TiAlVCrFe (=5.72 g/cm3), TiAlVCrMn (=5.55 g/cm3), TiAlVCrCu (=5.61g/cm3) 三種五元高熵合金的鑄錠均為單一相BCC結構，其硬度均在Hv 650左右。此外，TiAlVCrFe (=5.72 g/cm3), TiAlVCrMn (=5.55 g/cm3) 高熵合金經800℃/24小時熱處理後，由於析出強化作用，其硬度提升至Hv 800。相信此兩種五元系列合金經微調增高其Ti和Al元素成份比率，將可獲得密度低於5 g/cm3且具有單一相或是雙相結構的高熵合金。

In this study, we tried to design the medium-low density high entropy alloys (HEAs) (contains at least 5 elements and the density of the alloys are below 5 g/cm3) by empirical phase-formation rules. Meanwhile, these HEAs should remain a structure of single phase or two phases after heat treatment. Therefore, we start to study the HEAs from the TiAlX alloy (3 elements), then add the fourth and fifth elements step by step based on the parameter calculation which related to the requirement of HEA. The high entropy alloys ingots were firstly prepared by vacuum arc-melting and drop casting, and then homogenizing at 800℃for 24h in vacuum. The as-cast and heat treated samples were characterized by XRD analysis, OM and SEM/ESD examination, and Vickers’ hardness test. The XRD results reveal that the as-cast TiAlVCrFe (=5.72 g/cm3), TiAlVCrMn (=5.55 g/cm3), TiAlVCrCu (=5.61 g/cm3) HEAs showed the BCC single structure with hardness around 670 Hv. Moreover, the hardness of TiAlVCrMn and TiAlVCrFe HEAs can reach to 800 Hv after annealing at 800°C for 24 hr in vacuum due to the precipitation hardening. It is believed that the goal of medium-low density for the 5-components HEAs can be achieved by increasing the Ti and Al molar ratio in our further study.

摘要 I
Abstract II
致謝 III
總目錄 IV
表目錄 VIII
圖目錄 IX
第一章 緒論 1
1-1前言 1
1-2研究目的 1
第二章 文獻回顧 3
2-1高熵合金之發展 3
2-1-1 高熵合金定義 3
2-2 高熵合金之合金相形成規則 4
2-2-1 形成固溶體之參數 5
2-3 高熵合金四大效應[19] 6
2-3-1高熵效應 6
2-3-2嚴重晶格應變效應 7
2-3-3遲緩擴散效應 8
2-3-4雞尾酒效應 9
2-4 低密度高熵合金 9
2-5 成份設計 11
第三章 成份設計與實驗方法 16
3-1固溶體 16
3-1-1 固溶體之相關參數計算 16
3-1-2 預測密度計算與真實密度量測 17
3-2 高熵合金製備 17
3-2-1 合金配製 17
3-2-2 合金熔煉 18
3-2-3 高熵合金棒材製作 18
3-3均質化熱處理 18
3-4 高熵合金微結構分析 19
3-4-1 X光繞射儀(XRD) 19
3-4-2 熱處理後冷卻速率對高熵合金微結構的影響 19
3-4-3光學顯微鏡(Optical Microscopy) 19
3-4-4 掃描式電子顯微鏡(SEM) 20
3-4-5 能量散射光譜儀(EDS) 20
3-5 熱性質分析 20
3-5-1 試片製作 20
3-5-2 熱示差掃描熱分析儀(DSC) 21
3-6 機械性質分析 21
3-6-1試片製作 21
3-6-2 維氏硬度測試 21
第四章 結果與討論 33
4-1 成份設計分析 33
4-1-1固溶體相關之參數計算結果 33
4-2 密度計算 35
4-3熱性質分析 36
4-4 X光繞射分析 37
4-5熱處理後冷卻速率對相的影響分析 38
4-6 OM微觀結構分析 38
4-7 SEM EDS分析 39
4-8 硬度分析 40
第五章、結論 74
第六章、參考文獻 75

1. ASM Handbook Volume 2: Properties and Selection: Nonferrous Alloys and Special-Purpose Materials. (1990). Materials Park, OH: ASM International.
2. ASM Handbook, Volume 1: Properties and Selection: Irons, Steels, and High-Performance Alloys. (1990). Materials Park: A S M International.
3. Singh, S., Wanderka, N., Murty, B., Glatzel, U. and Banhart, J. (2011). Decomposition in multi-component AlCoCrCuFeNi high-entropy alloy. Acta Materialia, 59(1), pp.182-190.
4. Hsu, C., Wang, W., Tang, W., Chen, S. and Yeh, J. (2010). Microstructure and Mechanical Properties of New AlCoxCrFeMo0.5Ni High-Entropy Alloys. Advanced Engineering Materials, 12(1-2), pp.44-49.
5. Chen, Y., Duval, T., Hung, U., Yeh, J. and Shih, H. (2005). Microstructure and electrochemical properties of high entropy alloys—a comparison with type-304 stainless steel. Corrosion Science, 47(9), pp.2257-2279.
6. Chen, Y., Hong, U., Shih, H., Yeh, J. and Duval, T. (2005). Electrochemical kinetics of the high entropy alloys in aqueous environments—a comparison with type 304 stainless steel. Corrosion Science, 47(11), pp.2679-2699.
7. Yang, X., Zhang, Y. and Liaw, P. (2012). Microstructure and Compressive Properties of NbTiVTaAlx High Entropy Alloys. Procedia Engineering, 36, pp.292-298.
8. Senkov, O., Scott, J., Senkova, S., Miracle, D. and Woodward, C. (2011). Microstructure and room temperature properties of a high-entropy TaNbHfZrTi alloy. Journal of Alloys and Compounds, 509(20), pp.6043-6048.
9. Lilensten, L., Couzinié, J., Perrière, L., Bourgon, J., Emery, N. and Guillot, I. (2014). New structure in refractory high-entropy alloys. Materials Letters, 132, pp.123-125.
10. Yeh, J., Chen, S., Lin, S., Gan, J., Chin, T., Shun, T., Tsau, C. and Chang, S. (2004). Nanostructured High-Entropy Alloys with Multiple Principal Elements: Novel Alloy Design Concepts and Outcomes. Advanced Engineering Materials, 6(5), pp.299-303.
11. Cantor, B., Chang, I., Knight, P. and Vincent, A. (2004). Microstructural development in equiatomic multicomponent alloys. Materials Science and Engineering: A, 375-377, pp.213-218.
12. Ranganathan, S. (2003). Alloyed pleasures: Multimetallic cocktails. CURRENT SCIENCE, 85(10), pp.1404-1406.
13. Yeh, J. (2006). Recent progress in high-entropy alloys. Annales de Chimie Science des Matériaux, 31(6), pp.633-648.
14. Takeuchi, A. and Inoue, A. (2001). Quantitative evaluation of critical cooling rate for metallic glasses. Materials Science and Engineering: A, 304-306, pp.446-451.
15. Miedema, A., de Châtel, P. and de Boer, F. (1980). Cohesion in alloys — fundamentals of a semi-empirical model. Physica B+C, 100(1), pp.1-28.
16. Cahn, R. and Haasen, P. (1996). Physical metallurgy. 4th ed. Amsterdam: North-Holland.
17. Zhang, Y., Zhou, Y., Lin, J., Chen, G. and Liaw, P. (2008). Solid-Solution Phase Formation Rules for Multi-component Alloys. Advanced Engineering Materials, 10(6), pp.534-538.
18. Yang, X. and Zhang, Y. (2012). Prediction of high-entropy stabilized solid-solution in multi-component alloys. Materials Chemistry and Physics, 132(2-3), pp.233-238.
19. Yeh, J. (2011). 高熵合金的發展. 華岡工程學報, (27), pp.1-18.
20. Gaskell, D. (1995). Introduction to the thermodynamics of materials. 3rd ed. Washington: Taylor & Francis, pp.80-84.
21. Swalin, R. (1972). Thermodynamics of solids. 2nd ed. New York: Wiley, pp.35-41.
22. Seitz, F. and Turnbull, D. (1964). Solid State Physics, 16. Burlington: Elsevier, p.404.
23. Tsai, K., Tsai, M. and Yeh, J. (2013). Sluggish diffusion in Co–Cr–Fe–Mn–Ni high-entropy alloys. Acta Materialia, 61(13), pp.4887-4897.
24. Dąbrowa, J., Cieślak, G., Stygar, M., Mroczka, K., Berent, K., Kulik, T. and Danielewski, M. (2017). Influence of Cu content on high temperature oxidation behavior of AlCoCrCuxFeNi high entropy alloys (x = 0; 0.5; 1). Intermetallics, 84, pp.52-61.
25. Wu, J., Lin, S., Yeh, J., Chen, S., Huang, Y. and Chen, H. (2006). Adhesive wear behavior of AlxCoCrCuFeNi high-entropy alloys as a function of aluminum content. Wear, 261(5-6), pp.513-519.
26. Yeh, J., Chang, S., Hong, Y., Chen, S. and Lin, S. (2007). Anomalous decrease in X-ray diffraction intensities of Cu–Ni–Al–Co–Cr–Fe–Si alloy systems with multi-principal elements. Materials Chemistry and Physics, 103(2007), pp.41–46
27. Murty, B., Yeh, J. and Ranganathan, S. (2014). High-entropy alloys. Oxford, UK: Butterworth-Heinemann.
28. Tong, C., Chen, M., Yeh, J., Lin, S., Chen, S., Shun, T. and Chang, S. (2005). Mechanical performance of the Al x CoCrCuFeNi high-entropy alloy system with multiprincipal elements. Metallurgical and Materials Transactions A, 36(5), pp.1263-1271.
29. Han, Z., Liu, X., Zhao, S., Shao, Y., Li, J. and Yao, K. (2015). Microstructure, phase stability and mechanical properties of Nb–Ni–Ti–Co–Zr and Nb–Ni–Ti–Co–Zr–Hf high entropy alloys. Progress in Natural Science: Materials International, 25(5), pp.365-369.
30. Cars on a diet : the material and energy impacts of passenger vehicle weight reduction in the U.S. (2011). Massachusetts Institute of Technology.
31. Miller, W., Zhuang, L., Bottema, J., Wittebrood, A., De Smet, P., Haszler, A. and Vieregge, A. (2000). Recent development in aluminium alloys for the automotive industry. Materials Science and Engineering: A, 280(1), pp.37-49.
32. Senkov, O., Senkova, S., Woodward, C. and Miracle, D. (2013). Low-density, refractory multi-principal element alloys of the Cr–Nb–Ti–V–Zr system: Microstructure and phase analysis. Acta Materialia, 61(5), pp.1545-1557.
33. Senkov, O., Senkova, S., Miracle, D. and Woodward, C. (2013). Mechanical properties of low-density, refractory multi-principal element alloys of the Cr–Nb–Ti–V–Zr system. Materials Science and Engineering: A, 565, pp.51-62.
34. Stepanov, N., Yurchenko, N., Shaysultanov, D., Salishchev, G. and Tikhonovsky, M. (2015). Effect of Al on structure and mechanical properties of AlxNbTiVZr (x = 0, 0.5, 1, 1.5) high entropy alloys. Materials Science and Technology, 31(10), pp.1184-1193.
35. A Novel Light High-Entropy Alloy Al20Be20Fe10Si15Ti35. Available online: http://www.science24.com/paper/19071 (accessed on 25 August 2016).
36. Li, R., Gao, J. and Fan, K. (2010). Study to Microstructure and Mechanical Properties of Mg Containing High Entropy Alloys. Materials Science Forum, 650, pp.265-271.
37. Li, R., Gao, J. and Fan, K. (2011). Microstructure and Mechanical Properties of MgMnAlZnCu High Entropy Alloy Cooling in Three Conditions. Materials Science Forum, 686, pp.235-241.
38. Chen, Y., Tsai, C., Juan, C., Chuang, M., Yeh, J., Chin, T. and Chen, S. (2010). Amorphization of equimolar alloys with HCP elements during mechanical alloying. Journal of Alloys and Compounds, 506(1), pp.210-215.
39. Youssef, K., Zaddach, A., Niu, C., Irving, D. and Koch, C. (2014). A Novel Low-Density, High-Hardness, High-entropy Alloy with Close-packed Single-phase Nanocrystalline Structures. Materials Research Letters, 3(2), pp.95-99.
40. Tsai, M. and Yeh, J. (2014). High-Entropy Alloys: A Critical Review. Materials Research Letters, 2(3), pp.107-123.
41. Senkov, O., Wilks, G., Scott, J. and Miracle, D. (2011). Mechanical properties of Nb25Mo25Ta25W25 and V20Nb20Mo20Ta20W20 refractory high entropy alloys. Intermetallics, 19(5), pp.698-706.
42. Zhang, Y. and Peng, W. (2012). Microstructural control and properties optimization of high-entropy alloys. Procedia Engineering, 27, pp.1169-1178.
43. Zhang, Y., Zhou, Y., Lin, J., Chen, G. and Liaw, P. (2008). Solid-Solution Phase Formation Rules for Multi-component Alloys. Advanced Engineering Materials, 10(6), pp.534-538.
44. GUO, S. and LIU, C. (2011). Phase stability in high entropy alloys: Formation of solid-solution phase or amorphous phase. Progress in Natural Science: Materials International, 21(6), pp.433-446.
45. Feng, R., Gao, M., Lee, C., Mathes, M., Zuo, T., Chen, S., Hawk, J., Zhang, Y. and Liaw, P. (2016). Design of Light-Weight High-Entropy Alloys. Entropy, 18(9), p.333.
46. Jin, C. (2004). 熱處理. Tai nan shi: Fu wen, p.71.