本實驗目的為開發低密度與高強度的多元高熵合金，目標密度低於5 g/cm3。所選取的元素為Al、Be、Si、Ti、Y，其密度皆小於5 g/cm3，另外再以五元高熵合金AlBeSiTiY為主要的合金成分，加入較重的元素V、Zr，以及另外再去掉Si與去掉Be為對照組。另外選取Al、B、Ni、Fe、Be、Si配置無Y系列合金。所有合金均以電弧熔煉方法配製，再經過研磨、拋光，探討其微結構、硬度以及熱性質。
研究發現AlBeSiTiY-Zr,V高熵合金除產生FCC固溶相外，還容易形成矽化物與Y – Al化合物。其中不加Si系列的合金，容易液相分離現象；不加Be系列的合金則有更大量的矽化物。
在本實驗中，以六元高熵合金AlBeSiTiYV的硬度值最高，可達HV860，是固溶強化與散佈強化機制發揮的極致。在五元合金方面硬度的表現，以AlBeSiTiY主要成分系列合金為最好，其硬度值皆高於HV700以上。
經由示差熱分析儀的量測，可以發現本實驗中除了不加Si之合金系列外，其餘合金在高溫1400 oC下皆相當穩定，而AlBeTiVY以及AlBeTiVYZr合金在大約1000 oC時會有局部融化產生。
由於本實驗之高熵合金密度皆小於5 g/cm3，除了AlBeTiVYZr之液相分離外，其比強度皆大於40，而鋁合金強度最強之7075 - T6合金的比強度為18.3、麻時效超強鋼的18Ni (350)的比強度為31.2，皆小於40，所以本實驗之AlBeSiTiY-V,Zr高熵合金之比強度高出傳統的高強度合金甚多。未來在輕量化工具、結構材、零組件以及耐磨表面的應用上相當有潛力。

The aim of this research is to develop light and high strength multi-component alloys with a density below 5 g/cm3. The major constituent elements of these multi-component alloys are Al, Be, Si, Ti, Y, that has a density below 5 g/cm3. Except for the major composition series, Si free series, Be free series and heavy elements (V and Zr) modified series were also investigated. These alloys were prepared by arc melting and their microstructure, hardness, and thermal properties were studied.
The results showed that the alloys form a major FCC solid solution and two precipitations, silicides and the Y-Al compounds, randomly distributed over the matrix . In Si free series, it was observed that the alloys have two main phases forming drop-lets in each other. In Be free series, there are silicides distribution over the matrix.
Among all the alloys, the composition, AlBeSiTiVY, exhibits the highest hardness of HV860. This may originate from the solid solution strengthening and precipitation hardening mechanisms. Over all 5-element alloys, AlBeSiTiY, exhibits the highest hardness above HV700. The hardness of Be free series is higher than that of Si free series.
From the DTA analysis, it was found that all alloys are stable at high temperature of 1400 oC except for Si free series. The alloys, AlBeTiVY and AlBeTiVYZr, partly melted at 1000 oC.
The density of all of the alloys is lower than 5 g/cm3, and the ratio of hardness to density is larger than 40, except AlBeTiVYZr. They are highly strengthened alloys. For instance, the ratio of hardness to density of the aluminum alloy, 7075 – 6T which is the hardest alloy in aluminum alloys, is 18.3. The ratio of 7075 - 6T is lower than that of high-entropy alloys, AlBeSiTiY-V,Zr. Therefore, it is very potential for industrial applications such as cutting tools, structural materials and wear resistance surface.

1. A. Inoue, K Kita, T. Masumoto, K. Ohtera, Japanese Journal of Applied Physics Part 2 – Letters, 27, 10, 1796 - 1799, (1998).
2. A. Inoue, K Kita, T. Masumoto, T. Zhang, Materials Transactions, JIM, 30, 9, 722 – 725, (1989).
3. A. Inoue - A, T. Zhang, T. Masumoto, Materials Transactions, JIM, 31, 3, 177 – 183, (1999).
4. A. Peker, W. L. Johnson, Applied Physics Letters, 63 17, 2342 – 2344, (1993).
5. A. Inoue, T. Zhang, K. Ohba, T. Shibata, Materials Transactions, JIM, 36, 7, 876 – 878, (1995).
6. D. V. Louzguine, A. Inoue, Materials Letters, 39, 211 – 214, (1999).
7. L. Q. Xing, C. Bertrand, J. P. Dallas, M. Cornet, Materials Science and Engineering, A241, 216 – 225, (1998).
8. 黃國雄， “等莫耳比多元合金系統之研究”，國立清華大學材料科學工程研究所碩士論文，1996。
9. 賴高廷，“高亂度合金微結構及性質探討”，國立清華大學材料科學工程研究所碩士論文，1998。
10.童重縉，“Cu – Co – Ni – Cr – Al – Fe 高熵合金變形結構與高溫特性之研究”，國立清華大學材料科學工程研究所碩士論文，2002。
11.許經佑，“B的添加對Cu – Co – Ni – Cr – Al0.5 – Fe 高熵合金微結構與高溫特性之研究“，國立清華大學材料科學工程研究所碩士論文，1998。
12. 胡雅惠，“以機械合金法製備Cu-Ni-Al-Co-Cr-Fe-Ti-Mo合金粉末微結構及性質之研究”，國立清華大學材料科學工程研究所碩士論文，2004。
13.吳浚民，“AlxCoCrCuFeNiTiy高熵合金黏著磨耗性質之研究”，國立清華大學材料科學工程研究所碩士論文，2004。
14.陳宣佑，“Al-Cr-Cu-Fe-Mn-Ni高熵合金變形及退火行為之研究”，國立清華大學材料科學工程研究所碩士論文，2004。
15.蔡哲瑋，CuCoNiCrAlxFe高熵合金加工變形及微結構之探討，國立清華大學材料科學工程研究所碩士論文，2003。
16. C. T. Sims, and W. C. Hagel, “The Superalloys”, John Wiley & Sons, New York, 1972.
17. C. T. Sims, ASTM Tech. Pub. 70-GT-24, (May 1970).
18. A. Inoue, Acta Mater., 48, 279 , (2000).
19. J. Kramer, Annln Phys., 37, 19, (1934).
20. A. Bremer, D. E. Couch and E. K. Williams, J. Res. Natn. Bur. Stand., 44, 109, (1950).
21. W. Klement, R.H. Willens, and P. Duwez, Nature, 187, 869, (1960).
22. P. Duwes, Trans. Am. Soc. Metals, 60, 607, (1967).
23.程天一,張守華編著, 快速凝固技術與新型合金, 宇航出版社, 1990
24. H. S. Chen, Reports on Progress in Physics 43 (4), 353, (1980)
25. H. W. Kui, A. L. Greer and D. Turnbull, Applied Physics Letters, 45, 6, 615-616, (1984).
26. H. W. Kui, D. Turnbull, Applied Physics Letters, 47, 796-797, (1985).
27. A. Inoue and K. Hashimoto, Amorphous and Nanocrystalline Materials, Springer, pp. 2-3, (2001).
28. A. Inoue, K. Ohtera, K. Kita and T.Masumoto, Japanese Journal of Applied Physics, 27, L2248, (1989).
29. A. Inoue, T. Zhang and T. Masumoto, Materials Transactions, JIM, 30, 965, (1989).
30. A. Inoue, T. Zhang and T. Masumoto, Materials Transactions, JIM, 31, 177, (1990).
31. A. Peker, W. L. Johnson, Applied Physics Letters, 63 17, 2342 – 2344, (1993).
32. A. Inoue and J. S. Gook, Materials Transactions JIM, 36 (10), 1282-1285, (1995).
33. A. Inoue, N. Nishiyama and T. Matsuda, Mterials Transactions JIM, 37 (2), 181-184, (1996).
34. Y. He, T. D. Shen and R. B. Schwarz, Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science, 29 (7), 1795-1804, (1998).
35. T. Zhang and A. Inoue, Materials Transactions JIM, 39 (10), 1001-1006, (1998).
36. A. Inoue and T. Zhang, Materials Transactions JIM, 40, 301, (1999).
37. A. Inoue, T. Zhang and A. Takeuchi, Applied Physics Letters, 71, (4), 464-466, (1997).
38. A. Inoue, T. Nakamura, T. Sugita, T. Zhang and T. Masumoto, Materials Transactions JIM, 34, (4), 351-358, (1993).
39. A. Inoue, T. Nakamura, N. Nishiyama and T. Masumoto, Materials Transactions JIM, 33, (10), 937-945, (1992).
40. A. Inoue, N. Nishiyama and H. Kimura, Materials Transactions JIM, 38, (2), 179-183, (1997).
41. 何圣靜、高莉如，非晶態材料及其應用，機械工業出版社，1987。
42. A. Inoue, Materials Transactions JIM, 36, 886, (1995).
43. A. Inoue, Materials Science And Engineering A-Structural Materials Properties Microstructure And Processing 226, 357-363, June (1997).
44. A. Inoue, T. Zhang, A. Takeuchi, Mechanically Alloyed, Metastable and Nanocrystalline Materials, part 2 Materials Science Forum 269-2, 855-864, part 2, (1998).
45. M. R. Bennett and J. G. Wright, Phys. Status Solid. (a), 13, 135, (1972).
46. P. Haasen, "Metallic Glasses", Journal of Non-Crystalline Solids, 56, 1-3, 191-199, (1983).
47. P. Haasen : Journal of Non-Crystalline Solids, 56, 191-199, (1983).
48. H. Jones, Rapid Solidification of Metals and Alloys, Inst. of Metallurgists, London, (1982).
49. B. B. Prasad, T. R. Anantharaman, A. K. Bhatnagar, D. Ganesan, and R. Jagannathan : Journal of Non-crystalline Solids, 1984, vol. 61-2, pp. 391-395.
50. J.W. Yeh, S. K. Chen, S. J. Lin, J. Y. Gan, T. S. Chin, T. T. Shun, C. H. Tsau, and S. Y. Chang, Advanced Engineering Materials 6 (5), 299-303, MAY (2004).
51. J.W. Yeh, S. K. Chen, J. Y. Gan, S. J. Lin, T. S. Chin, T. T. Shun, C. H. Tsau, and S. Y. Chang, Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science 35A (8), 2533-2536, AUG (2004).
52. A. L. Mackay, Crystallography Reports, 46, 4, 524-526, (2001). From Kristallografiya, 46, 4, 587-590, (2001).
53. Ihara H, Bushida K, Terada N, et al. Physica C 185, 1567-1568, Part 3, DEC (1991).
54. Gerhard Gille, J. Bredthauer, B Gries, B. Mende, and W. Heinrich, Int. J. of Refractory Metals and Hard Metals, 18, 87-102, (2000.)
55. F.R. de Boer, et al. Cohesion in metals :/transition metal alloys, Amsterdam ;North-Holland, 1988.
56. Thaddeus B. Massalski, Hiroaki Okamoto, P.R. Subramanian, Linda Kacprzak., Binary alloy phase diagrams, Materials Park, Ohio :ASM International, (1990)
57. William D. Callister, Jr., Materials Science and Engineering and Introsuction, John Silley & Sons, INC., (1993.)