本研究針對先進的高熵合金材料進行合金設計，以開發具高溫應用價值之新合金成分。參考目前最廣泛使用的高溫應用超合金材料，新型高溫合金的微結構也控制成面心立方基地相(γ)搭配均勻散佈有序L12析出強化相(γ′)之兩相結構，以兼顧良好的高溫機械強度及延展性。本研究首先提高有序Ni3Al相的固溶量，並研究其相穩定性及強度，結果發現高度固溶對γ′相的強化效果相當顯著，其原因來自較高的防相界能量(anti-phase boundary energy)；但高固溶所造成的混亂原子排列則會降低γ′的高溫穩定性。接著我們進一步針對γ - γ′兩相結構之合金進行高熵化的探討，結果發現熵值(entropy)提高的同時，也要顧及L12相的焓(enthalpy)值，否則此有序相的高溫穩定性也會明顯下降。經過系統化之合金設計，此種新開發超合金之基地相已跳脫傳統以鎳(Ni)、鈷(Co)、鐵(Fe)為基底之想法，而是以鎳－鈷－鐵基為主體，相較傳統超合金是屬於新的研究領域。進一步的研究證實，此較高混亂度的基底相能固溶更多的元素添加，且維持良好的高溫相穩定性，因此我們將其命名為「高熵超合金」。為了減少高溫時晶界脆弱的問題，我們成功將高熵超合金進行方向性鑄造，再進行各式高溫機械強度的研究。結果顯示此鑄造型合金能展現與傳統超合金相匹配的高溫硬度、高溫拉伸強度及高溫潛變特性，其原因可歸功於：優異的高溫相穩定性、高體積百分比的析出強化相、高的防相界能量(anti-phase boundary energy)以強化L12相及低的疊差能(stacking fault energy)以阻礙差排之爬升移動；高熵超合金也表現出良好的表面穩定性，在高溫氧化及熱腐蝕之環境中，緻密的氧化鋁或氧化鉻保護層能迅速生成，有效減緩侵蝕；此外與傳統超合金相比，高熵超合金的耐火強化元素添加量較少，因此具有低密度及低成本等優勢。但是我們也發現，此種合金在高溫下的析出相粗化現象無助於提昇潛變組抗能力，且基底相的強度較傳統超合金來的弱，因此仍有合金設計的優化空間。總結來說，本研究開發之高熵超合金，具有獨特的成分配比、良好的高溫性質及更佳的性能價格比，因此有潛力成為新世代的高溫應用材料。

In this study, high entropy alloys have been developed toward high temperature applications. According to the most widely used high temperature material superalloys, the microstructure of face-centered cubic (FCC) γ matrix with uniformly distributed L12 γ′ precipitates implies the more balanced high temperature strength and ductility. So, the thermal stability and strength of highly alloyed Ni3Al were studied initially. The strengthening effect on developing a γ′ composition toward higher entropy is significant, due to higher anti-phase boundary energy of the order phase. However, the order-disorder transition temperature would be decreased with the more random atomic distribution in γ′ lattice. The microstructure stability of the γ - γ′ alloys with medium to high mixing entropy were then studied. It was found that the high temperature alloys cannot be solely designed by entropy term, but should also enhance the ordering enthalpy of γ′ phase, to avoid lowering the thermal stability of γ′ phase. Through alloy designs, we have also found that present alloys are quite different from the conventional Ni-, Co- or Fe-based alloy design, but is within a range of stable (Ni, Co, Fe)-rich system. This composition space has rarely been studied through the development of superalloys. In addition, such highly-soluted (Ni-Co-Fe) matrix can exhibit an enlarged solubility of alloying contents, while remains good phase stability till high temperatures. Therefore, they have been named as high entropy superalloys (HESA). Since grain boundaries might be drawbacks to the thermal properties, HESAs have been successfully casted into the directionally-solidified (DS) structure by Bridgeman method. In terms of the high temperature mechanical properties, HESAs can exhibit comparable high temperature hardness, tensile strength and creep resistance to that of commercial superalloys due to the stable γ - γ′ microstructure, high volume fraction of γ′ precipitates, high anti-phase boundary energy for γ′ strengthening and low stacking fault energy to hinder dislocation climb. Good surface stability of HESA in high temperature oxidizing and corrosive environments were also demonstrated, which can be attributed to the rapid formation of continuous Chromia or Alumina for surface protection. Furthermore, with less alloying of refractory elements, HESAs exhibit the apparent advantages in lower density and cost of materials. Nevertheless, there are still concerns such as the directional coarsening of γ′ for HESAs cannot contribute to the creep resistance, and the strength of γ matrix is still lower than that of superalloys. As a result, further rooms for composition optimization of HESA exist. To summary, the novel high entropy superalloys are with unique composition, good thermal properties and improved cost-performance, thus can be promising as a new type of high temperature alloy.

[1] R.C. Reed, The Superalloys: Fundamentals and Applications, Cambridge University Press, UK, 2006.
[2] P. Caron, T. Khan, Evolution of Ni-based superalloys for single crystal gas turbine blade applications, Aerospace Science and Technology, 3 (1999) 513-523.
[3] D. Furrer, H. Fecht, Ni-based superalloys for turbine discs, JOM, 51 (1999) 14-17.
[4] T.M. Pollock, S. Tin, Nickel-based superalloys for advanced turbine engines: Chemistry, microstructure, and properties, Journal of Propulsion and Power, 22 (2006) 361-374.
[5] J.B. Wahl, K. Harris, New Single Crystal Superalloys, CMSX®-7 and CMSX®-8, Superalloys, (2012) 177-188.
[6] Y. Zhang, T.T. Zuo, Z. Tang, M.C. Gao, K.A. Dahmen, P.K. Liaw, Z.P. Lu, Microstructures and properties of high-entropy alloys, Progress in Materials Science, 61 (2014) 1-93.
[7] M.H. Tsai, J.W. Yeh, High-entropy alloys: a critical review, Materials Research Letters, 2 (2014) 107-123.
[8] M. Nathal, Effect of initial gamma prime size on the elevated temperature creep properties of single crystal nickel base superalloys, Metallurgical Transactions A, 18 (1987) 1961-1970.
[9] A.C. Yeh, S. Tin, Effects of Ru and Re additions on the high temperature flow stresses of Ni-base single crystal superalloys, Scripta Materilia, 52 (2005) 519-524.
[10] H.A. Roth, C.L. Davis, R.C. Thomson, Modeling solid solution strengthening in nickel alloys, Metallurgical and Materials Transactions A, 28 (1997) 1329-1335.
[11] F.I. Versnyder, M. Shank, The development of columnar grain and single crystal high temperature materials through directional solidification, Materials Science and Engineering, 6 (1970) 213-247.
[12] R. Reed, T. Tao, N. Warnken, Alloys-by-design: application to nickel-based single crystal superalloys, Acta Materialia, 57 (2009) 5898-5913.
[13] R.A. MacKay, T.P. Gabb, J.L. Smialek, M.V. Nathal, Alloy design challenge: development of low density superalloys for turbine blade applications, (2009).
[14] J.W. Yeh, S.K. Chen, S.J. Lin, J.Y. Gan, T.S. Chin, T.T. Shun, C.H. Tsau, S.Y. Chang, Nanostructured high-entropy alloys with multiple principal elements: Novel alloy design concepts and outcomes, Advanced Engineering Materials, 6 (2004) 299-303.
[15] Y.F. Ye, Q. Wang, J. Lu, C.T. Liu, Y. Yang, High-entropy alloy: challenges and prospects, Materials Today, 19 (2016) 349-362.
[16] J.W. Yeh, Recent progress in high entropy alloys, annales de chimie-science des materiaux, 31 (2006) 633-648.
[17] M.H. Tsai, Physical properties of high entropy alloys, Entropy, 15 (2013) 5338-5345.
[18] C.J. Tong, Y.L. Chen, J.W. Yeh, S.J. Lin, S.K. Chen, T.T. Shun, C.H. Tsau, S.Y. Chang, Microstructure characterization of AlxCoCrCuFeNi high-entropy alloy system with multiprincipal elements, Metallurgical and Materials Transactions A, 36 (2005) 881-893.
[19] K.Y. Tsai, M.H. Tsai, J.W. Yeh, Sluggish diffusion in Co-Cr-Fe-Mn-Ni high-entropy alloys, Acta Materialia, 61 (2013) 4887-4897.
[20] H.S. Oh, D. Ma, G.P. Leyson, B. Grabowski, E.S. Park, F. Körmann, D. Raabe, Lattice Distortions in the FeCoNiCrMn High Entropy Alloy Studied by Theory and Experiment, Entropy, 18 (2016) 321.
[21] J.W. Yeh, Alloy design strategies and future trends in high-entropy alloys, JOM, 65 (2013) 1759-1771.
[22] E.J. Pickering, N.G. Jones, High-entropy alloys: a critical assessment of their founding principles and future prospects, International Materials Reviews, 61 (2016) 183-202.
[23] D. Miracle, O. Senkov, A critical review of high entropy alloys and related concepts, Acta Materialia, 122 (2017) 448-511.
[24] B. Gludovatz, A. Hohenwarter, D. Catoor, E.H. Chang, E.P. George, R.O. Ritchie, A fracture-resistant high-entropy alloy for cryogenic applications, Science, 345 (2014) 1153-1158.
[25] K. Youssef, A. Zaddach, C.N. Niu, D. Irving, C. Koch, A Novel Low-Density, High-Hardness, High entropy Alloy with Close-packed Single-phase Nanocrystalline Structures, Materials Research Letters, 3 (2015) 95-99.
[26] Y. Zhang, T. Zuo, Y. Cheng, P.K. Liaw, High-entropy alloys with high saturation magnetization, electrical resistivity, and malleability, Scientific reports, 3 (2013).
[27] C. Lee, Y. Chen, C. Hsu, J. Yeh, H. Shih, The Effect of Boron on the Corrosion Resistance of the High Entropy Alloys Al0.5CoCrCuFeNiBx, Journal of The Electrochemical Society, 154 (2007) 424-430.
[28] H.M. Daoud, A.M. Manzoni, R. Völkl, N. Wanderka, U. Glatzel, Oxidation Behavior of Al8Co17Cr17Cu8Fe17Ni33, Al23Co15Cr23Cu8Fe15Ni15, and Al17Co17Cr17Cu17Fe17Ni17 Compositionally Complex Alloys (High‐Entropy Alloys) at Elevated Temperatures in Air, Advanced Engineering Materials, 17 (2015) 1134-1141.
[29] D.B. Miracle, J.D. Miller, O.N. Senkov, C. Woodward, M.D. Uchic, J. Tiley, Exploration and development of high entropy alloys for structural applications, Entropy, 16 (2014) 494-525.
[30] M.H. Chuang, M.H. Tsai, W.R. Wang, S.J. Lin, J.W. Yeh, Microstructure and wear behavior of AlxCo1.5CrFeNi1.5Tiy high-entropy alloys, Acta Materialia, 59 (2011) 6308-6317.
[31] P. Li, A. Wang, C. Liu, A ductile high entropy alloy with attractive magnetic properties, Journal of Alloys and Compounds, 694 (2017) 55-60.
[32] C.Y. Hsu, J.W. Yeh, S.K. Chen, T.T. Shun, Wear resistance and high-temperature compression strength of FCC CuCoNiCrAl0.5Fe alloy with boron addition, Metallurgical and Materials Transactions A, 35 (2004) 1465-1469.
[33] C.W. Tsai, M.H. Tsai, J.W. Yeh, C.C. Yang, Effect of temperature on mechanical properties of Al0.5CoCrCuFeNi wrought alloy, Journal of Alloys and Compounds, 490 (2010) 160-165.
[34] C.Y. Hsu, C.C. Juan, W.R. Wang, T.S. Sheu, J.W. Yeh, S.K. Chen, On the superior hot hardness and softening resistance of AlCoCrxFeMo0.5Ni high-entropy alloys, Materials Science and Engineering: A, 528 (2011) 3581-3588.
[35] F. Otto, A. Dlouhý, C. Somsen, H. Bei, G. Eggeler, E.P. George, The influences of temperature and microstructure on the tensile properties of a CoCrFeMnNi high-entropy alloy, Acta Materialia, 61 (2013) 5743-5755.
[36] Z. Wu, H. Bei, G.M. Pharr, E.P. George, Temperature dependence of the mechanical properties of equiatomic solid solution alloys with face-centered cubic crystal structures, Acta Materialia, 81 (2014) 428-441.
[37] J. He, C. Zhu, D. Zhou, W. Liu, T. Nieh, Z. Lu, Steady state flow of the FeCoNiCrMn high entropy alloy at elevated temperatures, Intermetallics, 55 (2014) 9-14.
[38] T.S. Cao, J.L. Shang, J. Zhao, C.Q. Cheng, R. Wang, H. Wang, The influence of Al elements on the structure and the creep behavior of AlxCoCrFeNi high entropy alloys, Materials Letters, 164 (2016) 344-347.
[39] A. Gali, E.P. George, Tensile properties of high- and medium-entropy alloys, Intermetallics, 39 (2013) 74-78.
[40] Z. Lu, H. Wang, M. Chen, I. Baker, J. Yeh, C. Liu, T. Nieh, An assessment on the future development of high-entropy alloys: summary from a recent workshop, Intermetallics, 66 (2015) 67-76.
[41] W.H. Liu, J.Y. He, H.L. Huang, H. Wang, Z.P. Lu, C.T. Liu, Effects of Nb additions on the microstructure and mechanical property of CoCrFeNi high-entropy alloys, Intermetallics, 60 (2015) 1-8.
[42] F. He, Z.J. Wang, S.Z. Niu, Q.F. Wu, J.J. Li, J.C. Wang, C.T. Liu, Y.Y. Dang, Strengthening the CoCrFeNiNb0.25 high entropy alloy by FCC precipitate, Journal of Alloys and Compounds, 667 (2016) 53-57.
[43] W.R. Wang, W.L. Wang, S.C. Wang, Y.C. Tsai, C.H. Lai, J.W. Yeh, Effects of Al addition on the microstructure and mechanical property of AlxCoCrFeNi high-entropy alloys, Intermetallics, 26 (2012) 44-51.
[44] J. Joseph, T. Jarvis, X. Wu, N. Stanford, P. Hodgson, D.M. Fabijanic, Comparative study of the microstructures and mechanical properties of direct laser fabricated and arc-melted AlxCoCrFeNi high entropy alloys, Materials Science and Engineering: A, 633 (2015) 184-193.
[45] W.H. Liu, Z.P. Lu, J.Y. He, J.H. Luan, Z.J. Wang, B. Liu, Y. Liu, M.W. Chen, C.T. Liu, Ductile CoCrFeNiMox high entropy alloys strengthened by hard intermetallic phases, Acta Materialia, 116 (2016) 332-342.
[46] T. Borkar, B. Gwalani, D. Choudhuri, C.V. Mikler, C.J. Yannetta, X. Chen, R.V. Ramanujan, M.J. Styles, M.A. Gibson, R. Banerjee, A combinatorial assessment of AlxCrCuFeNi2 (0 < x < 1.5) complex concentrated alloys: Microstructure, microhardness, and magnetic properties, Acta Materialia, 116 (2016) 63-76.
[47] X.D. Xu, P. Liu, S. Guo, A. Hirata, T. Fujita, T.G. Nieh, C.T. Liu, M.W. Chen, Nanoscale phase separation in a fcc-based CoCrCuFeNiAl0.5 high-entropy alloy, Acta Materialia, 84 (2015) 145-152.
[48] E.J. Pickering, H.J. Stone, N.G. Jones, Fine-scale precipitation in the high-entropy alloy Al0.5CrFeCoNiCu, Materials Science and Engineering: A, 645 (2015) 65-71.
[49] N.G. Jones, K.A. Christofidou, H.J. Stone, Rapid precipitation in an Al0.5CrFeCoNiCu high entropy alloy, Materials Science and Technology, 31 (2015) 1171-1177.
[50] H.M. Daoud, A. Manzoni, R. Volkl, N. Wanderka, U. Glatzel, Microstructure and Tensile Behavior of Al8Co17Cr17Cu8Fe17Ni33 (at.%) High-Entropy Alloy, JOM, 65 (2013) 1805-1814.
[51] H. Daoud, A. Manzoni, N. Wanderka, U. Glatzel, High-Temperature Tensile Strength of Al10Co25Cr8Fe15Ni36Ti6 Compositionally Complex Alloy (High-Entropy Alloy), JOM, 67 (2015) 2271-2277.
[52] Special Metals Company.
http://www.specialmetals.com/documents/Inconel%20alloy%20617.pdf.
[53] Sandmeyer Steel Company.
http://www.sandmeyersteel.com/images/Alloy800H-800HT-APR2013.pdf.
[54] A.V. Kuznetsov, D.G. Shaysultnov, N.D. Stepanov, G.A. Salishchev, and O.N. Senkov, Tensile properties of an AlCrCuNiFeCo high-entropy alloy in as-cast and wrought conditions, Materials Science and Engineering A, 533 (2012) 107–118.
[55] J.Y. He, H. Wang, H.L. Huang, X.D. Xu, M.W. Chen, Y. Wu, X.J. Liu, T.G. Nieh, K. An, Z.P. Lu, A precipitation-hardened high-entropy alloy with outstanding tensile properties, Acta Materialia, 102 (2016) 187-196.
[56] J.Y. He, H. Wang, Y. Wu, X.J. Liu, H.H. Mao, T.G. Nieh, Z.P. Lu, Precipitation behavior and its effects on tensile properties of FeCoNiCr high-entropy alloys, Intermetallics, 79 (2016) 41-52.
[57] B. Gwalani, V. Soni, D. Choudhuri, M. Lee, J. Hwang, S. Nam, H. Ryu, S. Hong, R. Banerjee, Stability of ordered L12 and B2 precipitates in face centered cubic based high entropy alloys-Al0.3CoFeCrNi and Al0.3CuFeCrNi2, Scripta Materialia, 123 (2016) 130-134.
[58] S. Ochiai, Y. Oya, T. Suzuki, Alloying Behavior of Ni3Al, Ni3Ga, Ni3Si and Ni3Ge, Acta Metallurgica, 32 (1984) 289-298.
[59] Y. Mishima, S. Ochiai, T. Suzuki, Lattice-Parameters of Ni(Gamma), Ni3Al (Gamma') and Ni3Ga (Gamma') Solid-Solutions with Additions of Transition and B-Subgroup Elements, Acta Metallurgica, 33 (1985) 1161-1169.
[60] A.J. Bradley, A. Taylor, An X-Ray Analysis of the Nickel-Aluminium System, Proceedings of the Royal Society of London A, 159 (1937) 56-72.
[61] A. Taylor, R.W. Floyd, The Constitution of Nickel-Rich Alloys of the Nickel Chromium Titanium System, Journal of the Institute of Metals, 80 (1952) 577.
[62] R.W. Guard, J.H. Westbrook, Alloying Behavior of Ni3Al (Gamma-Phase), Transactions of the American Institute of Mining and Metallurgical Engineers, 215 (1959) 807-814.
[63] K. Aoki, O. Izumi, Relation between Defect Hardening and Substitutional Solid-Solution Hardening in an Intermetallic Compound Ni3Al, Physica Status Solidi A, 38 (1976) 587-594.
[64] P.V.M. Rao, K.S. Murthy, S.V. Suryanarayana, S.V.N. Naidu, Effect of Ternary Additions on the Room-Temperature Lattice-Parameter of Ni3Al, Physica Status Solidi A, 133 (1992) 231-235.
[65] A.C. Yeh, K.C. Yang, J.W. Yeh, C.M. Kuo, Developing an advanced Si-bearing DS Ni-base superalloy, Journal of Alloys and Compounds, 585 (2014) 614-621.
[66] Y. Amouyal, D.N. Seidman, An atom-probe tomographic study of freckle formation in a nickel-based superalloy, Acta Materialia, 59 (2011) 6729-6742.
[67] R.C. Reed, A.C. Yeh, S. Tin, S.S. Babu, M.K. Miller, Identification of the partitioning characteristics of ruthenium in single crystal superalloys using atom probe tomography, Scripta Materialia, 51 (2004) 327-331.
[68] R.W. Cahn, P.A. Siemers, J.E. Geiger, P. Bardhan, The Order-Disorder Transformation in Ni3Al and Ni3Al-Fe Alloys - 1. Determination of the Transition-Temperatures and Their Relation to Ductility, Acta Metallurgica, 35 (1987) 2737-2751.
[69] F.J. Bremer, M. Beyss, H. Wenzl, The Order-Disorder Transition of the Intermetallic Phase Ni3Al, Physica Status Solidi A, 110 (1988) 77-82.
[70] T.T. Shun, C.H. Hung, C.F. Lee, Formation of ordered/disordered nanoparticles in FCC high entropy alloys, Journal of Alloys and Compounds, 493 (2010) 105-109.
[71] A. Takeuchi, A. Inoue, Classification of bulk metallic glasses by atomic size difference, heat of mixing and period of constituent elements and its application to characterization of the main alloying element, Materials Transactions, 46 (2005) 2817-2829.
[72] N. Saunders, Z. Guo, X. Li, A.P. Miodownik, J.P. Schille, Using JMatPro to model materials properties and behavior, JOM, 55 (2003) 60-65.
[73] S. Guo, Q. Hu, C. Ng, C.T. Liu, More than entropy in high-entropy alloys: Forming solid solutions or amorphous phase, Intermetallics, 41 (2013) 96-103.
[74] M. Chandran, S. Sondhi, First-principle calculation of APB energy in Ni-based binary and ternary alloys, Modelling and Simulation in Materials Science and Engineering, 19 (2011) 025008.
[75] Y.J. Chang, A.C. Yeh, The evolution of microstructures and high temperature properties of AlxCo1.5CrFeNi1.5Ti y high entropy alloys, Journal of Alloys and Compounds, 653 (2015) 379-385.
[76] J.M. Oblak, Owczarsk.Wa, Cellular Recrystallization in a Nickel-Base Superalloy, Transactions of the Metallurgical Society of AIME, 242 (1968) 1563.
[77] M. Veron, Y. Brechet, F. Louchet, Directional coarsening of Ni-based superalloys: Computer simulation at the mesoscopic level, Acta Materialia, 44 (1996) 3633-3641.
[78] M. Veron, Y. Brechet, F. Louchet, Directional coarsening of nickel based superalloys: Driving force and kinetics, Superalloys, (1996) 181-190.
[79] S. Neumeier, M. Dinkel, F. Pyczak, M. Goken, Nanoindentation and XRD investigations of single crystalline Ni-Ge brazed nickel-base superalloys PWA 1483 and Rene' N5, Materials Science and Engineering A, 528 (2011) 815-822.
[80] A.C. Yeh, S. Tin, Effects of Ru on the high-temperature phase stability of Ni-base single-crystal superalloys, Metallurgical and Materials Transactions A, 37A (2006) 2621-2631.
[81] T.K. Tsao, A.C. Yeh, The Thermal Stability and Strength of Highly Alloyed Ni3Al, Materials Transactions, 56 (2015) 1905-1910.
[82] J.C. Zhao, M. Larsen, V. Ravikumar, Phase precipitation and time-temperature-transformation diagram of Hastelloy X, Materials Science and Engineering A, 293 (2000) 112-119.
[83] J.C. Zhao, M.F. Henry, The thermodynamic prediction of phase stability in multicomponent superalloys, JOM, 54 (2002) 37-41.
[84] M.S.A. Karunaratne, C.M.F. Rae, R.C. Reed, On the microstructural instability of an experimental nickel-based single-crystal superalloy, Metallurgical and Materials Transactions A, 32 (2001) 2409-2421.
[85] M. Göken, M. Kempf, Microstructural properties of superalloys investigated by nanoindentations in an atomic force microscope, Acta Materialia, 47 (1999) 1043-1052.
[86] T. Schöberl, H. Gupta, P. Fratzl, Measurements of mechanical properties in Ni-base superalloys using nanoindentation and atomic force microscopy, Materials Science and Engineering: A, 363 (2003) 211-220.
[87] J.H. Oh, I.C. Choi, Y.J. Kim, B.G. Yoo, J.i. Jang, Variations in overall-and phase-hardness of a new Ni-based superalloy during isothermal aging, Materials Science and Engineering: A, 528 (2011) 6121-6127.
[88] W.C. Oliver, G.M. Pharr, An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments, Journal of Materials Research, 7 (1992) 1564-1583.
[89] H. Bibring, T. Khan, M. Rabinovitch, J. Stohr, Development and Evaluation of New Industrial DS Monocarbide Reinforced Composites for turbine Blades, Superalloys, 1976, pp. 331-340.
[90] C.T. Sims, N.S. Stoloff, W.C. Hagel, Superalloys II, Wiley-Interscience, United States, 1987.
[91] R. MacKay, T. Gabb, J. Smialek, M. Nathal, A new approach of designing superalloys for low density, JOM, 62 (2010) 48-54.
[92] http://www.metalprices.com/.
[93] G.A. Webster, C.P. Sullivan, Some Effects of Temperature Cycling on Creep Behaviour of a Nickel-Base Alloy, Journal of the Institute of Metals, 95 (1967) 138-142.
[94] R.A. Mackay, L.J. Ebert, The Development of Directional Coarsening of the Gamma'-Precipitate in Super-Alloy Single-Crystals, Scripta Metallurgica, 17 (1983) 1217-1222.
[95] T. Ichitsubo, D. Koumoto, M. Hirao, K. Tanaka, M. Osawa, T. Yokokawa, H. Harada, Rafting mechanism for Ni-base superalloy under external stress: elastic or elastic–plastic phenomena?, Acta materialia, 51 (2003) 4033-4044.
[96] T.K. Tsao, A.C. Yeh, C.M. Kuo, H. Murakami, On The Superior High Temperature Hardness of Precipitation Strengthened High Entropy Ni‐Based Alloys, Advanced Engineering Materials, (2016).
[97] D.H. Lee, M.Y. Seok, Y. Zhao, I.C. Choi, J. He, Z.P. Lu, J.Y. Suh, U. Ramamurty, M. Kawasaki, T.G. Langdon, J.I. Jang, Spherical nanoindentation creep behavior of nanocrystalline and coarse-grained CoCrFeMnNi high-entropy alloys, Acta Materialia, 109 (2016) 314-322.
[98] L. Zhang, P. Yu, H. Cheng, H. Zhang, H. Diao, Y. Shi, B. Chen, P. Chen, R. Feng, J. Bai, Nanoindentation Creep Behavior of an Al0.3CoCrFeNi High-Entropy Alloy, Metallurgical and Materials Transactions A, (2016) 1-5.
[99] D. Blavette, A. Bostel, Phase composition and long range order in γ′ phase of a nickel base single crystal superalloy CMSX2: An atom probe study, Acta Metallurgica, 32 (1984) 811-816.
[100] R. Völkl, U. Glatzel, M. Feller-Kniepmeier, Measurement of the lattice misfit in the single crystal nickel based superalloys CMSX-4, SRR99 and SC16 by convergent beam electron diffraction, Acta materialia, 46 (1998) 4395-4404.
[101] C.W. Tsai, M.H. Tsai, J.W. Yeh, C.C. Yang, Effect of temperature on mechanical properties of Al0.5CoCrCuFeNi wrought alloy, Journal of Alloys and Compounds, 490 (2010) 160-165.
[102] T. Khan, P. Caron, D. Fournier, K. Harris, Single Crystal Superalloys for Turbine Blades. Characterization and Optimization of CMSX-2 Alloy, Materials Technology, 73 (1985) 567-578.
[103] P. Gallagher, The influence of alloying, temperature, and related effects on the stacking fault energy, Metallurgical Transactions, 1 (1970) 2429-2461.
[104] M.A. Howes, Additional thermal fatigue data on nickel and cobalt-base superalloys, (1973).
[105] Y. Nakagawa, A. Ohtomo, Y. Saiga, Directional solidification of Rene' 80, Transactions of the Japan Institute of Metals, 17 (1976) 323-329.
[106] G. Hoppin III, M. Fujii, L. Sink, Development of low-cost directionally-solidified turbine blades, Superalloys, (1980) 225-234.
[107] U. Tetzlaff, H. Mughrabi, Enhancement of the high-temperature tensile creep strength of monocrystalline nickel-base superalloys by pre-rafting in compression, Superalloys, (2000) 273-282.
[108] H. Rouault-Rogez, M. Dupeux, M. Ignat, High temperature tensile creep of CMSX-2 nickel base superalloy single crystals, Acta Metallurgica et Materialia, 42 (1994) 3137-3148.
[109] F. R. N. Nabarro, Rafting in Superalloys, Metallurgical and Materials Transactions A, 27 (1996) 513-530.
[110] F.R.N. Nabarro, F. De Villiers, Physics of creep and creep-resistant alloys, CRC press, 1995.
[111] Y.K. Kim, D. Kim, H.K. Kim, C.S. Oh, B.J. Lee, An intermediate temperature creep model for Ni-based superalloys, International Journal of Plasticity, 79 (2016) 153-175.
[112] A. J. Zaddach, C. Niu, C. C. Koch and D. L. Irving, Mechanical Properties and Stacking Fault Energies of NiFeCrCoMn High-Entropy Alloy, JOM, 65 (2013) 1780-1789.
[113] S. Huang, W. Li, S. Lu, F.Y. Tian, J. Shen, E. Holmström and L. Vitos, Temperature dependent stacking fault energy of FeCrCoNiMn highentropy alloy, Sripta Materialia, 108 (2015) 44-47.
[114] T.M. Pollock, A.S. Argon, Creep Resistance of CMSX-3 Nickel-Base Superalloy Single-Crystals, Acta Metallurgica et Materialia, 40 (1992) 1-30.
[115] T.K. Tsao, A.C. Yeh, J.W. Yeh, M.S. Chiou, C.M. Kuo, H. Murakami, K. Kakehi, HIGH TEMPERATURE PROPERTIES OF ADVANCED DIRECTIONALLY-SOLIDIFIED HIGH ENTROPY SUPERALLOYS, Superalloys, (2016) 1001-1009.
[116] Y. Koizumi, T. Kobayashi, T. Yokokawa, J.X. Zhang, M. Osawa, H. Harada, Y. Aoki, M. Arai, Development of next-generation Ni-base single crystal superalloys, Superalloys, (2004) 35-43.
[117] K. Kawagishi, H. Harada, A. Sato, A. Sato, T. Kobayashi, The oxidation properties of fourth generation single-crystal nickel-based superalloys, JOM, 58 (2006) 43-46.
[118] A. Sato, Y.-L. Chiu, R. Reed, Oxidation of nickel-based single-crystal superalloys for industrial gas turbine applications, Acta Materialia, 59 (2011) 225-240.
[119] A. Evans, M. He, A. Suzuki, M. Gigliotti, B. Hazel, T. Pollock, A mechanism governing oxidation-assisted low-cycle fatigue of superalloys, Acta Materialia, 57 (2009) 2969-2983.
[120] D. Deb, S.R. Iyer, V. Radhakrishnan, A comparative study of oxidation and hot corrosion of a cast nickel base superalloy in different corrosive environments, Materials Letters, 29 (1996) 19-23.
[121] J. Tong, S. Dalby, J. Byrne, M. Henderson, M. Hardy, Creep, fatigue and oxidation in crack growth in advanced nickel base superalloys, International Journal of Fatigue, 23 (2001) 897-902.
[122] N. Eliaz, G. Shemesh, R. Latanision, Hot corrosion in gas turbine components, Engineering failure analysis, 9 (2002) 31-43.
[123] K. Harris, G. Erickson, R. Schwer, MAR-M247 derivations—CM247 LC DS alloy, CMSX single crystal alloys, properties and performance, Superalloys, (1984) 221-230.
[124] O. Cryosystems, Crystallographica Search-Match, Journal of Applied Crystallography, 32 (1999) 379-380.
[125] D. Das, V. Singh, S.V. Joshi, High temperature oxidation behaviour of directionally solidified nickel base superalloy CM–247LC, Materials science and technology, 19 (2003) 695-708.
[126] M.S. Chiou, S.R. Jian, A.C. Yeh, C.M. Kuo, Effects of Aluminum Addition on the High Temperature Oxidation Behavior of CM-247LC Ni-based Superalloy, International Journal of Electrochemical Science, 10 (2015) 5981-5993.
[127] S. Seal, S. Kuiry, L.A. Bracho, Studies on the surface chemistry of oxide films formed on IN-738LC superalloy at elevated temperatures in dry air, Oxidation of metals, 56 (2001) 583-603.
[128] M.J. Donachie, S.J. Donachie, Superalloys: a technical guide, ASM international, 2002.
[129] M. Li, X. Sun, T. Jin, H. Guan, Z. Hu, Oxidation Behavior of a Single-Crystal Ni-Base Superalloy in Air—II: At 1000, 1100, and 1150 °C, Oxidation of Metals, 60 (2003) 195-210.
[130] S. Kumar, D. Mudgal, S. Singh, S. Prakash, Cyclic oxidation behavior of bare and Cr3C2-25(NiCr) coated super alloy at elevated temperature, Advanced Materials Letters, 4 (2013) 754-761.
[131] L. Liu, S. Wu, Y. Dong, S. Lü, Effects of alloyed Mn on oxidation behaviour of a Co–Ni–Cr–Fe alloy between 1050 and 1250 °C, Corrosion Science, 104 (2016) 236-247.
[132] S. Bose, "High-Temperature Corrosion" In High Temperature Coatings, Butterworth-Heinemann: Burlington, 2007.
[133] N.S. BORNSTEIN, M.A. DeCRESCENTE, The role of sodium and sulfur in the accelerated oxidation phenomena-sulfidation, Corrosion, 26 (1970) 309-314.
[134] F. Pettit, G. Meier, M. Gell, C. Kartovich, R. Bricknel, W. Kent, J. Radovich, Oxidation and hot corrosion of superalloys, The Metal Society AIME, Warrendale, PA, 651 (1984).
[135] C.S. Giggins, F.S. Pettit, Oxidation of Ni-Cr-Al Alloys between 1000 Degrees and 1200 Degrees C, Journal of The Electrochemical Society, 118 (1971) 1782-1790.
[136] S.L. Chen, S. Daniel, F. Zhang, Y. Chang, X.Y. Yan, F.-Y. Xie, R. Schmid-Fetzer, W. Oates, The PANDAT software package and its applications, Calphad, 26 (2002) 175-188.
[137] F. Stott, G. Wood, J. Stringer, The influence of alloying elements on the development and maintenance of protective scales, Oxidation of metals, 44 (1995) 113-145.
[138] N. Birks, G. Meier, F. Pettit, Forming continuous alumina scales to protect superalloys, JOM, 46 (1994) 42-46.
[139] A.P. Gordon, M.D. Trexler, R.W. Neu, T.J. Sanders, D.L. McDowell, Corrosion kinetics of a directionally solidified Ni-base superalloy, Acta materialia, 55 (2007) 3375-3385.
[140] A.S. Suzuki, K. Kawagishi, T. Yokokawa, H. Harada, T. Kobayashi, A New Oxide Morphology Map: Initial Oxidation Behavior of Ni-Base Single-Crystal Superalloys, Metallurgical and Materials Transactions A, 43 (2012) 155-162.
[141] S. Mrowec, T. Werber, M. Zastawnik, The mechanism of high temperature sulphur corrosion of nickel-chromium alloys, Corrosion Science, 6 (1966) 47-68.
[142] R.A. Rapp, K. Goto, The hot corrosion of metals by molten salts, in: Proceedings of the Second International Symposium on Molten Salts, Physical Electrochemistry Division, Electrochemical Society, 1981, pp. 159.
[143] R.A. Rapp, Chemistry and electrochemistry of hot corrosion of metals, Materials Science and Engineering, 87 (1987) 319-327.
[144] A. Beltran, D. Shores, Superalloys, Wiley Interscience, New York, (1972) 317-339.
[145] M. Qiao, C. Zhou, Hot corrosion behavior of Co modified NiAl coating on nickel base superalloys, Corrosion Science, 63 (2012) 239-245.
[146] T.K. Tsao, A.C. Yeh, C.M. Kuo, H. Murakami, High Temperature Oxidation and Corrosion Properties of High Entropy Superalloys, Entropy, 18 (2016) 62.
[147] A. Sengupta, S. K. Putatunda, L. Bartosiewicz, J. Hangas, P. J. Nailos, M. Peputapeck, F. E. Alberts, Tensile behavior of a new single-crystal nickel-based superalloy (CMSX-4) at room and elevated temperatures, Journal of Materials Engineering and Performance, 3 (1994) 73-81.
[148] G. L. Erickson, THE DEVELOPMENT AND APPLICATION OF CMSX@-10, Superalloys, (1996) 35-44.