Abstract
It will be shown that there is an analogy between surfactants in liquids which stabilize structures with large surface areas such as foams or microemulsions, and certain components in a crystalline solid, which stabilize defects such as grain boundaries and dislocations. These components are then called defactants. In the presence of defactants microstructural changes may occur because some of the defects compete more successfully for segregation of the defactants than others. Thus voids are formed at grain boundaries of Cu – Bi alloys because the formation energy of voids is provided by the interaction energy of Bi-atoms of the newly created surface. Or the beneficial role of rhenium on the high temperature creep of superalloys may be interpreted as a deficiency of defactants stabilizing dislocations and/or vacancies. These examples are discussed in the present work after a general treatment of the role of defactants.
References
[1] J.W.Gibbs: Trans Conn Acad, 1876, vol. III, 108–248 and 1878, vol. III, 343. Also in “The collected work of J.W. Gibbs”, Vol. I, Longmans, Green and Co., New York 1928, p. 55.Search in Google Scholar
[2] J.W.Cahn, in: W.C.Johnson, J.M.Blakely (Eds.), Interfacial Segregation, ASM International, International Materials Park, OH 44073-0002, 1979, p. 3–23.Search in Google Scholar
[3] C.Wagner: Nachrichten der Akademie der Wissenschaften in Göttingen, II. Mathematisch-Physikalische Klasse3 (1973) 1.Search in Google Scholar
[4] R.Kirchheim: Acta Mater.55 (2007) 5129.10.1016/j.actamat.2007.05.047Search in Google Scholar
[5] R.Kirchheim: Acta Mater.55 (2007) 5139.10.1016/j.actamat.2007.05.033Search in Google Scholar
[6] B.A.Hills: J. Appl. Physiol.87 (1999) 1567.10.1152/jappl.1999.87.5.1567Search in Google Scholar
[7] H.Leitao, A.M.Somoza, M.M.Telo da Gama: J. Chem. Phys.105 (1996) 2875.Search in Google Scholar
[8] R.M.Pashley, M.E.Karaman: Applied Colloid and Surface Chemistry, Wiley, Ltd., New York (2004) p. 52.Search in Google Scholar
[9] R.Kirchheim: Acta Mater.50 (2002) 413.10.1016/S1359-6454(01)00338-XSearch in Google Scholar
[10] S.O.Nielsen, C.F.Lopez, P.B.Moore, J.C.Shelley, M.L. Klein; J. Phys. Chem. B107 (2003) 13911.10.1021/jp035262cSearch in Google Scholar
[11] I am grateful to Haili Wang from the Institute of Metals Research, Chinese Academy of Science, Shenyang, China for pointing my attention to this error.Search in Google Scholar
[12] Z.Łodziana, N-Y.Topsøe, J.K.Nørskov: Nature Materials3 (2004) 289.Search in Google Scholar
[13] Y.Fukai: Physica Scripta T103 (2003) 11.10.1238/Physica.Topical.103a00011Search in Google Scholar
[14] R.C.Reed RC: The superalloys: fundamentals and applications, Cambridge University Press (2006).10.1017/CBO9780511541285Search in Google Scholar
[15] T.M.Pollock, R.D.Field: Dislocations and high temperature plastic deformation of superalloy single crystals. Dislocations in solids, vol. 11. Amsterdam: Elsevier (2002).10.1016/S1572-4859(02)80014-6Search in Google Scholar
[16] P.G.Shewmon: Metall. Mater. Trans. A29 (1998) 1535.10.1007/s11661-998-0075-4Search in Google Scholar
[17] E.D.Hondros, D.McLean: Phil. Mag.29 (1974) 771.Search in Google Scholar
[18] D.Chatain, P.Wynblatt, G.S.Rohrer: Acta Mater.53 (2005) 4057.Search in Google Scholar
[19] G.Wolde-Georgis, T.Al-Kassab: Unpublished results.Search in Google Scholar
[20] U.Albert, H.Müllejans, M.Rühle: Acta Mater.47 (1999) 4047.Search in Google Scholar
[21] G.A.Lopez, W.Gust, E.J.Mittemeijer: Scripta Mater.49 (2003) 747.Search in Google Scholar
© 2009, Carl Hanser Verlag, München
