ABSTRACT Cu-Ge ferrite was prepared using the standard ceramic method. The creep rate of polycrystalline Cu1+xGexFe2-2xO4 ferrite has been measured as a function of time at room temperature. It is found that the indentation length increases with the increase of both time and applied load. A regime of individual creep curves is observed for the first and second stages. It is not possible to record the third stage of the curve as usually happened in an ordinary creep test, because fracture of the samples does not occur. The slope is found to increase with increasing germanium and copper content in the steady state region. The high value of n (stress exponent factor) indicates that the dislocation creep is the dominate mechanism. The porosity arrangements developed within the specimens were examined using optical microscope. The results are discussed with regard to models describing the role of the steady state creep rate of metals. The morphology of the samples shows that the porosity is increased by increasing both copper and germanium ions.
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nullH. Zaki, A. Abdel-Daiem, Y. Swilem, F. El-Tantawy, F. Al-Marzouki, A. Al-Ghamdi, S. Al-Heniti, F. Al-Hazmi and T. Al-harbi, "Indentation Creep Behavior and Microstructure of Cu-Ge Ferrites," Materials Sciences and Applications, Vol. 2 No. 8, 2011, pp. 1076-1082. doi: 10.4236/msa.2011.28145.
 T. Nishikawa, Y. Okamoto, T. Nakagawa, H. Kimura and H. Takeda, “Dislocation Climb-Controlled Creep of Polycrystalline Mn-Zn Ferrite,” Vol. 88, 1980, p. 538.
 T. Nishikawa and Y. Okamoto, “Creep Deformation of Polycrystalline Mn-Zn Ferrite Proceeding of the Third International Conference in Ferrite,” Center for Academic Publications, Japan, 1981, p. 306.
 F. R. N. Nabarro, “Deformation of Crystals by the Motion of Single Lonsin Report of a Conference on the Strength of Solids (Bristol, U.K.),” Physical Society, London, 1948, pp. 75-90.
 C. Herring, “Diffusional Viscoyity of a Polycrystalline Solid,” Journal of Applied Physics, Vol. 21, No. 5, 1950, pp. 437-445.
 R. L. Coble, “A Model for Boundary Diffusion Controlled Creep in Polycrystalline Materials,” Journal of Applied Physics, Vol. 34, No. 6, 1963, pp. 1679-1682.
 J. C. Harper and J. E. Dom, “Viscous Creep of Aluminum near Its Melting Temperature,” Acta Metallurgica, Vol. 5. No. 11, November 1957, pp. 654-665.
 F. H. Norton, “The Creep of Steel at High Temperature,” McGraw Hill, New York, 1929.
 S. -H. Song, J. Wu, X. J. Wei, D. Kumar, S. J. Liu and L. Q. Weng, “Creep preoperty evaluation 2.25 Cr-1Mo low alloy steel,” Material Science and Engineering A, Vol. 527, No. 9, 2010, pp. 2398.
 B. Wilshire and R. W. Evans, “Creep and Fracture of Engineering Materials and Structures,” Proceedings of Fifth International Conference, The Institute of Materials, 1993, pp. 812.
 A. Juhasz, P. Tasnadi and I. Kovacs, “Superplastic indentation creep of lead-tin eutectic,” Journal Material Science Letters, 1986, pp. 535-536.
 R. Roumina, B. Raeisinia and R. Mahmudi, “Room Tem-
perature Indentation Creep of Cast Pb-Sb Alloys,” Science Material, Vol. 51, 2004, pp. 497.
 M. Sternitzke and H. Hubner, “Creep Mechanisms Of Alumina/Sic Nanocomposites Ceramic Engineering and Science Proceedings,” Mrityunjay Singh & Todd Jessen, The American Ceramic Society, p. 145, 2001.
 A. R. Geranmayeh, R. Mahmudi, “Room-Temperature Indentation Creep of Lead Free Alloy,” Journal Electricity Material, 2005, Vol. 34, pp. 1002-1009.
 T. G. Langdon, “Identifying Creep Mechanisms at Low Stresses,” Material Science Engeneering, Vol. A283, 2000, pp. 266-273.
 B. Walser and O. D. Sherby, “Structure Dependence of Power Law Creep,” Scripta Metall, Vol. 16, No. 2, 1982, pp. 213-219. doi.10.1016/0036-9748(82)90389-1
 G. Sharma, R. V. Ramanujan, T. R. G. Kutty and G. P. Tiwari, “Hot Hardness and Indentation Creep Studies of a Fe-28Al-3Cr-0.2C Alloy,” Material Science Engeneering, Vol. A278, 2000, pp.106-112.
 C. Goetze and W. F. Brace, “Laboratory Observations of High-Temperature Rheology of Rocks,” Tectonophysics, Vol. 113, No. 1-4, 1972, pp. 583-600.
 D. L. Kohlstedt and C. Goetze, “Low-Stress
High-Temperature Creep in Olivine Single Crystals,” Journal Geophysial Research, Vol. 79, 1974, p. 2045.
 M. Kagiarova, W. Z. Barbara, Y. Shollock, Y. A. Boccaccini and J. Dusza, “Microstructure and Creep Behavior of a Si3N4-SiC Micronanocomposite,” Journal American Ceramic Society, Vol. 92, No. 2, 2009, pp. 439-444.
 W. D. Kingery, H. K. Bowen and D. R. Uhimann, “Introduction to Ceramic Science,” Wiley, New York, 1975, p. 474.
 J. Smith, “Magnetic properties of materials,” McGraw Hill, New York, 1971.
 D. M. Hemeda and O. M. Hemeda, “Electrical, Structural, Magnetic and Transport Properties of Zn2BaFe16O27 Doped with Cu2+,” Journal Magnetism Magnetic Matterials, Vol. 320, No. 8, 2008, pp.1557-1562.
 D. M. Hemeda and O. M. Hemeda, “Electrical, Structural, Magnetic and Transport Properties of Zn2 BaFe16O27 Doped with Cu2+,” American Journal of Applied Sciences, Vol. 5, No. 4, 2008, pp. 289- 295.
 J. Eckelt, C. Bottger and J. Hesse, “AC Susceptibility in the Reentrant Spin-Glass System (Fe0.65Ni0.35)1-xMn,” Journal Magnetism Magnetic Matterials, Vol. 104, No. 3, 1992, pp.1665-1667. doi.10.1016/0304-8853(92)91502-K
 E. G. Visser, M. T. Johnson, P. J. V. D. Zaag, “Ferrites: Production,” International Flavour-6, Japan, 1992, p. 807.