Synthesis and elastic and mechanical properties of Cr2GeC


Herein we report on the synthesis and characterization of Cr2GeC, a member of the so-called Mn+1AXn (MAX) phase family of layered machinable carbides and nitrides. Polycrystalline samples were synthesized by hot pressing pure Cr, Ge, and C powders at 1350 °C at ∼45 MPa for 6 h. No peaks other than those associated with Cr2GeC and Cr2O3, in the form of eskolaite, were observed in the x-ray diffraction spectra. The samples were readily machinable and fully dense. The steady-state Vickers hardness was 2.5 ± 0.1 GPa. The Young’s moduli measured in compression and by ultrasound were 200 ± 10 and 245 ± 3 GPa, respectively; the shear modulus and Poisson’s ratio deduced from the ultrasound results were 80 GPa and 0.29, respectively. The ultimate compressive strength for a ∼20 μm grain size sample was 770 ± 30 MPa. Samples compressively loaded from 300 to ∼570 MPa exhibited nonlinear, fully reversible, reproducible, closed hysteretic loops that dissipated ∼20% of the mechanical energy, a characteristic of the MAX phases, in particular, and kinking nonlinear elastic solids, in general. The energy dissipated is presumably due to the formation and annihilation of incipient kink bands. The critical resolved shear stress of the basal plane dislocations—estimated from our microscale model—is ∼22 MPa. The incipient kink band and reversible dislocation densities, at the maximum stress of 568 MPa, are estimated to be 1.2 × 10−2 μm−3 and 1.0 × 1010 cm−2, respectively.

This is a preview of subscription content, access via your institution.

FIG. 1
FIG. 2
FIG. 3
FIG. 4
FIG. 5
FIG. 6
FIG. 7
FIG. 8


  1. 1

    M.W. Barsoum T. El-Raghy: A progress report on Ti3SiC2, Ti3GeC2 and the H-phases, M2BX. J. Mater. Synth. Process. 5, 197 1997

    CAS  Google Scholar 

  2. 2

    M. Sundberg, G. Malmqvist, A. Magnusson T. El-Raghy: Alumina forming high temperature silicides and carbides. Ceram. Int. 30, 1899 2004

    CAS  Article  Google Scholar 

  3. 3

    M.W. Barsoum T. El-Raghy: Synthesis and characterization of a remarkable ceramic. Ti3SiC2. J. Am. Ceram. Soc. 79, 1953 1996

    CAS  Article  Google Scholar 

  4. 4

    M.W. Barsoum, D. Brodkin T. El-Raghy: Layered machinable ceramics for high temperature applications. Scr. Met. Mater. 36, 535 1997

    CAS  Article  Google Scholar 

  5. 5

    X.H. Wang Y.C. Zhou: Oxidation behavior of Ti3AlC2 at 1000–1400 °C in air. Corros. Sci. 45, 891 2003

    CAS  Article  Google Scholar 

  6. 6

    M.W. Barsoum, T. El-Raghy, C.J. Rawn, W.D. Porter, H. Wang, A. Payzant C. Hubbard: Thermal properties of Ti3SiC2. J. Phys. Chem. Solids 60, 429 1999

    CAS  Article  Google Scholar 

  7. 7

    I.M. Low, S.K. Lee, B. Lawn M.W. Barsoum: Contact damage accumulation in Ti3SiC2. J. Am. Ceram. Soc. 81, 225 1998

    CAS  Article  Google Scholar 

  8. 8

    T. El-Raghy, M.W. Barsoum, A. Zavaliangos S.R. Kalidindi: Processing and mechanical properties of Ti3SiC2: II, Effect of grain size and deformation temperature. J. Am. Ceram. Soc. 82, 2855 1999

    CAS  Article  Google Scholar 

  9. 9

    M.W. Barsoum T. El-Raghy: Room temperature ductile carbides. Metall. Mater. Trans. A 30, 363 1999

    Article  Google Scholar 

  10. 10

    M.W. Barsoum: The MN + 1AXN Phases: A new class of solids; thermodynamically stable nanolaminates. Prog. Solid State Chem. 28, 201 2000

    CAS  Article  Google Scholar 

  11. 11

    H. Nowotny: Struktuchemie Einiger Verbindungen der Ubergangsmetalle mit den elementen C, Si, Ge. Sn. Prog. Solid State Chem. 2, 27 1970

    Article  Google Scholar 

  12. 12

    W. Jeitschko, H. Nowotny F. Benesovsky: Kohlenstoffhaltige ternare Verbindungen (V–Ge–C, Nb–Ga–C, Ta–Ga–C, Ta–Ge–C, Cr–Ga–C und Cr–Ge–C). Monatsh. Chem. 94, 844 1963

    CAS  Article  Google Scholar 

  13. 13

    B. Manoun, S. Amini, S. Gupta, S.K. Saxena M.W. Barsoum: On the compression behavior of Cr2GeC and V2GeC up to quasi-hydrostatic pressures of 50 GPa. J. Phys. Condens. Matter 19, 456218 2007

    Article  Google Scholar 

  14. 14

    T.H.S. S. Amini, A. Ganguly, S. Gupta, W. Tambussi, S. Clipper, M.W. Barsoum, J.D. Hettinger S.E. Lofland: On the thermal expansion of select MAX phases by dilatometry and high temperature x-ray diffraction. Phys. Rev. B (submitted)

  15. 15

    S. Amini, M.W. Barsoum T. El-Raghy: Synthesis and mechanical properties of fully dense Ti2SC. J. Am. Ceram. Soc. 90, 3953 2007

    CAS  Google Scholar 

  16. 16

    M.W. Barsoum, T. Zhen, A. Zhou, S. Basu S.R. Kalidindi: Microscale modeling of kinking nonlinear elastic solids. Phys. Rev. B 71, 134101 2005

    Article  Google Scholar 

  17. 17

    A. Murugaiah, M.W. Barsoum, S.R. Kalidindi T. Zhen: Spherical nanoindentations in Ti3SiC2. J. Mater. Res. 19, 1139 2004

    CAS  Article  Google Scholar 

  18. 18

    M.W. Barsoum, T. Zhen, S.R. Kalidindi, M. Radovic A. Murugahiah: Fully reversible, dislocation-based compressive deformation of Ti3SiC2 to 1 GPa. Nat. Mater. 2, 107 2003

    CAS  Article  Google Scholar 

  19. 19

    E. Orowan: A type of plastic deformation new in metals. Nature 149, 463 1942

    Google Scholar 

  20. 20

    S. Basu, M.W. Barsoum S.R. Kalidindi: Sapphire: A kinking nonlinear elastic solid. J. Appl. Phys. 99, 063501 2006

    Article  Google Scholar 

  21. 21

    F.C. Frank A.N. Stroh: On the theory of kinking. Proc. Phys. Soc. 65, 811 1952

    Article  Google Scholar 

  22. 22

    A.G. Zhou, S. Basu M.W. Barsoum: Kinking nonlinear elasticity, damping and microyielding of hexagonal close-packed metals. Acta Mater. 56, 60 2008

    CAS  Article  Google Scholar 

  23. 23

    M.W. Barsoum M. Radovic: Mechanical Properties of the MAX Phases in Encyclopedia of Materials Science and Technology, edited by R.W. Cahn, K.H.J. Buschow, M.C. Flemings, E.J. Kramer, S. Mahajan, and P. Veyssiere, Elsevier Amsterdam 2004

    Google Scholar 

  24. 24

    D. Hull: Introduction to Dislocations, Pergamon Press Ltd. Oxford 1965

    Google Scholar 

  25. 25

    M. Fraczkiewicz, A.G. Zhou M.W. Barsoum: Mechanical damping in porous Ti3SiC2. Acta Mater. 54, 5261 2006

    CAS  Article  Google Scholar 

  26. 26

    A.G. Zhou, M.W. Barsoum, S. Basu, S.R. Kalidindi T. El-Raghy: Incipient and regular kink bands in dense and porous Ti2AlC. Acta Mater. 54, 1631 2006

    CAS  Article  Google Scholar 

  27. 27

    L.H. Ho-Duc, T. El-Raghy M.W. Barsoum: Synthesis and characterization of 0.3VfTiC–TiSiC2 and 0.3VfSiC Ti3SiC2 composites. J. Alloys Compd. 350, 303 2003

    CAS  Article  Google Scholar 

  28. 28

    S. Basu, A. Zhou M.W. Barsoum: Reversible dislocation motion under contact loading in LiNbO3 single crystal. J. Mater. Res. 23(5), 1334 2008

    CAS  Article  Google Scholar 

  29. 29

    A. Ganguly, T. Zhen M.W. Barsoum: Synthesis and mechanical properties of Ti3GeC2 and Ti3(SixGe1−x)C2 (x = 0.5, 0.75) solid solutions. J. Alloys Compd. 376, 287 2004

    CAS  Article  Google Scholar 

  30. 30

    T. El-Raghy, A. Zavaliangos, M.W. Barsoum S.R. Kalidindi: Damage mechanisms around hardness indentations in Ti3SiC2. J. Am. Ceram. Soc. 80, 513 1997

    CAS  Article  Google Scholar 

  31. 31

    M.W. Barsoum, M. Ali T. El-Raghy: Processing and characterization of Ti2AlC, Ti2AlCN and Ti2AlC0.5N0.5. Met. Mater. Trans. A 31, 1857 2000

    Article  Google Scholar 

  32. 32

    I. Salama, T. El-Raghy M.W. Barsoum: Synthesis and mechanical properties of Nb2AlC and (Ti, Nb)2AlC. J. Alloys Compd. 347, 271 2002

    Article  Google Scholar 

  33. 33

    P. Pampuch, J. Lis, L. Stobierski M. Tymkiewicz: Solid combustion synthesis of Ti3SiC2. J. Eur. Ceram. Soc. 5, 283 1989

    CAS  Article  Google Scholar 

  34. 34

    M.W. Barsoum, A. Murugaiah, S.R. Kalidindi Y. Gogotsi: Kink bands, nonlinear elasticity and nanoindentations in graphite. Carbon 42, 1435 2004

    CAS  Article  Google Scholar 

  35. 35

    M.W. Barsoum, A. Murugaiah, S.R. Kalidindi T. Zhen: Kinking nonlinear elastic solids, nanoindentations and geology. Phys. Rev. Lett. 92, 255508 2004

    CAS  Article  Google Scholar 

  36. 36

    M.W. Barsoum, L. Farber, T. El-Raghy I. Levin: Dislocations, kink bands and room temperature plasticity of Ti3SiC2. Met. Mater. Trans. A 30, 1727 1999

    Article  Google Scholar 

  37. 37

    M.W. Barsoum: Nanoindentations of Nanolayered or Kinking Nonlinear Elastic Solids CRC Press Boca Raton, FL 2006

    Google Scholar 

  38. 38

    A.G. Zhou: Kinking non-linear elastic solids: Theory and experiments. Ph.D. Thesis, Drexel University, Philadelphia, 2008

    Google Scholar 

Download references


This work was funded by NSF (DMR 0736218). We are also grateful to Dr. Miladin Radovic in Texas A&M University for carrying out some of the ultrasonic measurements.

Author information



Corresponding author

Correspondence to Shahram Amini.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Amini, S., Zhou, A., Gupta, S. et al. Synthesis and elastic and mechanical properties of Cr2GeC. Journal of Materials Research 23, 2157–2165 (2008).

Download citation