MAX Phases

The MAX Phases are layered, hexagonal carbides and nitrides have the general formula: Mn+1AXn, (MAX) where n = 1 to 3, M is an early transition metal, A is an A-group (mostly IIIA and IVA, or groups 13 and 14) element and X is either carbon and/or nitrogen.

A list of the MAX phases known to date, in both bulk and thin film form:[1]
211 Phases 312 Phases 413 Phases
Ti2CdC, Sc2InC, Ti2AlC, Ti2GaC, Ti2InC, Ti2TlC, V2AlC, V2GaC, Cr2GaC, Ti2AlN, Ti2GaN, Ti2InN, V2GaN, Cr2GaN, Ti2GeC, Ti2SnC, Ti2PbC, V2GeC, Cr2AlC, Cr2GeC, V2PC, V2AsC, Ti2SC, Zr2InC, Zr2TlC, Nb2AlC, Nb2GaC, Nb2InC, Mo2GaC, Zr2InN, Zr2TlN, Zr2SnC, Zr2PbC, Nb2SnC, Nb2PC, Nb2AsC, Zr2SC, Nb2SC, Hf2InC, Hf2TlC, Ta2AlC, Ta2GaC, Hf2SnC, Hf2PbC, Hf2SnN, Hf2SC Ti3AlC2,

V3AlC2,
Ti3SiC2,
Ti3GeC2,
Ti3SnC2,
Ta3AlC2,

 Ti4AlN3,

V4AlC3,
Ti4GaC3,
Ti4SiC3,
Ti4GeC3,
Nb4AlC3,
Ta4AlC3,

Contents

History

In the 1990s, the ternary compound, Ti3SiC2, was synthesized and fully characterized for the first time by a research group in the Materials Engineering department at Drexel University. A year later they showed that this compound was but one of over sixty phases,[2] most discovered and produced in powder form in the sixties by H. Nowotny and coworkers.[3] In 1999 they discovered Ti4AlN3 and realized that they were dealing with a much larger family of solids that all behaved similarly. Since 1996, when the first paper was published on the subject, tremendous progress has been made in understanding the properties of these phases and the 1996 article [4] has been cited over 650 times.[5]

Properties

These carbides and nitrides possess unusual and, sometimes, unique chemical, physical, electrical, and mechanical properties that combine the best attributes of metals and ceramics.[6][7][8][9]

Electrical

The MAX phases are electrically and thermally conductive due to their metallic-like nature of bonding. Most of the MAX phases are better electric and thermal conductors than Ti.

Physical

While MAX phases are stiff, they can be machined as easily as metals. They can all be machined using a manual hacksaw, despite the fact that some of them are three times as stiff as titanium metal, with the same density as titanium. They can also be polished to a metallic luster because of their excellent electrical conductivities. They are not susceptible to thermal shock and exceptionally damage tolerant. Some are oxidation and corrosion resistant.

Mechanical

The MAX phases as a class are generally stiff, lightweight, and plastic at high temperatures. Some, like Ti3SiC2 and Ti2AlC, are also creep [10] and fatigue [11] resistant, and maintain their strengths to high temperatures. They exhibit unique deformation characterized by basal slip, a combination of kink and shear band deformation, and delaminations of individual grains.[12][13] During mechanical testing, it has been found that polycrystalline Ti3SiC2 cylinders can be repeatedly compressed at room temperature, up to stresses of 1 GPa, and fully recover upon the removal of the load while dissipating 25% of the energy. It was by characterizing these unique mechanical properties of the MAX phases that kinking non-linear solids and incipient kink bands (the micromechanism that is responsible for them) were discovered.

Potential Applications

Elements in differents shapes ,High temperature stable refractory material ,Coatings for electrical contacts ,Corrosion resistance at high temperature ,Corrosion resistance in corrosive chemical environments

References

  1. ^ Eklund, P., Beckers, M., Jansson, U., Högberg, H., & Hultman, L., The Mn+1AXn phases: Materials science and thin-film processing. Thin Solid Films 518, 1851-1878 (2010)
  2. ^ Barsoum, M.W., Brodkin, D., & El-Raghy, T., Layered Machinable Ceramics For High Temperature Applications. Scrip. Met. et. Mater. 36, 535-541 (1997)
  3. ^ Nowotny, H., Struktuchemie Einiger Verbindungen der Ubergangsmetalle mit den elementen C, Si, Ge, Sn. Prog. Solid State Chem. 2, 27 (1970)
  4. ^ Barsoum, M.W. & El-Raghy, T., Synthesis and Characterization of a Remarkable Ceramic: Ti3SiC2. J. Amer. Cer. Soc. 79 (7), 1953-1956 (1996)
  5. ^ Barsoum, M.W. & El-Raghy, T., Synthesis and Characterization of a Remarkable Ceramic: Ti3SiC2. J. Amer. Cer. Soc. 79 (7), 1953-1956 (1996)
  6. ^ Barsoum, M.W., The Mn+1AXn Phases: a New Class of Solids; Thermodynamically Stable Nanolaminates. Prog. Solid State Chem 28, 201-281 (2000)
  7. ^ Barsoum, M.W. Physical Properties of the MAX Phases in Encyclopedia of Materials Science and Technology, edited by K. H. J. Buschow et al. (Elsevier, Amsterdam, 2006)
  8. ^ Barsoum, M.W. & Radovic, M., 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)
  9. ^ Barsoum, M.W., The MAX Phases and Their Properties in Ceramics Science and Technology, Vol. 2: Properties,, edited by R. R. Riedel & I.-W. Chen (Wiley-VCH Verlag GmbH & Co, 2010), Vol. 2.
  10. ^ Radovic, M., Barsoum, M.W., El-Raghy, T., & Wiederhorn, S.M., Tensile Creep of Coarse-Grained (100-300 µm) Ti3SiC2 in the 1000-1200 °C Temperature Range. J. Alloys and Compds. 361, 299-312 (2003)
  11. ^ Gilbert, C.J. et al., Fatigue-crack Growth and Fracture Properties of Coarse and Finegrained Ti3SiC2. Scripa Materialia 238 (2), 761-767 (2000)
  12. ^ Barsoum, M.W. & El-Raghy, T., Room Temperature Ductile Carbides. Metallurgical and Materials Trans. 30A, 363-369 (1999).
  13. ^ Barsoum, M.W., Farber, L., El-Raghy, T., & Levin, I., Dislocations, Kink Bands and Room Temperature Plasticity of Ti3SiC2. Met. Mater. Trans. 30A, 1727-1738 (1999)

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