The nanohardness H of multilayer specimens TiC/VC @ Si and TiC/VC @ Sapphire prepared by Pulsed-Laser-Deposition is investigated to check the existence of a superlattice effect as known from TiN/VN multilayers. In the present work the multilayer period thickness λ varies between 1.34 nm and 24.8 nm (total layer thickness t ≈ 200 nm). Unlike Young’s modulus E , H is enhanced, regardless of t , by covering Si as well as sapphire with a TiC/VC multilayer; the relative load carrying capacity being larger for Si. The maximum value of H obtained is 38 GPa for TiC/VC @ Sapphire. It is observed for a multilayer thickness of λ ≈ 10 nm. Hardness of TiC/VC @ Sapphire obeys, after annealing, a Hall-Petch relation H = 35.25 + 6.945 λ –0.5 ( H in GPa und λ ≥ 10 nm). From orientation dependent X-ray absorption fine structure and X-ray reflection records, short-range order and layer geometry are derived. These analyses reveal a continuous approach of interatomic distances Ti-C and V-C for deceasing multilayer periods. High-resolution transmission electron microscopy shows that multilayers are nanostructured, i.e. , not only TiC/VC phase boundaries but also subgrains represent obstacles against plastic deformation. Dislocations play a major role as sources of internal stress and vehicles of plasticity.
KeywordsTiC/VC@Si or Sapphire MultilayersSuperlattice EffectX-Ray Absorption SpectrometryElectron Microscopy
A. F. Jankowski and T. Tsakalakos, “The Effect of Strain on the Elastic Constants of Noble Metals,” Journal of Physics F: Metal Physics, Vol. 15, No. 6, 1985, pp. 1279- 1292. doi:10.1088/0305-4608/15/6/013
W. D. Sproul, “Reactive Sputter Deposition of Polycrys- talline Nitride and Oxide Superlattice Coatings,” Surface and Coatings Technology, Vol. 86-87, 1996, pp. 170-176. doi:10.1016/S0257-8972(96)02977-5
S. A. Barnett, “Physics of Thin Films,” M. H. Francombe and J. L. Vossen, Eds., Vol. 17, Academic Press, San Diego, 1993.
L. Hultman, C. Engstr?m and M. Odén, “Mechanical and Thermal Stability of TiN/NbN Superlattice Thin Films,” Surface and Coatings Technology, Vol. 133-134, 2000, pp. 227-233. doi:10.1016/S0257-8972(00)00935-X
U. Helmersson, S. Todorova, S. A. Barnett, J.-E. Sundgren, L. C. Markert and J. E. Greene, “Growth of Single-Crys- tal TiN/VN Strained Layer Superlattices with Extremely High Mechanical Hardness,” Journal of Applied Physics, Vol. 62, No. 2, 1987, pp. 481-484. doi:10.1063/1.339770
J. S. Koehler, “Attempt to Design a Strong Solid,” Physi- cal Review B, Vol. 2, No. 2, 1970, pp. 547-551.
A. Misra, J. P. Hirth and R. G. Hoagland, “Length- Scale-Dependent Deformation Mechanisms in Incoherent Metallic Multi-layered Composites,” Acta Materialia, Vol. 53, No. 18, 2005, pp. 4817-4824. doi:10.1016/j.actamat.2005.06.025
H. Ljungcrantz, C. Engstr?m, L. Hultman, M. Olsson, X. Chu, M. S. Wong and W. D. Sproul, “Nanoindentation Hardness, Abrasive Wear, and Microstructure of TiN/NbN Polycrystalline Nanostructured Multilayer Films by Re- active Magnetron Sputtering,” Journal of Vacuum Sci- ence and Technology A, Vol. 16, No. 5, 1998, pp. 3104- 3113.
G. Abadias, A. Michel, C. Tromas, C. Jaouen and S. N. Dub, “Stress, Interfacial Effects and Mechanical Proper- ties of Nanoscale Multilayered Coatings,” Surface and Coatings Technology, Vol. 202, No. 4-7, 2007, pp. 844- 853. doi:10.1016/j.surfcoat.2007.05.068
K. N. Strafford, “Tribological Properties of Coatings— Expectations, Performance and the Design Dilemma,” Surface and Coatings Technology, Vol. 81, No. 1, 1996, pp. 106-117. doi:10.1016/0257-8972(95)02651-7
A. R. Phani, J. E. Krzanowski and J. J. Nainaparampil, “Structural and Mechanical Properties of TiC and Ti-Si-C Films Deposited by Pulsed Laser Deposition,” Journal of Vacuum Science and Technology A, Vol. 19, No. 5, 2001, pp. 2252-2258. doi:10.1116/1.1382876
S. Garcia-Manyes, A. G. Güell, P. Gorostiza and F. Sanz, “Nanomechanics of Silicon Surfaces with Atomic Force Microscopy: An Insight to the First Sates of Plastic De- formation,” Journal of Chemical Physics, Vol. 123, No. 11, 2005, pp. 114711-114717. doi:10.1063/1.2035094
S. Dub, V. Brazhkin, N. Novikov, G. Tolmachova, P. Litvin, L. Lityagina and T. Dyuzheva, “Comparative Studies of Mechanical Properties of Stishovite and Sap- phire Single Crystals by Nanoindentation,” Journal of Superhard Materials, Vol. 32, No. 6, 2010, pp. 406-414. doi:10.3103/S1063457610060067
P. Paufler and A. Belger, “Superhard Materials,” Proceed- ings of the 7th Vietnamese-German Seminar on Physics and Engineering, 28 March-3 April 2004, Halong Viet- nam, pp. 25-28.
J. Tang, J. S. Zabinski and J. E. Bultman, “TiC Coatings Prepared by Pulsed Laser Deposition and Magnetron Sputtering,” Surface and Coatings Technology, Vol. 91, No. 1, 1997, pp. 69-73. doi:10.1016/S0257-8972(96)03124-6
D. C. Meyer and P. Paufler, “X-Ray Characterization of Nanolayers,” H. S. Nalwa, Ed., Encyclopedia of Nanosci- ence and Nanotechnology, Vol. 10, No. 1, 2004, pp. 655- 680.
A. A. Levin, P. Paufler and D. C. Meyer, “Low-Tem- perature Domain Behaviour of a SrTiO3 (001) Single Crystal Plate,” Physica B, Vol. 393, No. 1-2, 2007, pp. 373-381. doi:10.1016/j.physb.2007.01.029
K. Helming, “Personal Communication”.
K. Helming and U. Preckwinkel, “Texture Analysis with Area Detectors,” Solid State Phenomena, Vol. 105, 2005, pp. 71-76. doi:10.4028/www.scientific.net/SSP.105.71
A. Belger, T. Sebald, P. Paufler, H. Mai and E. Beyer, “Polarized EXAFS Studies of TiC/VC-Multilayers,” HASYLAB Annual Report, Part 1, 2001, pp. 783-784.
N. K. Mukhopadhyay and P. Paufler, “Micro- and Nanoindentation Techniques for Mechanical Characteri- sation of Materials,” International Materials Reviews, Vol. 51, No. 4, 2006, pp. 209-245. doi:10.1179/174328006X102475
I. P. Shakhverdova, P. Paufler, R. S. Bubnova, S. K. Fila- tov, A. A. Levin and D. C. Meyer, ”Mechanical Proper- ties of Single Crystalline and Glassy Lithium Triborate,” Crystal Research and Technology, Vol. 43, No. 4, 2008, pp. 339-349. doi:10.1002/crat.200711104
W. C. Oliver and G. M. Pharr, “An Improved Technique for Determining Hardness and Elastic Modulus Using Load and Displacement Sensing Indentation Experi- ments,” Journal of Materials Research, Vol. 7, No. 6, 1992, pp. 1564-1583. doi:10.1557/JMR.1992.1564
E. Meyer, “Untersuchungen über H?rteprüfung und H?rte,” Zeitschrift des Vereins Deutscher Ingenieure, Vol. 52, No. 17, 1908, pp. 645-654, 740-748, 835-844.
“Elastica,” Software Package, Version 2.1. Asmec Ger- many, 2003. www.asmec.de
A. M. Korsunsky, M. R. McGurk, S. J. Bull and T. F. Page, “On the Hardness of Coated Systems,” Surface and CoatingsTechnology, Vol. 99, No. 1, 1998, pp. 171-183. doi:10.1016/S0257-8972(97)00522-7
E. O. Hall, “The Deformation and Ageing of Mild Steel. III Discussion of Results,” Proceedings of the Physical Society London, Vol. 64, No. 381, 1951, pp. 747-753.
N. J. Petch, “The Cleavage Strength of Polycrystals,” Journal of the Iron and Steel Institute, Vol. 174, 1953, pp. 25-28.
T. H. Courtney, “Mechanical Behavior of Materials,” McGraw Hill Publ. Co., Singapore, 1990.
J. C. M. Li, “Petch Relation and Grain Boundary Sources,” Transactions of the Metallurgical Society of AIME, Vol. 227, 1963, pp. 239-247.
P. Kizler and S. Schmauder, “Simulation of the Nanoin- dentation of Hard Metal Carbide Layer Systems—The Case of Nanostructured Ultra-Hard Carbide Layer Sys- tems,” Computational Materials Science, Vol. 39, 2007, pp. 205-213. doi:10.1016/j.commatsci.2006.03.027
D. K. Chatterjee, M. G. Mendiratta and H. A. Lipsitt, “Deformation Behaviour of Single Crystals of Titanium Carbide,” Journal of Materials Science, Vol. 14, No. 9, 1979, pp. 2151-2156. doi:10.1007/BF00688420