Nanocomposites and nanomaterials

Influence of the multiwall carbon nanotubes on properties of the Fe-Cu composites 
S. Revo1, S. Nedilko1, T. Avramenko1, K. Ivanenko1, P. Teselko1,                               M.C. Bouleklab2, S. Hamamda2, Y. Naoui2 
1Physics Faculty, Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Street, Kyiv-01601, Ukraine. 
E-mail: SNedilko@univ.kiev.ua.
2Laboratoire de thermodynamique et traitement de surfaces des matériaux, Université Frères Mentouri Constantine1, B.P. 325 Route, Ain El Bey, Constantine, 25017, Algérie

Fe-Cu nanoscale composite systems have attracted considerable attention for a long time, despite problems with their manufacturing. This interest is related with attractiveness of the Fe-Cu systems for many applications due to their well known high strength, thermal and electrical properties.
In this work dilatometric characteristics (relative expansion, ΔL/L0(T), and linear thermal expansion coefficient, CTE or α(T)), and calorimetric data of the Fe-Cu-CNT composite materials made by application of the mechano-chemical activation (concentration of multiwall carbon nanotubes CNT = 0, 0.5, 1.0 and 2.0 vol%, Fe : Cu ratio was 4:1) were studied and discussed together with data on the composition, structure and morphology of the samples. For this purpose the X-ray diffraction, Raman spectroscopy, IR absorption, optical and electron microscopy measurements were carried out. 
The results of the dilatometric and calorimetric characteristics study were analyzed in terms of the of multi-wall carbon nanotubes influence on the structure and morphology of the samples. Temperature changes of crystalline lattice constants; multivariant interaction of components; transformation of the lattice structure; phase transformation of components; reduction / shrinkage of the sample due to the temperature - activated release of adsorbed gases and gases of adsorbed compounds formed as a result of the thermal decomposition; sintering and, conversely, disintegration of grains and particles; as well as destruction of CNTs were discussed as possible mechanisms of thermal expansion of the studied composites.
The mechanisms of temperature and concentration CNTs influence are related to the change in composition and structure of composites and they were divided on two groups, such as "oxidation" and "carbidization".