Rev.Adv.Mater.Sci. (RAMS)
No 1/2, Vol. 50, 2017, pages 13-23

MICROSTRUCTURE AND MECHANICAL CHARACTERISTICS OF NANOSTRUCTURED
NICKEL-GRAPHENE COMPOSITES PROCESSED BY HIGH PRESSURE TORSION

I.Yu. Archakov, V.U. Kazykhanov, V.G. Konakov, O.Yu. Kurapova, A.E. Medvedev,
M.Yu. Murashkin, N.N. Novik, I.A. Ovid'ko, E.N. Solovyeva and R.Z. Valiev

Abstract

This paper presents data on fabrication of "nickel-graphene-graphite" bulk composites using powder metallurgy methods combined with the high energy ball milling. The composites were then processed by high pressure torsion (HPT) at temperatures of 23 and 200 úC. This treatment gives rise to the formation of new "nanostructured nickel-graphene" composites. The phase composition of the new composite specimens was examined by X-ray diffraction. Raman spectroscopy proved graphite-to-graphene conversion under mechanical treatments. The microstructure of the new composite specimens was investigated by scanning electron and transmission electron microscopy methods. Composite specimens after HPT at temperature of 200 úC demonstrate the optimal combination of strength (σ02= 923 MPa; σb= 992 MPa) and ductility (δ = 99%). Composite specimens with 2 wt.% graphene content after HPT at room temperature exhibits superior microhardness Hv = 6.45 GPa.

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