Carbon ion implantation into aluminium: Mechanical and tribological properties

Aluminium, carbide nucleation and growing kinetics is correlated to the mechanical properties (hardness and elastic modulus), and to the friction coefficients as a function of carbon ion implantation parameters on aluminium. The microstructure of the modified surface was studied by: a) Elastic Recoil Detection Analysis (ERDA), b) Grazing Incidence X-ray Diffraction analysis (GIXRD) and c) Raman spectroscopy. Hardness and elastic modulus profiles were measured by instrumented nanoindentation technique. Pin-on-disc technique in reciprocal scratch mode was employed to obtain the friction coefficient profile. For low carbon fluences (<= 2 x 10(17) C+ cm(-2)) small size (approximate to 4 nm) embedded Al4C3 precipitates were produced. Higher carbon fluences create an amorphous-like structure. Implantations performed at high substrate temperatures can produce big size precipitate (approximate to 40 nm). Surface hardness increases as a function of carbon fluence resulting in values !
of about 6 GPa (20 times Al bulk value). The hardening mechanisms are associated with dislocations to precipitates bowing and/or cutting processes. Implantation parameters ruled the mechanical properties. Tribological responses are more difficult to correlate to the ion implantations conditions. However, wear is reduced when highly disordered C-C cluster are present.