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Abstract: This paper investigated properties of dispersed phases in an Al94Mn2Be2Cu2 alloy using a microindentation hardness test. The focus was directed to the possible strengthening phases for aluminium alloys: an icosahedral quasicrystalline phase (i-phase), a hexagonal quasicrystalline approximant with a large unit cell (H-phase) and a ternary cubic Be4AlMn. A single grain μ-Al4Mn was also examined as a reference. The application of scanning electron microscopy and a focussed ion beam, significantly increased the reliability and reproducibility of the microindentation results. The i-phase was distinguished by the highest Vickers hardness and the highest fraction of elastic energy, while the elastic modulus was the highest for Be4AlMn, being close to that of pure Be. The striking resemblances of the indentation curves for the phases with cluster substructures: i-phase, H-phase and μ-Al4Mn, especially the presence of pop-ins, suggested related deformation mechanisms. [ABSTRACT FROM AUTHOR]

Abstract: An anode layer source is a special ion gun, which can be fed with carbon precursors like acetylene to deposit hard and highly defect-free hydrogenated diamond-like carbon films at room temperature. The present study focuses on the influence of the process parameters — discharge voltage, process pressure and acetylene flow — on structure and mechanical properties of the deposited films. Raman spectra show that an increased discharge voltage yields decreased structural disorder, i.e. a lower C–C sp3 hybridised fraction of carbon atoms in the films. By an elevation of the discharge voltage from 1 to 3 kV the full width at half maximum of the G-band decreases from 194±0.2 cm−1 to 183±0.7 cm−1. Films deposited at the lowest discharge voltage show in accordance to the spectroscopic data the highest nanohardness (36±1 GPa), stress (−2.34±0.2 GPa) and reduced elastic modulus (180±4 GPa). [Copyright &y& Elsevier]

Nanolaminate coatings (NLC) consisting of alternated CrN coupled with either cubic tungsten nitride (β-W 2 N) or molybdenum nitride (γ-Mo 2 N) were deposited on cold worked tool steel substrates using reactive DC reactive magnetron sputtering for improved mechanical and corrosion resistance. The CrN/γ-Mo 2 N and CrN/β-W 2 N nanolaminate systems were found to perform better than the corresponding single-layer systems, with both mechanical and electrochemical properties improving by decreasing the individual layer thickness from 100 to 5 nm. The CrN/β-W 2 N NLC combined the high hardness value of W 2 N with the low corrosion current of CrN. The CrN/γ-Mo 2 N NLC showed synergistic improvements consisting of both higher hardness and lower corrosion currents with respect to the constituent materials alone. The dependence of mechanical and corrosion properties on the bilayer period is discussed in terms of the grain size, residual stresses and texture of the constituent materials and the nanostructured character of the multilayer architecture. [Display omitted] • CrN/Mo 2 N and CrN/W 2 N nanolayered coatings are deposited via DC magnetron sputtering. • CrN/Mo 2 N show synergistic improvements of microhardness and corrosion resistance. • CrN/W 2 N combine the high microhardness of W 2 N and the low corrosion current of CrN. • Grain refinement is the main responsible for the improvement of coatings properties. [ABSTRACT FROM AUTHOR]