The charge-state-resolved ion energy distributions (IEDs) in filtered aluminum vacuum arc plasmas were measured and analyzed at different oxygen and argon pressures in the range 0.5 -8.0 mTorr. A significant reduction of the ion energy was detected as the pressure was increased, most pronounced in an argon environment and for the higher charge states. The corresponding average charge state decreased from 1.87 to 1.0 with increasing pressure. The IEDs of all metal ions in oxygen were fitted with shifted Maxwellian distributions. The results show that it is possible to obtain a plasma composition with a narrow chargestate distribution as well as a narrow IED. These data may enable tailoring thin-1 film properties through selecting growth conditions that are characterized by predefined charge state and energy distributions.2

Charge state resolved ion energy distribution functions (IEDFs) of Al+, Al2+ and Al3+ were measured as a function of Ar pressure in the range from 5.7 × 10−5 to 2.13 Pa (0.01 to 256 Pa cm). As the pressure distance product is increased, the annihilation of the Al2+ and Al3+ populations as well as the thermalization of the Al+ ion population is observed, resulting in the formation of a close to monoenergetic beam of Al+ ions at pressure distance product of 256 Pa cm. The average charge state was reduced from 1.58 to 1.00 as the pressure distance product was increased from 0.01 to 32 Pa cm. Thermalization is also observed in an Ar/O2 mixture at 128 Pa cm, where stoichiometric γ-alumina films are grown. The IEDFs have been fitted by a shifted Maxwellian distribution. The plasma processing strategy presented here resulting in a monoenergetic Al+ plasma beam may through substrate bias potential variations enable effective tailoring of thin film properties such as density, elasticity and phase stability.

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Thermal residual stresses (TRSs) in continuous Al2O3 fiber reinforced NiAl composites with and without a BN interlayer were studied by using the finite element method (FEM). The FEM model includes the effect of neighboring fibers of the composite. A minimum sample thickness and a minimum size of the surrounding composite have to be exceeded in order to obtain the correct TRS distribution in simulation. It is shown that the TRS, caused by different thermal expansion of fiber and matrix in the NiAl composite, is sufficiently large to cause fiber damage owing to twinning on different rhombohedral planes in the sapphire fiber. The introduction of a BN interlayer or a higher fiber volume fraction (40–60%) essentially reduces the TRS level in the NiAl composite and lessens the fiber damage. The residual stress in the NiAl composites was experimentally measured by nanoindentation. A good agreement between measurements and finite element analysis was achieved.

The high temperature stability of γ-Al2O3 films deposited using filtered cathodic arc and plasma assisted chemical vapor deposition on Ti0.33Al0.67N coated WC–Co cutting inserts is investigated. X-ray diffractometry reveals that filtered cathodic arc deposited films transform partially into the thermodynamically stable α-Al2O3 phase at a temperature of 1000°C. The γ to α-Al2O3 transformation for plasma assisted chemical vapor deposition grown films is observed at 900°C. These results are in qualitative agreement with differential scanning calorimetry measurements. Transmission electron microscopy on filtered cathodic arc and plasma assisted chemical vapor deposition films annealed at 900°C reveals the existence of hexagonal AlN in the Ti0.33Al0.67N interlayer, as well as Al depletion at the Al2O3/Ti0.33Al0.67N interface. After annealing the plasma assisted chemical vapor deposition sample at 900°C, α-Al2O3 grains with a size of ∼100 nm are observed inside the γ-Al2O3 matrix, while for filtered cathodic arc samples only the γ-phase is identified. Transmission electron microscopy analysis on both filtered cathodic arc and plasma assisted chemical vapor deposition samples annealed at 1000°C shows that the original Al2O3/Ti0.33Al0.67N/WC–Co layer architecture is no longer intact. The formation of TiO2 is detected along the growth direction of the Al2O3 films. The present study suggests that not only the morphology and the impurities incorporated into γ-Al2O3 but also stability of the Ti0.33Al0.67N interlayer determine the high temperature stability of γ-Al2O3/Ti0.33Al0.67N coated hardmetal.