Compressive deformation and failure of CrAlN/Si₃N₄ nanocomposite coatings

Abstract

The deformation and failure mechanisms of CrAlN/Si 3 N 4 coatings containing grains a few nanometres in size have been compared with those of conventional CrN-based coatings. It is shown that the addition of amorphous Si 3 N 4 phase increased the yield stress and hardness of the coating material, but did not change their ratio. This is consistent with theoretical predictions using existing models. However, cracking in conventional CrN-based coatings was catastrophic, whereas that in the fine-grained CrAlN/Si 3 N 4 structure was much more benign, suggesting that the improved performance of these materials is associated with their fracture behaviours.

Ultrastrong ductile and stable high-entropy alloys at small scales

“…31); CrAlN/Si 3 N 4 , ∼16 GPa (ref. 32) and Zn-based metallic glasses15, ∼2 GPa—and are in the same strength level of the defect-free Mo-alloy columns produced from etching NiAl–Mo eutectic compounds33 and about half of that of pure W whiskers34, still our HEA pillars exhibit much better ductility. Such HEA pillars also show a size-dependent strength, as presented by the relationship between the flow stress at 5% strain, σ 0.05 , versus the pillar diameter, D (Fig.…”

Deformation behavior of nanocrystalline titania particles accessed by complementary in situ electron microscopy techniques

“…15,84 Severe densification of a porous network might also rely on grain boundary mobility and/or diffusional processes to accommodate the imposed plastic deformation. 15,84 Severe densification of a porous network might also rely on grain boundary mobility and/or diffusional processes to accommodate the imposed plastic deformation.…”

Effects of indenter angle on micro‐scale fracture toughness measurement by pillar splitting

“…6,7 Lastly, the effects of the specimen microstructure such as the grain size distribution, the presence of secondary phases/precipitates, combined with the interface with the substrate further complicate the extraction of K c for thin films. 16 The single cantilever beam technique enables a measurement of the fracture toughness of the film material, while providing information about the adhesion as well. 6,7 In these techniques, a crack propagates from a notch in the micro-specimen until failure, and an analytical model is used to extract the fracture toughness.…”

“…6,7 The main testing geometries are single [12][13][14][15] and double cantilever beams. 16 This technique does not have issues related to the edge positioning, but the measurements can be affected by the geometry of the prenotch, the FIB current used to fabricate specimens, and the friction between the indenter and the specimen. [12][13][14] Jaya et al 15 successfully used this technique to extract the fracture toughness as a function of the temperature.…”