Nanomechanical Properties and Deformation Behaviors of Multi-Component (AlCrTaTiZr)NxSiy High-Entropy Coatings

Abstract

Abstract:In this study multi-component (AlCrTaTiZr)N x Si y high-entropy coatings were developed by co-sputtering of AlCrTaTiZr alloy and Si in an Ar/N 2 mixed atmosphere with the application of different substrate biases and Si-target powers. Their nanomechanical properties and deformation behaviors were characterized by nanoindentation tests. Because of the effect of high mixing entropies, all the deposited multi-component (AlCrTaTiZr)N x Si y high-entropy coatings exhibited a simple face-centered cubic solid-solution structure. With an increased substrate bias and Si-target power, their microstructures changed from large columns with a [111] preferred orientation to a nanocomposite form with ultrafine grains. The hardness, H/E ratio and H 3 /E 2 ratio of (AlCrTaTiZr)N 1.07 Si 0.15 coating reached 30.2 GPa, 0.12 and 0.41 GPa, respectively, suggesting markedly suppressed dislocation activities and a very high resistance to wear and plastic deformation, attributable to grain refinements and film densification by the application of substrate bias, a nanocomposite structure by the introduction of silicon nitrides, and a strengthening effect induced by severe lattice distortions. In the deformed regions under indents, stacking faults or partial dislocations were formed, while in the stress-released regions, near-perfect lattices recovered.

Multi-component and high-entropy nitride coatings—A promising field in need of a novel approach

“…28 Several studies on multi-component nitride coatings have studied the variation of Si content in the materials. 56,[61][62][63] A secondary amorphous phase is indeed formed at high enough Si contents; see, e.g., Fig. 8 showing HRTEM images from Lin et al 63 However, it seems that the attained nanocomposite is more diffuse than the well-known ternary super-hard materials (e.g., nc-TiN/a-Si 3 N 4 ) and thus does not lead to the same hardening.…”

“…56,[61][62][63] A secondary amorphous phase is indeed formed at high enough Si contents; see, e.g., Fig. 8 showing HRTEM images from Lin et al 63 However, it seems that the attained nanocomposite is more diffuse than the well-known ternary super-hard materials (e.g., nc-TiN/a-Si 3 N 4 ) and thus does not lead to the same hardening. 62,63 It may be that such a distinct nanocomposite structure will prove to be elusive in multicomponent nitrides, as increased solubility in the metal nitride phase may prevent the formation of a distinct tissue phase.…”

“…8 showing HRTEM images from Lin et al 63 However, it seems that the attained nanocomposite is more diffuse than the well-known ternary super-hard materials (e.g., nc-TiN/a-Si 3 N 4 ) and thus does not lead to the same hardening. 62,63 It may be that such a distinct nanocomposite structure will prove to be elusive in multicomponent nitrides, as increased solubility in the metal nitride phase may prevent the formation of a distinct tissue phase. There is also a study by Lin et al 66 where carbon has been added to multicomponent nitrides, producing nanocomposite microstructures.…”

Microstructures and properties of high-entropy alloy films and coatings: a review

“…Surprisingly, based on the HRTEM observations, Cheng et al [174] and Lin [129] et al reported the formation of the nanocomposite structure in the (AlCr-TaTiZr)SiN coatings produced by the reactive RFmagnetron sputtering, and the hardness values of 34.5 and 30.2 GPa were obtained, respectively. The HRTEM images of the (AlCrTaTiZr)Si 0.15 N 1.07 coating were displayed in Figure 19 [129]. However, it can be seen that the nanocrystalline phase is elongated, rather than equiaxed, which is a typical feature of the nanocomposite films, as shown in Figure 14.…”

Effects of Silicon Content on the Microstructures and Mechanical Properties of (AlCrTiZrV)-Six-N High-Entropy Alloy Films

“…They attributed the extended solubility of Si to the high entropy effect. Lin et al [39] reported the formation of the nanocomposite structure in the (AlCrTaTiZr)SiN coatings produced by the reactive RF-magnetron sputtering, and found that the nanocrystalline phase is elongated, rather than equiaxed, which is a typical feature of the nanocomposite films. Moreover, the lattice can be observed within the denoted "amorphous regions", suggesting the probable crystallized feature in these regions.…”