Ultrafine Ceramic Grains Embedded in Metallic Glass Matrix: Achieving Superior Wear Resistance via Increase in Both Hardness and Toughness

Abstract

As structural materials, crystalline or metallic glass materials have attracted scientific and practical interests. However, some mechanisms involving critical size and shear bands have adverse effects on their mechanical properties. Here, we counter these two effects by introducing a special structure with ultrafine ceramic grains (with a diameter of ∼2.0 nm) embedded into a metallic glass matrix, wherein the grains are mainly composed of a Ta-W-N solid solution structure in nature, surrounded by a W-based amorphous matrix that contains Ta and N atoms. Such a structure is in situ formed during preparation, which combines the merits of both phases to achieve simultaneous increase in hardness and toughness relative to references (pure TaN and W) and thus superior wear resistance. Even more remarkable, a favorable variation of increased hardness but reduced elasticity modulus can be induced by this structure. Intrinsically, ultrafine ceramic grains (free of dislocations), embedded in the metallic glass matrix, could prevent shear band propagation within the glass matrix and further improve the hardness of the matrix material. In return, such glass matrix allows for stiffness neutralization and structural relaxation to reduce the elasticity modulus of ceramic grains. This study will offer a new guidance to fabricate ultrahigh-performance metal-based composites.

Dual-Phase Nanocomposite TiB2/MoS1.7B0.3: An Excellent Ultralow Friction and Ultralow Wear Self-Lubricating Material

“…It forms very tightly intertwined and integrated networks, giving rise to a uniformly distributed dual-phase structure. The softer phase in such a composite structure is known to restrain the movement of dislocations in the grains of the stronger phase, thus improving the overall toughness via structural relaxation that promotes intrinsic crack self-consumption. , The resulting dense DPNC film has a very smooth surface that is highly conducive to reducing friction and wear; meanwhile, the finely intertwined dual-phase nanostructure effectively protects MoS 2 by limiting its exposure to environmental pollutants. Moreover, the tightly compacted nanostructure is optimally designed to regulate the orderly consumption and offer a long-lasting continuous supply of the lubricant via a friction-driven mechanism.…”

Enhanced micro/nano-tribological performance in partially crystallized 60NiTi film

“…In addition to high H/E, large recoverable strain is also reported as an important contributor to the improved tribological performance [16,28,45]. This is because that large recoverable strain is able to make the deformation spring back into its original state as much as possible when removing external stress.…”

“…Although the average COF and wear resistance of the partially crystallized film are not the best compared with the result in open literature [69], this work concludes an effective and simple method for increasing the hardness and especially H/E, i.e., embedding the crystalline phase into its amorphous counterpart to reduce the elastic modulus by Voigt model while increase the hardness by composite effect. In addition, introducing the second phase, such as nitride phase, that has higher hardness and elastic modulus than the matrix phase can also increase the hardness and H/E [16]. This is because that, although such the second phase can increase both hardness and elastic modulus, the increase in hardness is more significant than the increase in elastic modulus.…”

“…In recent years, several new materials with special structures to address this problem have been designed. Yang et al [16] achieved the favorable variation (i.e., increase in hardness and decrease in elastic modulus) by introducing a special structure with ultrafine ceramic grains embedded into a metallic glass matrix. Penkov et al [13] found that elastic modulus was reduced while hardness remained nearly unchanged by decreasing the cobalt thickness of a new functional coatings comprising periodically stacked nanolayers of amorphous carbon and cobalt.…”

Fabrication and characterization of graphene and carbon nanotube reinforced bioceramic nanocomposites

“…Furthermore, on the worn surface, The H/E were all increased and the values in nanocarbon reinforced composites were still higher than that of pure HA. According to Hooke's law, by reducing elasticity modulus, the material is able to sustain higher elastic deformation prior to a failure at a given load [181].…”