相关论文: Complex strengthening mechanisms in nanocrystallin…
Strengthening by grain refinement via the Hall-Petch mechanism and softening by nanograin formation via the inverse Hall-Petch mechanism have been the subject of argument for decades, particularly for ultrafine-grained materials. In this…
We present atomistic simulations for the mechanical response of ultra nanocrystalline diamond, a polycrystalline form of diamond with grain diameters of the order of a few nm. We consider fully three-dimensional model structures, having…
In recent years it has become possible to study the properties of nanocrystalline metals through atomic-scale simulations of systems with realistic grain sizes. A brief overview of the main results is given, such as the observation of a…
Nanocrystalline metals, i.e. metals in which the grain size is in the nanometer range, have a range of technologically interesting properties including increased hardness and yield strength. We present atomic-scale simulations of the…
Incorporating the bond-order-length-strength correlation mechanism [Sun CQ, Prog Solid State Chem 35, 1 -159 (2007)] and Borns criterion for melting [J. Chem. Phys. 7, 591(1939)] into the conventional Hall-Petch relationship has turned out…
Nanoparticle reinforced alloys offer the potential of high strength, high temperature alloys. While promising, during rapid solidification processes, alloys suffer from nanoparticle clustering, which can discount any strength benefit. An…
The mechanical behavior of two nanocrystalline Al alloys, Al-Mg-Y and Al-Fe-Y, is investigated with in-situ micropillar compression testing. Both alloys were strengthened by a hierarchical microstructure including grain boundary…
Grain size engineering, particularly reducing grain size into the nanocrystalline regime, offers a promising pathway to further improve the strength-to-weight ratio of Al alloys. Unfortunately, the fabrication of nanocrystalline metals…
The mechanical performance and microstructures of a CoCrNi medium-entropy alloy (MEA) and NCoCrNi, alloyed with 0.5at% N, after high pressure torsion (HPT) and subsequent annealing treatments in a temperature range of 150-1000 {\deg}C were…
The strength, $\sigma_{\rm y}$, of a polycrystal decreases with mean grain diameter $D$ at $D\gtrsim50$ atoms (i.e. Hall-Petch behaviour) and increases at $D\lesssim50$ (i.e. inverse Hall-Petch behaviour). Our simulations generalise…
The mechanical properties of a material are intimately related to its microstructure. This is particularly important for predicting mechanical behavior of polycrystalline metals, where microstructural variations dictate the expected…
Stabilization of grain structure is important for nanocrystalline alloys, and grain boundary segregation is a common approach to restrict coarsening. Doping can alter grain boundary structure, with high temperature states such as amorphous…
Refractory multi-principal element alloys (MPEAs) have exceptional mechanical properties, including high strength-to-weight ratio and fracture toughness, at high temperatures. Here, we elucidate the complex interplay between segregation,…
Nanocrystalline metals contain a large fraction of high-energy grain boundaries, which may be considered as glassy phases. Consequently, with decreasing grain size, a crossover in the deformation behaviour of nanocrystals to that of…
The relationship between grain size and yield strength of metals follows the Hall-Petch relationship {\sigma} = {\sigma}0 + kd^-0.5; however, the specific physical factors that affect the coefficients {\sigma}0 and k of this relationship…
Solid solution effects on the strength of the finest nanocrystalline grain sizes are studied with molecular dynamics simulations of different Cu-based alloys. We find evidence of both solid solution strengthening and softening, with trends…
Hybrid Monte Carlo (MC)/molecular dynamics (MD) simulations are conducted to study the microstructures of nanocrystalline (nc) Cu/Ag alloys with various Ag concentrations. When the Ag concentration is below 50 Ag atoms/nm!, an increase in…
Minor alloying is widely used to control mechanical properties of metallic glasses (MGs). The present understanding of how a small amount of alloying element changes strength is that the additions lead to more efficient packing of atoms and…
Titanium-based shape memory alloys, such as Ti2448, have attracted enormous attention owing to their unique thermomechanical properties and potential biomedical applications. In this study, we develop a polycrystalline phase field to…
Mechanical alloying (MA) has been used to fabricate the Co2FeAl Heusler alloy with a nanocrystalline structure. The formation mechanism of the alloy has been investigated. Rietveld analysis showed that all samples that were milled for more…