Molecular dynamics simulations of cold welding of nanoporous amorphous alloys: effects of welding conditions and microstructures.

Nanoscale cold welding is a promising method in the bottom-up fabrication of nanodevices. Herein, cold welding mechanisms of CuZr nanoporous amorphous alloys (NPAAs) are investigated by molecular dynamics simulations, along with the mechanical properties of the welded products. Effects of welding conditions and microstructural parameters are considered.

Nanoindentation characteristics of nanocrystalline B2 CuZr shape memory alloy via large-scale atomistic simulation.

Nanoindentation tests are performed by molecular dynamics simulation to explore the mechanical properties of nanocrystalline B2 CuZr shape memory alloys with average grain sizes ranging from 6 to 18 nm. Some paramount aspects are monitored, including indentation force-depth curve, hardness, yield strength, and elastic recovery. The results demonstrate an inverse Hall-Petch effect, i.

Characterization of the deformation behaviors under uniaxial stress for bicontinuous nanoporous amorphous alloys.

In this paper, the deformation behaviors of CuZr bicontinuous nanoporous amorphous alloys (BNAMs) under uniaxial tension/compression are explored by molecular dynamics simulations. Scaling laws between mechanical properties and relative density are investigated. The results demonstrate that the bending deformation of the ligament is the main elastic deformation mechanism under tension.

Mechanical properties and clamping behaviors of snow crab claw.

The high-performing biomimetic behaviors of crustaceans are the optimal results of long-time wise adaption to their living environment. One outstanding prototype is crab claw, which has the combining advantages of lightweight and high strength. To promote relevant engineering applications, it is imperative to explore its mechanical behaviors and structural characteristics.

A dissolving and glucose-responsive insulin-releasing microneedle patch for type 1 diabetes therapy.

Diabetes and its complications have become crucial public health challenges worldwide. In this study, we aim to develop a dissolving and glucose-responsive insulin-releasing microneedle (MN) patch system, for minimally invasive and glucose-responsive insulin delivery for type 1 diabetes therapy. The MNs were composed of dissolving and biodegradable gelatin and starch materials, which encapsulated glucose-responsive insulin-releasing gold nanocluster (AuNC) nanocarriers.

Strengthening mechanisms of graphene in copper matrix nanocomposites: A molecular dynamics study.

To clarify the strengthening mechanism of coated/embedded graphene in metal matrix nanocomposites, nanoindentation responses of graphene-coated/embedded copper nanocomposites are investigated using molecular dynamics simulations, with the consideration of indentation force-displacement relation, stress distribution, evolution of microstructure and dislocation, and elastic recovery. Results show that two mechanisms, graphene layer bearing surface tensile stress disperses the contact stress and blocks the propagation of dislocations, contribute to the enhanced hardness and improved load bearing capacity, but one is often dominant for different nanocomposites. The former dominates in graphene-coated structure while the latter dominates in graphene-embedded structure, and the reinforcement is more obvious in the coated structure.

Nanoscale Assembly of Copper Bearing-Sleeve via Cold-Welding: A Molecular Dynamics Study.

A bearing is an important component in contemporary machinery and equipment, whose main function is to support the mechanical rotator, reduce the friction coefficient during its movement, and guarantee the turning accuracy. However, assembly of a nanoscale bearing and sleeve is a challenging process for micro-nano mechanical manufacturers. Hence, we show the cold-welding mechanism of a copper nanobearing-nanosleeve via molecular dynamic simulations.

Effects of Cold Rolling and Annealing Prior to Dealloying on the Microstructure of Nanoporous Gold.

The properties of nanoporous gold (NPG) were known to be dependent on the microstructure of NPG. In this study, the effects of cold rolling and annealing of the original AgAu alloy on the microstructure of NPG produced by dealloying under free corrosion condition were investigated. AgAu alloy samples were cold-rolled to different strain levels/thickness reductions up to 98% and annealed at 900 °C for 3 h before dealloying.

Molecular dynamics study on cold-welding of 3D nanoporous composite structures.

Nanoporous metals are a class of novel nanomaterials with potential applications in many fields. Herein, we demonstrate the cold-welding mechanism of nanoporous metals with various combinations using molecular dynamics simulations. This study shows that it is possible to cold-weld two nanoporous metals to form a novel composite material.

Nanoindentation Investigation of Temperature Effects on the Mechanical Properties of Nafion 117.

Operating temperature can be a limiting factor in reliable applications of Proton Exchange Membrane (PEM) fuel cells. Nanoindentation tests were performed on perfluorosulfonic acid (PFSA) membranes (Nafion 117) in order to study the influence of the temperature condition on their mechanical properties. The hardness and reduced modulus of Nafion 117 were measured within a certain temperature range, from 10 to 70 °C.

The Role of Computer Simulation in Nanoporous Metals-A Review.

Nanoporous metals (NPMs) have proven to be all-round candidates in versatile and diverse applications. In this decade, interest has grown in the fabrication, characterization and applications of these intriguing materials. Most existing reviews focus on the experimental and theoretical works rather than the numerical simulation.

Surface effects on the mechanical properties of nanoporous materials.

Using the theory of surface elasticity, we investigate the mechanical properties of nanoporous materials. The classical theory of porous materials is modified to account for surface effects, which become increasingly important as the characteristic sizes of microstructures shrink to nanometers. First, a refined Timoshenko beam model is presented to predict the effective elastic modulus of nanoporous materials.

A new wetting mechanism based upon triple contact line pinning.

The classical Wenzel and Cassie models fail to give a physical explanation of such phenomenon as the macroscopic contact angle actually being equal to the Young's contact angle if there is a spot (surface defect) inside the droplet. Here, we derive the expression of the macroscopic contact angle for this special substrate in use of the principle of least potential energy, and our analytical results are in good agreement with the experimental data. Our findings also suggest that it is the triple contact line (TCL) rather than the contact area that dominates the contact angle.

Correlation of the thermal and electrical conductivities of nanoporous gold.

We measured the thermal and electrical conductivities of nanoporous Au thin foils in the temperature range 93-300 K. Resulting from the nanoscale microstructure, the two types of conductivities are both temperature dependent and significantly lower than those of bulk Au. However, the corresponding Lorenz number is strikingly similar to that of bulk Au, indicating that the Wiedemann-Franz law holds perfectly well for nanoporous metals in this temperature range.