Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).

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Hallmarks of mechanochemistry: From nanoparticles to technology

3D printing of Aluminium alloys: Additive Manufacturing of Aluminium alloys using selective laser melting

A review on fundamental of high entropy alloys with promising high–temperature properties

Defect-interface interactions

A conductive element of a cable or a wire is formed of an improved aluminum-zirconium alloy. The aluminum-zirconium alloy further includes an inoculant. The aluminum-zirconium alloy exhibits excellent ultimate tensile strength values and resistance to heat. Bonding wires formed from an improved aluminum-zirconium alloy exhibiting certain ultimate tensile strength values, fatigue resistance and/or creep rates are also described. Methods of forming cables and wires are also further disclosed.

Cables and wires having conductive elements formed from improved aluminum-zirconium alloys

Microstructural development during solidification and subsequent aging, and the resulting creep resistance, of laser powder-bed fusion (LPBF) Al-3.6Mn-2.0Fe-1.8Si-0.9Zr (wt%) alloy has been investigated. A bimodal grain structure is observed within the melt pool, with the bottom (MPB) exhibiting ultrafine equiaxed grains (∼ 1 µm in diameter) and the top/center (MPT) displaying fine epitaxial grains (∼ 10 µm in diameter). It is demonstrated that primary α-Al(FeMn)Si precipitates act as nuclei for α-Al grains and cause grain refinement at the MPB, thus preventing solidification cracking during processing of this complex alloy via LPBF. The α-Al(FeMn)Si precipitates formed alongside α-Al during solidification extensively decorate grain boundaries and are distributed uniformly within grain interiors. The subsequent aging of the alloy forms densely distributed L12-Al3Zr nanoprecipitates in the α-Al matrix without coarsening the α-Al(FeMn)Si particles. The alloy exhibits outstanding compressive creep resistance in both diffusional and dislocation creep regimes, which is predominantly attributed to the large fraction (∼ 15 vol%) of fine, semi-coherent α-Al(FeMn)Si precipitates that limit the creep flow by restricting both grain-boundary sliding and dislocation motion. With a compressive threshold stress of ∼ 74 MPa for dislocation climb at 300 °C, this alloy greatly outperforms most creep-resistant Al alloys. 

Laser-melted Al-3.6Mn-2.0Fe-1.8Si-0.9Zr (wt%) alloy with outstanding creep resistance via formation of α-Al(FeMn)Si precipitates

Shock compression in nanocrystalline nickel is simulated over a range of pressures (10–80 GPa) and compared with experimental results. Laser compression carried out at Omega and Janus yields new information on the deformation mechanisms of nanocrystalline Ni. Although conventional deformation does not produce hardening, the extreme regime imparted by laser compression generates an increase in hardness, attributed to the residual dislocations observed in the structure by TEM. An analytical model is applied to predict the critical pressure for the onset of twinning in nanocrystalline nickel. The slip‐twinning transition pressure is shifted from 20 GPa, for polycrystalline Ni, to 80 GPa, for Ni with g. s. of 10 nm. Contributions to the net strain from the different mechanisms of plastic deformation (partials, perfect dislocations, twinning, and grain boundary shear) were quantified in the nanocrystalline samples through MD calculations. The effect of release, a phenomenon often neglected in MD simulations, o...

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Laser compression of nanocrystalline metals

5000 series aluminum wrought alloys with high strength, high formability, excellent corrosion resistance, and friction-stir weldability, and methods of making those alloys.

High-performance 5000-series aluminum alloys and methods for making and using them

Improved 8000-series aluminum alloys exhibiting improved creep resistance and stress relaxation resistance are disclosed and are useful to form wires. The improved 8000-series aluminum alloys include a rare earth element. The electrical conductivity of the aluminum alloy is substantially unaffected by the addition of the rare earth element.

Nhon Q. Vo

Papers

Cables and wires having conductive elements formed from improved aluminum-zirconium alloys

Laser-melted Al-3.6Mn-2.0Fe-1.8Si-0.9Zr (wt%) alloy with outstanding creep resistance via formation of α-Al(FeMn)Si precipitates

Laser compression of nanocrystalline metals

High-performance 5000-series aluminum alloys and methods for making and using them

Wires formed from improved 8000-series aluminum alloy