相关论文: Anomalous High Strain Rate Compressive Behavior of…
To study the size and strain rate dependency of copper polycrystalline microstructures, a multi-layered copper/Al$_2$O$_3$ thin film was deposited on a Si substrate using a hybrid deposition system (combining physical vapour and atomic…
Understanding the mechanical properties of metals at extreme conditions is essential for the advancement of miniaturized technologies. As dimensions decrease, materials will experience higher strain rates at the same applied velocities.…
The slip strength of individual slip systems at different strain rates will control the mechanical response and strongly influence the anisotropy of plastic deformation. In this work, the slip activity and strain rate sensitivity of the <a>…
With decreasing system sizes, the mechanical properties and dominant deformation mechanisms of metals change. For larger scales, bulk behavior is observed that is characterized by a preservation and significant increase of dislocation…
The deformation behavior of single crystal and nanocrystalline nickel were studied using in situ micropillar compression experiments from quasi-static to high strain rates up to 10^3 s-1. Deformation occurred by dislocation slip activity in…
Metals exhibit an upturn in strength at strain rates of approximately 1000 s-1 - 3000 s-1, governed by rapid dislocation multiplication, interactions and storage. This phenomenon is strongly influenced by the initial dislocation density…
Mechanical testing of micropillars is a field that involves new physics, as the behaviour of materials is non-deterministic at this scale. To better understand their deformation mechanisms we applied 3-dimensional high angular resolution…
It is now possible to create perfect crystal nanowires of many metals. The deformation of such objects requires a good understanding of the processes involved in plasticity at the nanoscale. Isotropic compression of such nanometre scale…
Molecular dynamics simulations on tensile deformation of initially defect free single crystal copper nanowire oriented in <001>{100} has been carried out at 10 K under adiabatic and isothermal loading conditions. The tensile behaviour was…
The study of the high strain rate mechanical behaviour of materials using micropillar compression tests has been hindered so far due to the lack of suitable instrumentation. In the present study, a novel high strain rate micropillar…
Plastic deformation of micron-scale crystalline materials differ considerably from bulk ones, because it is characterized by random strain bursts. To obtain a detailed picture about this stochastic phenomenon, micron sized pillars have been…
An equimolar NiCoFeCrGa high entropy alloy having dual-phase homogeneous components was studied, where the constituent phases exhibit distinct mechanical properties. Micropillars with various diameters were created from two differently heat…
(Abridged, full abstract available in the text) The main goal of the study presented in this thesis was to perform in-situ investigations on deformation structures in plastically deformed polycrystalline copper at low degrees (<5%) of…
Dislocation slip is a general deformation mode and governs the strength of metals. Via discrete dislocation dynamics and molecular dynamics simulations, we investigate the strain rate and dislocation density dependence of the strength of…
Tungsten carbide cobalt hardmetals are commonly used as cutting tools subject to high operation temperature and pressures, where the mechanical performance of the tungsten carbide phase affects the wear and lifetime of the material. In this…
Micron-scale single crystalline materials deform plastically via large intermittent strain bursts that make the deformation process unpredictable. Here we investigate this stochastic phenomenon by analysing the plastic response of an…
We report a novel experimental methodology for in situ measurement of electrical resistivity changes in T2 copper during dynamic compression utilizing a split Hopkinson pressure bar. The effects of adiabatic temperature rise and specimen…
Microcrystals deform very differently from their macroscopic counterparts, displaying a size-dependent yield stress and intermittent plastic strain bursts. Here we demonstrate that size effects and strain bursts may be just two different…
The microstructure and mechanical properties of materials saturate to steady states after severe plastic deformation (SPD). Despite the well-known effect of temperature on the steady-state microstructure, there is no general agreement on…
A clear understanding of the dynamic behavior of metals is critical for developing superior structural materials as well as for improving material processing techniques such as cold spray and shot peening. Using a high velocity (from 120…