Using notch geometry in the metallic glass (MG) samples, it is possible to improve the homogeneous plasticity and mechanical properties. In this work, the molecular dynamics (MD) simulation was performed to indicate how the alloying composition of MGs can tune the mechanical properties of notched samples. For this purpose, CuZr MGs were constructed through atomic-scale simulation with alloying compositions of Cu64Zr36, Cu60Zr40, Cu54Zr46, and Cu50Zr50, while a symmetrical surface notch was produced at the waistline of samples by removing certain atoms and relaxing the new free surfaces. The tensile loading was also carried out to characterize the plastic deformation and strength in the CuZr MGs. According to the results, Cu64Zr36 and Cu60Zr40 alloys exhibited a localized plastic deformation in the notch region, while the decrease in Cu content, i.e. Cu54Zr46, led to the generation of nanoscale shear events outside the notch region and extended the deformation area in the body of the sample. The results also indicated that the change in the mechanism of plastic deformation in the notched samples strongly depended on the type and population of polyhedrons rearranged in the backbone structure. Moreover, it was found that the Voronoi volume in the Cu54Zr46 alloy exhibited a gentle increment under the tensile loading in both the notched and un-notched regions, while the Cu-rich MGs, i.e. Cu64Zr36 and Cu60Zr40, showed a sudden increment of Voronoi volume at the center of the notch region, which was indicative of strain localization in the atomic system.
Versus the theory of fully stochastically mechanism of geomagnetic jerks based on the buoyant force driven Quasi-Geostrophic (QG) dynamo, the torsional waves in realistic condition of the Earth's core evolve in the intradecadal time scales. Geostrophic slow MC (& Rossby) waves as entanglement of inertial and Alfvén waves are the source of 6 & 9 year geomagnetic secular variations inferred with intradecadal variations in the Earth's rotation rate defined by length of day. From MHD equations in the Earth's liquid metal core, we find a suit of equations equivalent with Hall-MHD in plasma physics with variables and coefficients defined merely in the system of Earth's core dynamo. On reductive perturbation theory, it is deduced derivative nonlinear Schrödinger (DNLS) equation which describes torsional Alfvén waves. In nonlinearity, Modulational and decay instabilities of torsional Alfvén waves in the Earth's core maintain and control occurrences of the geomagnetic jerks and relevant LODs via perturbation theory. Instability induced from a small amplitude perturbation of the plane Alfvén wave can lead to an exponential growth or decay of nonlinear structures to maintain large amplitude turbulences, reasonable to produce the geomagnetic jerks and relevant LODs. Then interplanetary tiny electromagnetic inductions on the Earth's core dynamo via perturbation theory in nonlinearity can produce the jerks and relevant LODs. Also the first-order perturbation of 6-yr Alfvén wave for modulational instability yields to the localized wave-packets called Kuznetsov-Ma breather coincided to 14-yr periodicity for jerk's reports in the years 1902, 1916, 1930, 1944, 1958, 1972, 1986, 2000, 2014. We don't deny the random turbulences but we find that the random driven jerks have lower energies.
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