Seok-Woo Lee

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We report that defect-free Au nanowires show superplasticity on tensile deformation. Evidences from high-resolution electron microscopes indicated that the plastic deformation proceeds layer-by-layer in an atomically coherent fashion to a long distance. Furthermore, the stress-strain curve provides full interpretation of the deformation. After initial(More)
Emergence of film-thicknessand grain-size-dependent elastic properties in nanocrystalline thin films Jie Lian, Seok-Woo Lee, Lorenzo Valdevit, Michael I. Baskes and Julia R. Greera,⇑ Division of Engineering and Applied Sciences, California Institute of Technology, 1200 East California Boulevard, MC 309-81, Pasadena, CA 91125-8100, USA Department of(More)
We present a set of efficient numerical algorithms to accurately compute the forces on dislocations in free-standing thin films. We first present a spectral method for computing the image stress field of dislocations in an isotropic elastic half space and a free-standing thin film. The traction force on the free surface is decomposed into Fourier modes by a(More)
This paper presents a miniaturized magnetic induction sensor (MMIS), where geomagnetism and high rpm rotation of ammunition are used to detect the turn number of the ammunition for applications to small-caliber turn-counting fuzes. The MMIS, composed of cores and a coil, has a robust structure without moving parts to increase the shock survivability in a(More)
To harness "smaller is more ductile" behavior emergent at nanoscale and to proliferate it onto materials with macroscale dimensions, we produced hollow-tube Cu60Zr40 metallic glass nanolattices with the layer thicknesses of 120, 60, and 20 nm. They exhibit unique transitions in deformation mode with tube-wall thickness and temperature. Molecular dynamics(More)
Dislocation junctions and jogs in a free-standing FCC thin film have been studied using 3dimensional dislocation dynamics simulations. Due to the unconstrained motion of surface nodes and dislocation annihilation at the free surface, junctions and jogs are unstable except for some uncommon conditions. If the film thickness is thin enough for a significant(More)
The pathways by which dislocations, line defects within the lattice structure, overcome microstructural obstacles represent a key aspect in understanding the main mechanisms that control mechanical properties of ductile crystalline materials. While edge dislocations were believed to change their glide plane only by a slow, non-conservative, thermally(More)
Bulk metallic glasses (BMGs) and nanocrystalline metals (NMs) have been extensively investigated due to their superior strengths and elastic limits. Despite these excellent mechanical properties, low ductility at room temperature and poor microstructural stability at elevated temperatures often limit their practical applications. Thus, there is a need for a(More)
Modulus of resilience, the measure of a material's ability to store and release elastic strain energy, is critical for realizing advanced mechanical actuation technologies in micro/nanoelectromechanical systems. In general, engineering the modulus of resilience is difficult because it requires asymmetrically increasing yield strength and Young's modulus(More)