We report transmission electron microscope observations that provide evidence of deformation twinning in plastically deformed nanocrystalline aluminum. The presence of these twins is directly related to the nanocrystalline structure, because they are not observed in coarse-grained pure aluminum. We propose a dislocation-based model to explain the preference for deformation twins and stacking fa...

Dislocation structures developed in hinge-type plastic zones associated with cracks in silicon crystals have been studied using a high voltage electron microscope (HVEM). Fine slip bands due to those dislocations have been also examined by an atomic force microscope (AFM). {100} and {110} cracks were introduced into {110} silicon wafers at room temperature by Vickers indentation method. The tem...

The anisotropic microstructure of bone tissue is crucial for appropriate mechanical and biological functions of bone. We recently revealed that the construction of oriented bone matrix is established by osteoblast alignment; there is a quite unique correlation between cell alignment and cell-produced bone matrix orientation governed by the molecular interactions between material surface and cel...

We develop a first-principles model of thermally activated cross-slip in magnesium in the presence of a random solute distribution. Electronic structure methods provide data for the interaction of solutes with prismatic dislocation cores and basal dislocation cores. Direct calculations of interaction energies are possible for solutes – K, Na and Sc – that lower the Mg prismatic stacking fault e...

Abstract Coarse-grained descriptions of dislocation motion in crystalline metals inherently represent a loss information regarding dislocation-dislocation interactions. In the present work, we consider coarse-graining framework capable re-capturing these interactions by means correlation functions. The depends on convolution length to define slip-system-specific densities. Following statistical...

Silicon in single crystal form has been the material of choice for the first demonstration of the MIT microengine project. However, because it has a relatively low melting temperature, silicon is not an ideal material for the intended operational environment of high temperature and stress. In addition, preliminary work indicates that single crystal silicon has a tendency to undergo localized de...

BACKGROUND For a full understanding of the mechanical properties of a material, it is essential to understand the defect structures and associated properties and microhardness indentation is a technique that can aid this understanding. RESULTS The Vickers hardness on (010), {011} and {110} faces lay in the range of 304-363 MPa. The Knoop Hardnesses on the same faces lay in the range 314-482 M...

PURPOSE Treatment of slipped capital femoral epiphysis (SCFE), including the modified Dunn procedure, restores anatomy with significant risk for avascular necrosis (AVN), if performed in the setting of moderate to severe, stable SCFE. The Imhauser osteotomy has been shown to be an effective way to correct residual deformity without the risk of AVN. We sought to evaluate the effectiveness and sa...

the study area locates between an active fault system of north anatolian in turkey and active alborz and zagros mountain ranges in iran. the total shortening concluded from arabia-eurasia collision with a rate of 22 mm/year across the ne persia is partitioned  into  two  fault  systems,  right-lateral  strike slip  movements  in  the  turkish-iranian  plateau  like  north tabriz fault system an...