다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

EMS-A software package for electron diffraction analysis and HREM image simulation in materials science

Overview of constitutive laws, kinematics, homogenization and multiscale methods in crystal plasticity finite-element modeling: Theory, experiments, applications

High angle boundaries formed by grain subdivision mechanisms

A special deformation technique, equal channel angular extrusion, (ECAE) to control materials structure, texture and physico-mechanical properties is described in detail. The paper presents a continual analysis of stress, strain, shear planes, steady and localized flow, multipass processing which define microstructural effects and are critical for attained results. Links between macromechanics of simple shear and grain refinement are outlined.

Equal channel angular extrusion: from macromechanics to structure formation

The microstructures of two representative high-palladium dental alloys, a Pd-Cu-Ga alloy and a Pd-Ga alloy, which had been subjected to cyclic fatigue in uniaxial tension were investigated by transmission electron microscopy (TEM) Two different mechanisms were found to dominate microplastic deformation during fatigue: twinning in the Pd-Cu-Ga alloy, and planar slip of dislocations in the Pd-Ga alloy In addition, stress-induced precipitation occurred in the Pd-Ga alloy during cyclic loading Heat treatment simulating the firing cycles for dental porcelain resulted in the formation of a previously unreported bcc phase in the Pd-Cu-Ga alloy, and in the elimination of the characteristic tweed structure found in the Pd-Ga alloy for the as-cast condition

Fatigue studies of high-palladium dental casting alloys: Part II. Transmission electron microscopic observations†

O-lattice analysis of fcc-bcc interfaces

The purpose of this paper is to describe the different grain boundary structures and kinds of dislocations which can arise in the {510} Σ13 grain boundary in diamond cubic materials. Firstly, the different possible grain boundary structures are derived within the framework of group theory, and then general expressions for the Burgers vectors of the grain boundary dislocations which separate these structures are obtained. These grain boundary dislocations are of three kinds: (1) perfect grain boundary dislocations (also called DSC dislocations), which do not change the grain boundary structure, (2) imperfect grain boundary dislocations, which relate different, but equivalent, grain boundary structures, and finally (3) partial dislocations, which separate two non-equivalent grain boundary structures. Transmission electron microscopy is then used to show that imperfect dislocations are indeed present in a Σ13 (22·6°/[001]½) grain boundary in Si, and have Burgers vectors consistent with ¼[001]½.

Grain boundary dislocations in a Σ13 grain boundary in silicon. I. Analysis of the possible grain boundary structures and dislocations

In a polycrystal of silicon, dissociated grain boundaries with orientations close to either the ∑=3{111}, ∑=3{112}, ∑=9{122} and ∑=27{255} coincident site lattices (CSL) were observed both optically and in the transmission electron microscope (TEM). Macroscopically ∑=3{111} and ∑=27{255} appeared stable whereas ∑=9{122} dissociated frequently into two ∑=3{111} boundaries. TEM observations revealed ∑=27{255} to dissociate into one or more triangular grains in several regions. These grains consisted of a ∑=3{111}, a ∑=9{122} and a ∑=9{111}/{115} boundary. The latter ∑=9 boundary dissociated further to form twin triangular grains. The driving forces for various dissociations are discussed.

William A.T. Clark

Papers

Fatigue studies of high-palladium dental casting alloys: Part II. Transmission electron microscopic observations†

O-lattice analysis of fcc-bcc interfaces

Grain boundary dislocations in a Σ13 grain boundary in silicon. I. Analysis of the possible grain boundary structures and dislocations

Observations of Dissociated High Angle Csl Boundaries in Silicon

Structure of interphase boundaries in a Eutectic Co-Al alloy