R.M. Wang
,
C.Z. Li
,
S. W. Zhang and M.G.Yan(1)Institute of Aeronautical Materials
,
Beijing 100095
,
China 2)Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China 3)Beijing Laboratory of Electron Microscopy
,
Chinese Academy of Sciences
,
Beijing 100080
,
China Manuscript received 26 August 1996)
金属学报(英文版)
The microstructures of the grain boundary phases in Fe-Ni-Co-Nb-Ti superalloy have been studied by high resolution electron microscopy (HREM).Besides the Laves phase,three other grain boundary phases have been found and analyzed. The ε phase particles are needle-like with some stacking faults along the(0001) direction. The dominant phase at the grain boundaries is the orthorhombic phase that is also rod-like. High reselution image also confirms the existence of the triclinic phase at the grain boundaries that is irregular and scarce.
关键词:
:high resolution electron microscopy
,
null
,
null
Scripta Materialia
An in situ ex-environmental transmission electron microscopy (TEM) study was carried out to investigate the oxidation behavior of RESn(3) (RE = Nd, La, Ce) film in a room at 18 +/- 2 degrees C with 20 +/- 5% humidity. The original RESn(3) compounds transformed into RE(OH)(3) nanocrystals and Sn clusters. This involved the selective oxidation of RE in RESn(3) and the atomic diffusion of Sn atoms. The whole oxidation behavior was discussed from the thermodynamic viewpoint, and a reaction formula was proposed to summarize the oxidation of RESn(3) under different ambient conditions. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
关键词:
RESn(3) compounds;Oxidation;Thermodynamics;Transmission electron;microscopy (TEM);pb-free solders;whisker growth;tin whiskers;surface;joints;alloys
Journal of Materials Science
High-resolution transmission electron microscopy images of stacking faults on (001) and (<(1)over bar 01>) planes in a beta-Si3N4 whisker were obtained and compared to image simulations. This procedure showed that the atomic structure of the four atomic planes around the (001) stacking fault plane in the beta-phase is very similar to that of the unit cell of alpha-Si3N4 crystal. The stacking fault was observed to climb under electron irradiation in the microscope.
关键词:
silicon-nitride;diffraction;composite;ceramics
Journal of Materials Research
Surface and planar defect structures of gamma-Al2O3, nanorods synthesized by the arc-discharge method were studied by means of high-resolution transmission electron microscopy and image simulation. Our investigation showed that there was a high number density of twins in the nanorods. We suggested a possible configuration of [ I I I I twins in gamma-Al2O3, and this model fit our experimental result well. In some nanorods, the ordering of nanotwins gave rise to a local hexagonal-like structure. The twinned nanorods were usually enclosed by {100} and I I I I I facets, and their growth direction was changed from (I 10) into I 11). The surface structures of the nanorods confirmed that the {111}-type surface should be more stable.
关键词:
gamma-alumina;deposited alumina;transformation;diffraction;polymorphs;particles;coatings;boehmite;growth;films
Philosophical Magazine B-Physics of Condensed Matter Statistical Mechanics Electronic Optical and Magnetic Properties
High-resolution electron microscopy (HREM) images along the main symmetry directions, such as the twofold, threefold and fivefold axes, in icosahedral Al6Li3Cu (T2) phase have been obtained in this work. It is suggested that Li atom columns parallel to the electron beam may form a channel for the electrons. We have proposed a new atomic decoration model for the T2 phase in order to explain the HREM photographs. It has been suggested that the basic structure unit is a double triacontahedron with an edge length of 0.505 nm and that the T2 phase should be composed of a three-dimensional Penrose tiling format using these units. The edge length of the rhombohedron in the tiling is 0.505-tau-3 (= 2.139) nm. Projections of the model have been compared with the HREM images and it is shown that the match between them is satisfactory.
关键词:
cu;quasicrystals;(al,zn)49mg32;diffraction;symmetry;system;alloy;li
Materials Science and Technology
The initiation and propagation of a crack has been investigated in a (110)[110] oriented Ni3Al alloy single crystal by in situ TEM and using tension deformation at room temperature. The result has shown that the macropropagating direction of the crack was parallel to the tensile axis and the crack followed a zigzag path. Trace analysis indicated that the slip on (111) and (111) were activated during the crack propagating process. Calculations show that for this orientation of Ni3Al crystal, the stress concentration arising from the dislocation pile-up decided the choice of secondary slip systems and the macrodirection of the crack.
关键词:
deformation
H.M.Li
,
Z.J.Ding
金属学报(英文版)
A new parallel Monte Carlo simulation method of secondary electron (SE) and backscattered electron images (BSE) of scanning electron microscopy (SEM) for a complex geometric structure has been developed. This paper describes briefly the simulation method and the modification to the conventional sampling method for the step length. Example simulation results have been obtained for several artificial structures.
关键词:
Monte Carlo
,
null
,
null
