Density-driven ionization potential depression and its effects on material properties

1967 ◽

Vol 25 ◽

pp. 368-368

Author(s):

J. J. Kelsch ◽

A. Holtz

Keyword(s):

Electron Microscope ◽

Pressure Gradient ◽

Ionization Potential ◽

Simple Solution ◽

Specimen Surface ◽

Contamination Rate ◽

Local Pressure ◽

High Ionization ◽

Hydrocarbon Molecules ◽

Contamination Problem

A simple solution to the serious problem of specimen contamination in the electron microscope is presented. This is accomplished by the introduction of clean helium into the vacuum exactly at the specimen position. The local pressure gradient thus established inhibits the migration of hydrocarbon molecules to the specimen surface. The high ionization potential of He permits the use of relatively large volumes of the gas, without interfering with gun stability. The contamination rate is reduced on metal samples by a factor of 10.

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Grain boundary segregation in metals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130651 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1204-1205

Author(s):

C.L. Briant

Keyword(s):

Fracture Surface ◽

Grain Boundary ◽

Grain Boundaries ◽

Material Properties ◽

Electron Spectroscopy ◽

High Vacuum ◽

Boundary Segregation ◽

Grain Boundary Segregation ◽

Local Concentration ◽

The One

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.

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Relationships Between Grain Boundary Structure and Material Properties

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600001550 ◽

1980 ◽

Vol 38 ◽

pp. 366-369

Author(s):

Brian Ralph ◽

Barlow Claire ◽

Nicola Ecob

Keyword(s):

Grain Boundary ◽

Material Properties ◽

Main Property ◽

Grain Structure ◽

Boundary Structure ◽

Grain Boundary Structure ◽

Property Changes

This brief review seeks to summarize some of the main property changes which may be induced by altering the grain structure of materials. Where appropriate an interpretation is given of these changes in terms of current theories of grain boundary structure, and some examples from current studies are presented at the end of this paper.

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