Quantum-Theoretical Methods and Studies Relating to Properties of Materials

1989 ◽  
Author(s):  
Cari S. Ewig
Keyword(s):  
Theoretical Methods ◽  
Properties Of Materials

Metallurgical Effects of Grain Boundary Ledges

1977 ◽  
Vol 35 ◽  
pp. 126-129
Author(s):  
L.E. Murr
Keyword(s):  
Grain Boundary ◽  
Quantitative Data ◽  
Mechanical Treatment ◽  
Unit Length ◽  
Physical And Mechanical Properties ◽  
Direct Observations ◽  
Transmission Electron ◽  
Properties Of Materials ◽  
Thermo Mechanical Treatment ◽  
Ledge Density

Ledges in grain boundaries can be identified by their characteristic contrast features (straight, black-white lines) distinct from those of lattice dislocations, for example1,2 [see Fig. 1(a) and (b)]. Simple contrast rules as pointed out by Murr and Venkatesh2, can be established so that ledges may be recognized with come confidence, and the number of ledges per unit length of grain boundary (referred to as the ledge density, m) measured by direct observations in the transmission electron microscope. Such measurements can then give rise to quantitative data which can be used to provide evidence for the influence of ledges on the physical and mechanical properties of materials.It has been shown that ledge density can be systematically altered in some metals by thermo-mechanical treatment3,4.

A Stable Field Emission Electron Source

1977 ◽  
Vol 35 ◽  
pp. 58-59
Author(s):  
W.R. Bottoms ◽  
G.B. Haydon
Keyword(s):  
Field Emission ◽  
Signal To Noise Ratio ◽  
High Brightness ◽  
Electron Sources ◽  
Brightness Field ◽  
Current Densities ◽  
Properties Of Materials ◽  
Stable Field ◽  
Stable Current ◽  
Careful Design

There is great interest in improving the brightness of electron sources and therefore the ability of electron optical instrumentation to probe the properties of materials. Extensive work by Dr. Crew and others has provided extremely high brightness sources for certain kinds of analytical problems but which pose serious difficulties in other problems. These sources cannot survive in conventional system vacuums. If one wishes to gather information from the other signal channels activated by electron beam bombardment it is necessary to provide sufficient current to allow an acceptable signal-to-noise ratio. It is possible through careful design to provide a high brightness field emission source which has the capability of providing high currents as well as high current densities to a specimen. In this paper we describe an electrode to provide long-lived stable current in field emission sources.The source geometry was based upon the results of extensive computer modeling. The design attempted to maximize the total current available at a specimen.

Ultrawide measurement bench for measuring electromagnetic properties of materials in free space in a microwave range

2019 ◽  
pp. 55-59 ◽  
Author(s):  
V. N. Semenenko ◽  
◽  
V. A. Chistyaev ◽  
A. A. Politiko ◽  
K. M. Baskov ◽  
...  
Keyword(s):  
Free Space ◽  
Electromagnetic Properties ◽  
Microwave Range ◽  
Properties Of Materials

Everything you've always wanted to know about what your students think they know but were afraid to ask.

2000 ◽  
Vol 632 ◽  
Author(s):  
Eric Werwa
Keyword(s):  
Materials Science ◽  
Science Museum ◽  
Science And Engineering ◽  
Museum Exhibit ◽  
Museum Visitors ◽  
The Public ◽  
Materials Science And Engineering ◽  
Properties Of Materials ◽  
Formal Science ◽  
Lay Public

ABSTRACTA review of the educational literature on naive concepts about principles of chemistry and physics and surveys of science museum visitors reveal that people of all ages have robust alternative notions about the nature of atoms, matter, and bonding that persist despite formal science education experiences. Some confusion arises from the profound differences in the way that scientists and the lay public use terms such as materials, metals, liquids, models, function, matter, and bonding. Many models that eloquently articulate arrangements of atoms and molecules to informed scientists are not widely understood by lay people and may promote naive notions among the public. Shifts from one type of atomic model to another and changes in size scales are particularly confusing to learners. People's abilities to describe and understand the properties of materials are largely based on tangible experiences, and much of what students learn in school does not help them interpret their encounters with materials and phenomena in everyday life. Identification of these challenges will help educators better convey the principles of materials science and engineering to students, and will be particularly beneficial in the design of the Materials MicroWorld traveling museum exhibit.

Heat Flux Transducers in Studies of Heat-resistant Properties of Materials: on the Correctness of Readings

1997 ◽  
Vol 28 (7-8) ◽  
pp. 494-498
Author(s):  
T. G. Grishchenko ◽  
L. V. Dekesha ◽  
T. V. Mendeleeva
Keyword(s):  
Heat Flux ◽  
Heat Resistant ◽  
Properties Of Materials

Dependence of Elastic Properties of Materials on Their Porosity: Review of Models

2006 ◽  
Vol 9 (4) ◽  
pp. 335-355 ◽  
Author(s):  
Mariusz Kaczmarek ◽  
Marc Goueygou
Keyword(s):  
Elastic Properties ◽  
Properties Of Materials
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