9457964 Hemker Dislocation motion in intermetallic alloys is known to be governed by the dislocation core geometry, but attempts to capitalize on this knowledge have been inhibited by the small number of experimental observations currently available. This study, which is unique in that it provides a very quantitative measure of dislocation core geometries by combining transmission electron microscopy with computer generated image simulations, provides a way of experimentally observing and characterizing dislocation core structures in intermetallic alloys. These quantitative observations are used to link the atomic structure of dislocation cores with the macroscopic mechanical properties in several different intermetallic alloys. It is known that the addition of iron to nickel-germanium reduces the anomalous flow strength behavior and eventually results in alloys in which the flow strength decreases "normally" with increasing temperature. Deforming a series of specimens that vary systematically in iron content and relating the measured fault energies with the yielding behavior of the individual alloys will provide valuable information about the sources of the flow strength anomaly in all L12 alloys. %%% A fundamental understanding of the processes that control dislocation motion in intermetallic alloys will allow alloy designers to modify alloy stoichiometry to maximize both ductility and high temperature strength. ***

Agency
National Science Foundation (NSF)
Institute
Division of Materials Research (DMR)
Application #
9457964
Program Officer
Bruce A. MacDonald
Project Start
Project End
Budget Start
1994-08-01
Budget End
2000-07-31
Support Year
Fiscal Year
1994
Total Cost
$308,900
Indirect Cost
Name
Johns Hopkins University
Department
Type
DUNS #
City
Baltimore
State
MD
Country
United States
Zip Code
21218