Strengthening of nial matrix composites. Final report, October 1990-September 1993

Technical Report · Fri Oct 01 04:00:00 EDT 1993

OSTI ID:5554587

Arsenault, R J

It has finally been concluded that none of the existing theories could account for the observed high temperature strengthening, nor could the models or theories that the authors considered. This led to the prediction that the strengthening at high temperatures was the result of an increase in strength in the intermediate temperature range where the yield stress is relatively independent of temperature. The authors believe that the increase in stress is due to an increase in the athermal component of the yield stress, a component of the yield stress which is not overcome by thermal fluctuations. A TEM investigation was undertaken of continuous filament Al2O3/NiAl composites to determine if dislocations were generated as a result of the relaxation of the thermal residual stress. The data indicates that dislocation generation did indeed occur and there is a possibility that dislocation generation also occurs in shot fiber Al2O3/NiAl composites. This data may produce an interesting paradox since in Al2O3/NiAl composites, as the size of the reinforcement gets larger the dislocation density increases, but in SiC/Al composites, as the size of the SiC increases the dislocation density decreases at a constant volume fraction.

• Research Organization: Maryland Univ., College Park, MD (United States). Metallurgical Materials Lab.
• OSTI ID: 5554587
• Report Number(s): AD-A-271491/3/XAB; MML--1993-1; CNN: N00014-91-J-1353
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
FIBERS
LINE DEFECTS
MATERIALS
MATRIX MATERIALS
MECHANICAL PROPERTIES
NICKEL COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TENSILE PROPERTIES
TRANSITION ELEMENT COMPOUNDS