Accession Number : ADA302545

Title :   Strengthening of NiAl Matirix Composites.

Descriptive Note : Annual rept. 1 Oct 94-30 Nov 95,

Corporate Author : MARYLAND UNIV COLLEGE PARK

Personal Author(s) : Arsenault, R. J.

PDF Url : ADA302545

Report Date : 30 NOV 1995

Pagination or Media Count : 51

Abstract : A detailed mechanism has been developed which will predict the formation of vacancy-producing jogged-screw dislocations. The motion of these screw dislocations is the thermally-activated rate-controlling mechanism for both the matrix and the NiAl matrix composites. With the exception of very small subgrain or grain sizes and Al2O3 particle size (0.5 micrometer), the internal stress is independent of stress and temperature. The increase in the internal stress caused by the reinforcement is the strengthening mechanism. The apparent unusual result of an increase in dislocation density due to relaxation of the thermal residual stress as the particle size increases in Al2O3/NiAl composites has been explained by a new model. This model, which employs FEM and crystal plasticity, is based on the low symmetry of the NiAl B2 crystal structure which results in a paucity of independent slip systems. jg p.4

Descriptors :   *COMPOSITE MATERIALS, *MATRIX MATERIALS, *STRENGTH(MECHANICS), *DISLOCATIONS, *ALUMINUM, *NICKEL, *SCREWS, STRESSES, DENSITY, PARTICLE SIZE, MODELS, GRAIN SIZE, CRYSTALS, ALUMINUM OXIDES, INTERNAL, SYMMETRY, RESIDUAL STRESS, PLASTIC PROPERTIES, VACANCIES(CRYSTAL DEFECTS), THERMAL STRESSES, GRAIN BOUNDARIES.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Laminates and Composite Materials
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE