Relaxation of thermal mismatch in discontinuously reinforced composites

Conference · Tue Aug 01 04:00:00 EDT 1995

OSTI ID:100321

Shi, N; Bourke, M A.M.; Goldstone, J A ^[1]; Arsenault, R J ^[2]

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1. Los Alamos National Lab., NM (United States)
2. Maryland Univ., College Park, MD (United States). Dept. of Materials and Nuclear Engineering

We have measured the dislocation density vol % and thermal residual elastic strain in NiAl matrices of 20 vol % Al{sub 2}O{sub 3} discontinuously-reinforced composites. As the size of the reinforcement increases the average dislocation density increases, and the corresponding thermal residual elastic strains decrease. The changes with respect to particle size in the dislocation density and residual strain can neither be explained by continuum theory nor by dislocation mechanics for homogeneous medium. A previously developed model (that satisfactorily describes the SiC/Al system) suggests that the misfit dislocation density decreases with increase in reinforcement size but this disagrees wit the current Al{sub 2}O{sub 3}/NiAl results. A new model is proposed to describe low-symmetry intermetallics, which are constrained in their ability to relax thermal mismatch because of a paucity of independent slip systems. The results are discussed in the context of continuum mechanics using finite element analyses and crystal plasticity.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 100321
• Report Number(s): LA-UR--95-2271; CONF-9511116--1; ON: DE95016802; CNN: Office of Naval Research Contract N00014-91-J-1353
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ALUMINIUM OXIDES
COMPOSITE MATERIALS
DISLOCATIONS
NICKEL ALLOYS
REINFORCED MATERIALS
RESIDUAL STRESSES
STRESS RELAXATION
THERMAL STRESSES