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3D x-ray microprobe investigation of local dislocation densities and elastic strain gradients in a NiAl-Mo composite and exposed Mo micropillars as a function of prestrain
- Source :
- Journal of Materials Research. 25:199-206
- Publication Year :
- 2010
- Publisher :
- Springer Science and Business Media LLC, 2010.
-
Abstract
- 3D spatially-resolved polychromatic microdiffraction was used to nondestructively obtain depth-dependent elastic strain gradients and dislocation densities in the constituent phases of a directionally solidified NiAl–Mo eutectic composite consisting of ∼500–800 nm Mo fibers in a NiAl matrix. Measurements were made before and after the composite was compressed by 5% and 11%. The Mo fibers were analyzed both in their embedded state and after the matrix was etched to expose them as pillars. In the as-grown composite, due to differential thermal contraction during cooldown, the Mo phase is under compression and the NiAl phase is in tension. After the prestrains, the situation is reversed with the Mo phase in tension and NiAl matrix in compression. This result can be explained by taking into account the mismatch in yield strains of the constituent phases and the elastic constraints during unloading. The dislocation density in both the Mo and NiAl phases is found to increase after prestraining. Within experimental uncertainty there is little discernible difference in the total dislocation densities in the Mo phase of the 5% and 11% prestrained specimens. However, the density of the geometrically necessary dislocations and the deviatoric strain gradients increase with increasing prestrain in both the Mo and NiAl phases.
- Subjects :
- Nial
Materials science
Yield (engineering)
Tension (physics)
Mechanical Engineering
Composite number
Condensed Matter Physics
Compression (physics)
Mechanics of Materials
Phase (matter)
General Materials Science
Composite material
Dislocation
computer
computer.programming_language
Eutectic system
Subjects
Details
- ISSN :
- 20445326 and 08842914
- Volume :
- 25
- Database :
- OpenAIRE
- Journal :
- Journal of Materials Research
- Accession number :
- edsair.doi...........32bc9f1d6235d4eea560779c9d8ac14c