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Effects of pre-strain on the compressive stress–strain response of Mo-alloy single-crystal micropillars
- Source :
-
Acta Materialia . Oct2008, Vol. 56 Issue 17, p4762-4770. 9p. - Publication Year :
- 2008
-
Abstract
- Abstract: A NiAl–Mo eutectic was directionally solidified to produce composites with well-aligned single-crystal Mo-alloy fibers embedded in a NiAl matrix. They were pre-strained by compressing along the fiber axis and then the matrix was etched away to expose free-standing micropillars having different sizes (360–1400nm) and different amounts of pre-strain (0–11%). Compression testing of the pillars revealed a variety of behaviors. At one extreme were the as-grown pillars (0% pre-strain) which behaved like dislocation-free materials, with yield stresses approaching the theoretical strength, independent of pillar size. At the other extreme were pillars pre-strained 11% which behaved like the bulk, with reproducible stress–strain curves, relatively low yield strengths, stable work-hardening and no size dependence. At intermediate pre-strains (4–8%), the stress–strain curves were stochastic and exhibited considerable scatter in strength. This scatter decreased with increasing pre-strain and pillar size, suggesting a transition from discrete to collective dislocation behavior. [Copyright &y& Elsevier]
Details
- Language :
- English
- ISSN :
- 13596454
- Volume :
- 56
- Issue :
- 17
- Database :
- Academic Search Index
- Journal :
- Acta Materialia
- Publication Type :
- Academic Journal
- Accession number :
- 34460331
- Full Text :
- https://doi.org/10.1016/j.actamat.2008.05.030