Efects of pre-strain on the compressive stress-strain response of Mo-alloy single crystal micro-pillars
- ORNL
- University of Tennessee, Knoxville (UTK)
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 (360-1400 nm) 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.
- Research Organization:
- Oak Ridge National Laboratory (ORNL); High Temperature Materials Laboratory; Shared Research Equipment Collaborative Research Center
- Sponsoring Organization:
- SC USDOE - Office of Science (SC)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 937526
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 17 Vol. 56; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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