Abstract
An experimental study was conducted to examine the room-temperature fatigue crack-growth characteristics of shape-memory NiTi matrix composites reinforced with 10 and 20 vol.% of TiC particles. Microstructural characterization of these hot-isostatically-pressed materials shows that the TiC particles do not react with the NiTi matrix and that they lack any texture. Overall fatigue crack-growth characteristics were found to be similar for the unreinforced and reinforced materials. However, a slight increase in the threshold for fatigue crack initiation was noted for the composites. The fracture toughness, as indicated by the failure stress intensity factor range, was found to be similar for all materials. Neutron diffraction studies near the crack-tip of the loaded fracture NiTi specimen detected no significant development of texture at the crack-tip. These results are explained by recourse to fractographic observations. Finally, a comparison is made between the micromechanisms of fracture of metal matrix composites, which deform by dislocation plasticity, and those of the present NiTi-TiC composites, which deform additionally by twinning.
Original language | English (US) |
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Pages (from-to) | 208-216 |
Number of pages | 9 |
Journal | Materials Science and Engineering: A |
Volume | 289 |
Issue number | 1-2 |
DOIs | |
State | Published - 2000 |
Funding
The authors thank Professor S. Suresh (Massachusetts Institute of Technology) for the use of his mechanical testing facilities at the Laboratory for Experimental and Computational Micromechanics (LEXCOM) and for many helpful discussions. This work has also benefited from the use of the Los Alamos Neutron Science Center at the Los Alamos National Laboratory (LANL), funded by the US Department of Energy and operated by the University of California under Contract W-7405-ENG-36. RV and DCD acknowledge financial support from Daimler-Benz AG, Germany. Experimental help from Dr M.A.M. Bourke (LANL) and Mr G. LaBonte (LEXCOM) is also gratefully acknowledged.
Keywords
- Fatigue and fracture
- Metal matrix composites
- Micromechanisms
- Neutron diffraction
- Shape memory alloys
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- General Materials Science