期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 106, 期 13, 页码 4986-4991出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0900740106
关键词
composites; damage confinement; endurance limit; semisolid processing
资金
- U.S. Department of Energy [DE-AC02-05CH11231]
- Office of Science
- Office of Basic Energy Sciences
- Division of Materials Sciences and Engineering
- National Defense Science and Engineering Graduate Fellowship
- Office of Naval Research
The recent development of metallic glass-matrix composites represents a particular milestone in engineering materials for structural applications owing to their remarkable combination of strength and toughness. However, metallic glasses are highly susceptible to cyclic fatigue damage, and previous attempts to solve this problem have been largely disappointing. Here, we propose and demonstrate a microstructural design strategy to overcome this limitation by matching the microstructural length scales (of the second phase) to mechanical crack-length scales. Specifically, semisolid processing is used to optimize the volume fraction, morphology, and size of second-phase dendrites to confine any initial deformation (shear banding) to the glassy regions separating dendrite arms having length scales of approximate to 2 mu m, i.e., to less than the critical crack size for failure. Confinement of the damage to such interdendritic regions results in enhancement of fatigue lifetimes and increases the fatigue limit by an order of magnitude, making these designed composites as resistant to fatigue damage as high-strength steels and aluminum alloys. These design strategies can be universally applied to any other metallic glass systems.
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