Abstract:
: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 approximately 2 mum, 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.
journal_name
Proc Natl Acad Sci U S Aauthors
Launey ME,Hofmann DC,Johnson WL,Ritchie ROdoi
10.1073/pnas.0900740106subject
Has Abstractpub_date
2009-03-31 00:00:00pages
4986-91issue
13eissn
0027-8424issn
1091-6490pii
0900740106journal_volume
106pub_type
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