c+a〉 Dislocations in deformed Ti–6Al–4V micro-cantilevers
Single α–β colony micro-cantilevers with an equilateral triangular cross-section and an apex at the bottom were machined from a polycrystalline commercial Ti–6Al–4V sample using a focused ion beam (FIB). Each cantilever contained several α lamellae separated by thin fillets of β. A nano-indenter was...
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Veröffentlicht in: | Acta materialia 2014-09, Vol.76, p.127-134 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Single α–β colony micro-cantilevers with an equilateral triangular cross-section and an apex at the bottom were machined from a polycrystalline commercial Ti–6Al–4V sample using a focused ion beam (FIB). Each cantilever contained several α lamellae separated by thin fillets of β. A nano-indenter was used to perform micro-bending tests (Ding et al., 2012) [1]. 〈c+a〉 Slip systems were selectively activated in the cantilevers by controlling the crystal direction along the micro-cantilever to be [0001]. Specimens for transmission electron microscopy were prepared from the deformed micro-cantilevers using a dual-beam FIB. Bright field scanning transmission electron microscopy was used to investigate the processes of slip nucleation, propagation and transmission through the α/β interface. Dislocations initiate first near the bottom of the cantilever and subsequently from the top. Both sets of dislocations move inward toward the neutral axis. Planar pyramidal {101¯1} slip was observed at the top (tension) but cross-slip was observed at the bottom (compression). All the 〈c+a〉 slip systems are equally stressed, but only a limited number is activated. This is tentatively interpreted in terms of dislocation transmission through the β fillets. |
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ISSN: | 1359-6454 1873-2453 |
DOI: | 10.1016/j.actamat.2014.05.010 |