Defect reconfiguration in a Ti–Al alloy via electroplasticity

Autor: J. W. Morris, Andrew M. Minor, Mark Asta, Yan Chong, Daryl C. Chrzan, Xiaoqing Li, Shiteng Zhao, Ruopeng Zhang, Anas Abu-Odeh, Eric Rothchild
Rok vydání: 2020
Předmět:
Zdroj: Nature Materials. 20:468-472
ISSN: 1476-4660
1476-1122
DOI: 10.1038/s41563-020-00817-z
Popis: It has been known for decades that the application of pulsed direct current can significantly enhance the formability of metals. However, the detailed mechanisms of this effect have been difficult to separate from simple Joule heating. Here, we study the electroplastic deformation of Ti–Al (7 at.% Al), an alloy that is uniquely suited for uncoupling this behaviour because, contrary to most metals, it has inherently lower ductility at higher temperature. We find that during mechanical deformation, electropulsing enhances cross-slip, producing a wavy dislocation morphology, and enhances twinning, which is similar to what occurs during cryogenic deformation. As a consequence, dislocations are prevented from localizing into planar slip bands that would lead to the early failure of the alloy under tension. Our results demonstrate that this macroscopic electroplastic behaviour originates from defect-level microstructural reconfiguration that cannot be rationalized by simple Joule heating. Transmission electron microscopy reveals the electroplastic effects in a Ti–Al alloy, which can be uncoupled from Joule heating effects. Electropulsing during deformation enhances wavy slip of dislocations, reconfiguring the dislocation pattern, and hence increases the ductility.
Databáze: OpenAIRE
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