Date | Time
16/12/2015 | 11 h 00 min - 14 h 00 min
The controversial microplasticity of polycrystalline magnesium
It is well known that plasticity of metallic materials is governed by a competition between the available twinning and slip systems. In magnesium, as well as in other hcp metals, twinning tends to become the dominant deformation mechanism with increasing grain size, with increasing strain rate and with decreasing temperature. The twinning to slip transition is, however, a very controversial topic, and contradictory evidence regarding transition grain sizes, strain rates and temperatures has been reported in the literature.
This talk will focus on recent research which reveals that twinning´s main contender is basal slip and that the transition between both mechanisms is related to the connectivity of grains that are favorably oriented for the latter [1,2]. It will be shown how increasing grain size and strain rate, and decreasing temperature, all contribute to limit the connectivity between grains that are well oriented for basal slip, thus favoring the dominance of twinning. Taking connectivity into consideration allows rationalizing the reported dispersion in transition grain sizes, strain rates and temperatures.
1. C.M. Cepeda-Jiménez, J.M. Molina-Aldareguia, M.T. Pérez-Prado. Acta mater. 88 (2015) 232-244.
2. C.M. Cepeda-Jiménez, J.M. Molina-Aldareguia, M.T. Pérez-Prado. Acta mater. 84 (2015) 443-456.