Dislocation dissociations in C11(b) MoSi2 and their impact on its plastic deformation

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PAIDAR V. CAK M. ŠOB Mojmír VITEK V.

Druh Článek v odborném periodiku
Časopis / Zdroj Intermetallics
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
Doi http://dx.doi.org/10.1016/j.intermet.2018.03.003
Klíčová slova Hexagonal metals; Mechanical properties; Twinning
Popis Using the DFT calculated gamma-surfaces possible metastable stacking faults have been found for the most common slip planes {013) and {110) in MoSi2. These calculations reveal three distinct stacking faults on {013) planes and one stacking fault on {110) plane. Owing to such multiplicity of metastable stacking faults there is a large number of possible dislocation dissociations. These dislocation splittings are analysed using the anisotropic elasticity and relevant stacking faults. The results show that the only dissociations of the < 331] dislocations favoured over the complete undissociated dislocations are on {013) planes either in one or two planes of this type. Splitting into {110) planes are never favoured. For the screw dislocation the dissociations on {013) planes lead to configurations that are sessile and block the dislocations glide in the case of compression along the [001] axis. This explains why for this orientation of compressive axis the single crystals are brittle at ambient temperature but dislocation glide may occur for compressive loading along different, less symmetrical directions. For the loading along the [001] axis the dislocation glide may take place at high temperatures when the cross slip releases the sessile screw dislocations on two {013) planes.
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