The (20-1) interfaces are often observed in B19‚Äò martensite in the Ni-Ti shape memory alloys deformed beyond the reversibility limit. The mechanism of formation of these twins is assumed to be a combination of twinning and shuffle, which was found to be significantly more energy demanding than all other (pseudo)plastic straining mechanisms in NiTi, in particular the transformation twinning and the [100](001) plastic slip. The (20-1) twins are typically found forming quasi-regular wedge-like patterns, clearly resembling kink patterns observed in systems with extremely anisotropic plastic behavior. In this contribution, we will show that the (20-1) twinning can be obtained by combining the plastic kinking and the classical martensitic twinning. This mechanism does not require additional shuffle and might be, thus, energetically favorable. We explore the theoretical framework for describing the coupled kink-twin structure (suggesting the name kwink for it) at the continuum mechanics level, and suggest possible approaches for mathematical modelling of kwinks.

Towards continuum modelling of (20-1) interfaces in Ni-Ti martensite

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