Formation of polytypes structures in Mg single crystals

Abstract

We report studies of polytypes structures (PSs) formed in the microstructure of deformed Mg single crystals. PSs emerge as co-products of lattice distortion developed in dislocations’ tangles due to reactions and rearrangements of dislocations to the lower energy configurations. TEM observations indicate that entanglements containing an excess content of 〈c〉-component dislocations that maintain dislocation interactions and the evolving pattern in a confined space nucleate PSs. The distortion and rotation of the hcp lattice induce the transition to the triclinic lattice originating PSs. The overlapping strain fields from mutually interlocked dislocations and stacking faults promote local shears and shuffles that develop polytypes domains within the PSs. Ab initio and molecular statics simulations permit understanding the processes governing triclinic and polytypic transformations in Mg and the role of dislocations in PSs’ self-assembly.