Twinning induced plasticity steels are austenitic alloys in which mechanical twinning is a prominent deformation mode, and which exhibit exceptional combinations of ductility, work hardening and ultimate strength. The authors develop in the present paper a crystallographic theory to enable the quantitative investigation of the role of mechanical twinning in enhancing the properties of these all...

Twinning in metals is normally a permanent plastic deformation mechanism. Here we report reversible twinning in high stacking fault energy (SFE) aluminum. Twinning and spontaneous detwinning at the crack tip have been captured in situ during tensile straining under a transmission electron microscope. Both the in situ observation and the molecular dynamics simulations reveal a two-stage detwinni...

D anny de Vito would be happy to hear that for twin formation the paradigm 'smaller is stronger' still prevails. Twinning is a deformation process in crystals defined as the collective shearing of one portion of the crystal with respect to the rest. However, compared with plasticity based on dislocation glide, twinning has been scarcely studied in the deformation of metals. This is because twin...

Molecular dynamics simulations are performed to study the atomistic mechanisms governing the pseudoelasticity and shape memory in nickel–titanium (NiTi) nanostructures. For a h110i – oriented nanopillar subjected to compressive loading–unloading, we observe either a pseudoelastic or shape memory response, depending on the applied strain and temperature that control the reversibility of phase tr...

Deformation twinning was thought as impossible in ionic compounds with rock-salt structure due to the charge effect on {111} planes. Here we report the presence and formation mechanism of deformation {111} twins in the rock-salt manganese sulphide (MnS) inclusions embedded in a hot-rolled stainless steel. Based on the atomic-scale mapping under aberration-corrected scanning transmission electro...

The anisotropic microstructure of bone tissue is crucial for appropriate mechanical and biological functions of bone. We recently revealed that the construction of oriented bone matrix is established by osteoblast alignment; there is a quite unique correlation between cell alignment and cell-produced bone matrix orientation governed by the molecular interactions between material surface and cel...

PST TiAl crystals oriented such that the deformation axis lies in the (111) interfacial planes have been deformed in compression. This deformation produces so-called "channeled flow" in which the strain perpendicular to the (111) interfaces is zero, while the other two strains are equal and opposite in sign. Thus the sample simply shortens axially and spreads laterally in the channels defined b...

The tensile deformation response and texture evolution of aluminum alloyed Hadfield steel single crystals oriented in the h169i direction is investigated. In this material, the strain hardening response is governed by the high-density dislocation walls (HDDWs) that interact with glide dislocations. A microstructure-based visco-plastic self-consistent model was modified to account for mechanical...

In this study, we report the size-dependent transition of deformation twinning studied using in situ SEM/TEM tensile testing of defect-free [110] Au nanowires/ribbons with controlled geometry. The critical dimension below which the ordinary plasticity transits to deformation twinning is experimentally determined to be ∼170 nm for Au nanowires with equilateral cross-sections. Nanoribbons with a ...

ZK60 (Mg-Zn-Zr) alloys exhibited a variation in precipitates with aging, and their mechanical properties also changed. Microindentation tests were carried out on two types of ZK60 alloys of solid solution (T4) and peak aging (T6). Microstructure and texture evolution during indentation was investigated using electron backscatter diffraction. Twinning occurred near the indentation marks in most ...