Nanoscratching-induced deformation in monocrystaline silicon is found to depend on the loading conditions. Molecular dynamics simulations reveal that amorphous phase transformation and nanotwins are the two major mechanisms. At a relatively low scratching depth, amorphous transformation occurs on the surface; however, when the scratching depth is greater than 1 nm, nanotwinning also emerges in ...

High-pressure torsion (HPT) is applied to a face-centered cubic CoCrFeMnNi high-entropy alloy at 293 and 77 K. Processing by HPT at 293 K produced a nanostructure consisted of (sub)grains of ~50 nm after a rotation for 180◦. The microstructure evolution is associated with intensive deformation-induced twinning, and substructure development resulted in a gradual microstructure refinement. Deform...

An open question in the behavior of metals subjected to shock is the nature of the deformation that couples to the phase transformation process. Experiments to date cannot discriminate between the role of known deformation processes, such as twinning or dislocations accompanying a phase change, and modes that can become active only in extreme environments. We show that a deformation mode not pr...

Nanocrystalline nc materials are known to deform via mechanisms not accessible to their coarse-grained counterparts. For example, deformation twins and partial dislocations emitted from grain boundaries have been observed in nc Al and Cu synthesized by severe plastic deformation SPD . This paper further develops an earlier dislocation-based model on the nucleation of deformation twins in nc fac...

Constitutive laws and crystal plasticity in diamond deformation have been the subjects of substantial interest since synthetic diamond was made in 1950's. To date, however, little is known quantitatively regarding its brittle-ductile properties and yield strength at high temperatures. Here we report, for the first time, the strain-stress constitutive relations and experimental demonstration of ...

The mechanical behavior of a metastable high entropy alloy (HEA) with composition Fe39-Mn20-Co20-Cr15-Si5-1Al at% is investigated. deformation mechanisms contributing to its properties are unveiled, by performing uniaxial tensile tests in situ synchrotron X-ray diffraction. Three distinct regimes detected. initial elastic and early dislocation-based plasticity followed moderate work hardening r...

Many crystalline rocks of the continental crust contain coarse-grained quartz as a main mineral (e.g., granitoids). Incipient deformation coarse quartz, which likely controls accumulation bulk strain in heterogeneously deformed crustal rock volumes, commonly develops microshear zones (MSZs) localized recrystallization. At mid-crustal conditions, where is mostly accomplished by subgrain rotation...

Contrary to the dislocation-driven ‘smaller-is-stronger’ size-effect in nanocrystals, size-dependence of strength deformation twinning, another carrier plasticity, still lacks universal understanding. Deformation twinning enables pseudoplastic strain >5% a shape memory ceramic (ZrHfO4)x (YTaO4)1−x. We use diffraction methods, microstructure analysis, and in-situ nanomechanical experiments uncov...