Effect of grain boundary complexions on the deformation behavior of Ni bicrystal during bending creep

Abstract

The dependence of creep deformation behavior of nickel bicrystal specimens on grain boundary (GB) complexion was investigated by performing a simulated bending creep test using molecular dynamics methods. Strain burst phenomena were observed during the low temperature [500 K, i.e., <0.3 * melting point of nickel (T)] bending creep process. Atomic strain and dislocation analyses showed that the time of occurrence of strain burst depends on how easily GB migration happens in bicrystal specimens. Specimens with kite monolayer segregation GB complexion were found to be stable at low temperature (500 K), whereas specimens with split-kite GB complexion were stable at a comparatively higher temperature (900 K). In case of further elevated creep temperatures, e.g., 1100 K and 1300 K, split-kite GB complexion becomes unstable and leads to early failure of the specimen at those temperatures. Additionally, it was observed that split-kite bilayer segregation and normal kite GB complexions exhibit localized increases in elastic modulus during bending creep process, occurring at temperatures of 1100 K and 1300 K, respectively, due to the formation of interpenetrating icosahedral clusters. Graphical abstract Representative creep curves during bending creep deformation of various grain boundary complexions at 900 K.

Grain Boundary Complexion Transitions

“…Recent results also suggest that, under certain conditions, flash sintering may also be initiated by grain boundary complexion transitions (125). Complexions can also reduce grain boundary diffusivity to resist high-temperature oxidation (126,127) and creep (128,129). For example, adding CuO to TiO 2 stabilizes a nanolayer complexion that enables activated sintering of powders 300°C below the eutectic temperature via enhanced grain boundary diffusivity (64).…”

Unravelling the Size‐Dependent Mechanical Properties of Nanocrystalline Face‐Centered‐Cubic Metals: From the Dislocation Point of View

“…In fact, accumulated evidences have hinted that nucleation and motion of dislocations, the main carrier of plastic deformation in CG metals, also serve as the prevailing contributing deformation mechanism in their NC equivalents for grain sizes down to %10 nm. [28][29][30][31][32] Despite some unusual accommodation mechanisms, such as GB sliding, [8] grain rotation and coalescence, [33,34] GB migration, [35] diffusional creep, [36] have also been reported to make some contributions to accommodate the plastic flow at room temperature (RT) and conventional strain rates. Under some extreme conditions, dislocation activities can persist to be activated in minuscule nanocrystals that are only several nanometers in size.…”

Dynamic Probing of Structural Evolution of Single Crystal Fe during Rolling Process Using Atomistic Simulation

“…Presently in order to comprehend the mechanical behavior of the nano‐rolling process, molecular dynamics (MD) simulation is an effective and reliable method for analyzing the atomistic mechanism and underlying physics of the deformation process. Numerous nanoscale studies on the static and dynamic deformation behavior of nanomaterials, solidification and heat treatment processes, have been performed using MD simulations and reported in the literature. In addition, MD simulation studies are flexible enough for dynamic investigations at a nanoscale level which is very difficult in case of experimental studies.…”