Dynamic mechanisms of strengthening and softening of coherent twin boundary via dislocation pile-up and cross-slip

Dislocation pileups in small grains

“…DPUs formed against precipitates in a Mg-RE alloy were found to be significantly more complex than predicted by basic theory, due to the tortuous path imposed by the restricting second phase particles (Huang et al, 2019). Non-standard behaviour was also found for the interaction between a pileup and twin boundary in nickel as analysed by Li et al (2022). In first instance, the DPU was reflected; limited transmission from multiple sources only occurred after the formation of dislocation entanglements.…”

“…Secondly, DPUs do exist and interact with GBs in many interesting ways (Shen et al, 1988;Clark et al, 1992;Zhang et al, 2021;Bamney et al, 2022;Zhou et al, 2019;Murr, 2016;Zhao et al, 2020;Li et al, 2021;Liu et al, 2022a;Liu et al, 2022b;Britton and Wilkinson, 2012;Guo et al, 2014;Soer et al, 2004;De Hosson et al, 2006;Kondo et al, 2016;Piao and Khanh, 2021;Ruggles et al, 2020;Huang et al, 2019;Li et al, 2022). TEM observations do not allow to determine the length of dislocation segments in a bulk grain, but as the dislocation forest can be expected to be the main contributor for dislocations piling up at the GB (Mecking and Kocks, 1981;Gil-Sevillano et al, 1991;Schouwenaars, 2012), relatively short segments can be expected.…”

Relationship between Σ3 Boundaries, Dislocation Slip, and Plasticity in Pure Nickel

“…The plasticity can also be improved because special boundaries can result in a more uniform strain distribution during plastic deformation. Studies on fcc metals indicate that cross-slip can reduce the tip stress and activate intergranular plasticity [ 6 ]. On this basis, researchers have improved the plasticity of metals by adjusting the proportion and distribution of special boundaries and random boundaries, and the failure behavior resulting from poor plasticity during the application process can be reduced.…”

“…Therefore, it has a good plastic deformation basis. However, plastic deformation cannot proceed indefinitely because the dislocation slip is hindered by the GBs or other phases, resulting in stress concentration and, ultimately, material failure [ 6 , 21 ]. The interaction mechanisms of dislocations with twin boundaries or random boundaries are very complex and have been explored by nanoscale experiments and molecular dynamics simulations.…”

Novel Method for Image-Based Quantified In Situ Transmission Electron Microscope Nanoindentation with High Spatial and Temporal Resolutions

“…In situ TEM mechanical stages based on micro-electromechanical systems (MEMS) [ 1 ] have drawn more and more attention due to their versatile loading modes [ 2 ], flexible sample preparation methods [ 3 , 4 ], and high compatibility with TEM functions (e.g., double-tilt) [ 5 , 6 , 7 ]. MEMS-based in situ TEM mechanical stages have yielded numerous excellent results in recent years [ 3 , 8 , 9 , 10 , 11 , 12 , 13 ].…”