Hello Jun Jiang,

the dislocations will annihilate first if they are close enough and "see" each other in terms of their local stress field or, secondly, if an (external) driving force brings them closer to each other.

Thank experts very much for shedding more light on my question. Dierk's detailed simulation work on the interaction between dislocation and GNBs is very interesting. I suppose it might be the checkerboard (hexagonal) structure rather than wall structure which stabilize the overall dislocation network.

Just wondering, to date, have there been any compelling theoretical work conducted on meso scale in polycrystals. I am aware that the computer power and memory might be the main limitation to extend this work due to the number of possible variables present in polycrystals.

Jun

These paper showing very systematic work on dislocation and grain boundaries, I particularly like the bicrystal Al Acta paper which shows direct GND measurements and provides possible theoretical dislocation mechanics. Thank Dierk very much for pointing out and shearing these work.

Dear Dierk, the next step of your work seems to extend the successfully developed plasticity simulation to study the GND formed network in polycrystal by taking the obtained grain boundaries effects into account. As you are one of the top experts in this field, may I ask what is the current state of GND related plasticity theoretical work on the development of GND formed network in deformed polycrystals.

To the best of my knowledge, the grain-grain interaction based simulation work showed some promising results to some degree as it has only been partially validated by experimental results.

I appreciate the complexity involved in polycrystals as it is such a long standing mystery and puzzled people for almost a century.

I am very grateful for your insightful discussions and suggestions to this junior researcher.

Jun

Yes, from our experimental results, the development of GND networks as functions of grain crystal orientations and other microstructure characteristics e.g. grain boundaries, triple junctions show rather large scattering.

Thank you very much for these proposed GND network development mechanisms. I do benefit a lot from them. The shear bands work on low SFE fcc crystal may suit well with some of my experimental results collected from tensile deformed polycrystal copper sample in which GND was recovered by HR-EBSD. I will quantitatively exam them to see to what degree these mechanisms work. Will let you know how it goes.

Jun