ELFT HÍRADÓ

[Szeminárium koordinátor <sem-admin AT wigner.hun-ren.hu>]

SZFI SeminarIspánovity, Péter DusánDepartment of Materials Physics, ELTE - 
SZFI, Wigner RCPExperimental and Theoretical Investigation of Dislocation 
Avalanches During Plastic DeformationTuesday, 31 March 2026, 10:00, KFKI 
Campus, Bldg. 1, 2nd floor, Conference RoomThe plastic deformation of 
crystals generally consists of a series of dislocation avalanches, which are 
localised and rapid deformation events. During these events, numerous 
dislocations move quickly and collectively. In the first part of the talk, I 
present the micromechanical and acoustic emission techniques we use to study 
these events experimentally, along with the obtained results. I will pay 
particular attention to our experiments on Zn micro‑pillars, in which we were 
the first to combine these two experimental methodologies. This allowed us to 
highlight the universal nature of dislocation avalanches, which show a strong 
resemblance to earthquakes.In the second part of the talk, I analyse the 
spatial extent and distribution of dislocation avalanches using 2D and 3D 
discrete dislocation dynamics simulations, together with the concepts of 
local yield thresholds and a weakest-link approach. I conclude that 
short-range interactions arising from static point-like obstacles (solute 
atoms, precipitates, etc.) introduce a characteristic length scale that 
governs the spatial extent of avalanches. I provide the physical explanation 
of this length scale through linear stability analysis. I demonstrate how 
avalanches can be linked to the eigenmodes of the system’s dynamical matrix, 
and how localisation manifests itself in terms of these eigenmodes. Finally, 
I address the practically important question of how the physics of avalanche 
behaviour can be incorporated into a continuum theory of 
dislocations. Minden érdeklődőt szívesen látunk! - Everyone is welcome 
to attend.Tamás Pusztaisem-admin AT wigner.hun-ren.hu