The study of plastic deformation of crystalline solids has a long history in physics and materials science, yet there are still unanswered questions. With his doctoral research, Dipl.-Ing. David Kurunczi-Papp aims to describe the fundamental properties of these complex systems consisting of highly entangled dislocation networks.
In material science, dislocations are the line-like defects in the ideally regular crystal structure. The physics of individual dislocation lines is well-known, however understanding their collective behavior requires a less conventional approach.
“The computational resources provided by today’s supercomputers allow us to simulate systems containing millions of degrees of freedom with unprecedented accuracy,” Kurunczi-Papp says.
Avalanches are known as a rapid, sudden flow of snow triggered spontaneously or by an external force. Surprisingly, avalanches are also observed in micrometer-sized metallic samples. These occur when a force plastically deforms the sample and causes a sudden movement of dislocations.
“My thesis quantifies dislocation avalanches based on material properties and the external load. This will impact the materials used in various applications needing to withstand heavy loads,” he says.
The doctoral dissertation consists of four articles published in scientific journals. The first three papers study dislocation systems with increasing complexity. The 4th paper is an excursion of Kurunczi-Papp into the trending world of high-entropy alloys (HEAs).
HEAs are metallic compounds consisting of five or more metals from the periodic table, proven to possess superior mechanical properties compared to conventional alloys. Kurunczi-Papp maps the compositional space of the 7-component sample alloy AlVCrFeCoNiMo using Bayesian optimization. His findings reveal the role of each element in the alloy and show how the presence of dislocations influences the ideal composition.
David Kurunczi-Papp is originally from Romania. He moved to Finland to work as a doctoral researcher in the Complex Systems research group at Tampere University.
Public defence on Friday 14 February
The doctoral dissertation of Dipl.-Ing./ M.Sc. (Eng) David Kurunczi-Papp in the field of computational physics titled From Rate Effects and Avalanches in Dislocation-Mediated Plasticity to Computer-Assisted High-Entropy Alloy Design will be publicly examined at the Faculty of Engineering and Natural Sciences on Friday, 14 February 2025 at 12 noon at Hervanta campus, in Rakennustalo, auditorium RG202 (Korkeakoulunkatu 5, Tampere).
The Opponent will be Professor Robert Maaß from the Federal Institute of Materials Research and Testing (BAM), Germany. The Custos will be Professor Lasse Laurson from Tampere University, Finland.