Szkoła Doktorska AGH
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
Investigations of hyperfine parameters of iron in multi-component alloys, towards high entropy alloys
dr hab. inż. Jakub Cieslak
Supervisor’s email address:
Mossbauer studies of binary alloys made it possible to learn about the effect of various elements on the hyperfine parameters, e.g. Hf, IS or QS. This issue has been developed for binary alloys of small (<10%) dopant concentrations. A similar issue in the case of three or more component alloys has not been systematically investigated in detail. Mossbauer spectroscopy gives a unique possibility of detecting different configurations in the "iron-dopant" atom system, it also allows to determine the probability of their occurrence. It should be however checked to what extent the interaction of admixtures and their configuration in individual coordination zones have an impact on the hyperfine iron parameters. The number of possible "iron-dopant" atom configurations increases with dopant concentration. Consequently the model of the impact of foreign atoms for higher dopant concentrations in multi-component alloys should be developed. Introducing atoms of various sizes into the structure causes its local distortion. In such cases, an electric field gradient appears whose effect on the Mossbauer spectrum is important. It should be checked in what concentration range and for which systems one should consider the quadrupole splitting caused by the interaction of the quadrupole moment of the nucleus with the electric field gradient. The project includes systematic study of Fe- (Co, Cr, Ni, ...) systems in various configurations of dopant atom concentrations. Preparation of various series of samples is envisaged, starting from ternary systems and small total concentrations of admixtures in various proportions, through four- or more-component samples towards high entropy alloys. Parallel to the measurements, calculations of the electronic structure should be carried out, which will allow for proper interpretation of the measurement results and allow for the development of a model of the simultaneous impact of several admixtures on the hyperfine iron parameters.
The required apparatus for sample preparation (furnaces for arc melting, annealing), verification (XRD), Mossbauer measurements (in the temperature range 4 - 1000K) and electronic structure calculations is available at the Faculty of Physics and Applied Computer Science.