Physical properties of tin-containing high-entropy alloysGačnik, Darja (Avtor) Dolinšek, Janez (Mentor) tinhigh-entropy alloysmulticomponent alloysdisordered systemssuperconductivityThe concept of introducing a maximum amount of disorder, i.e., entropy, is realized in high-entropy alloys. At first, first generation high-entropy alloys were generated as single-phase solid solutions, but nowadays, the research has shifted towards second generation high-entropy alloys, i.e., non-equimolar multiphase alloys. In this Doctoral Thesis, we investigated the physical properties of tin-containing alloys. Low melting point (505.06 K) and high boiling point (2876 K) make tin quite different from other elements, with the vast difference between the two temperatures. Generally, tin has low solubility with other elements, so it promotes phase segregation in the alloys, being a perfect candidate for multiphase alloy structure. We specifically investigated six alloys: a ternary HfTiZr, a quaternary HfTiZrSn, and four pentary HfTiZrSnM (M = Fe, Ni, Cu, Nb) alloys. Only a non-tin alloy solidified into a single-phase solid solution, while other tin-containing alloys formed two-phase (only HfTiZrSnNb) or four-phase structures. We explored how chemical and structural disorders affect physical properties like superconductivity. For superconducting samples, we measured a relatively broad temperature range of the heat capacity peaks and the decrease in the resistivity, indicating that Cooper pairs do not form instantly and that superconducting phases have nano-regions that vary in critical temperatures. The magnetic properties of all the samples were analyzed, but a superconducting state was examined only for the HfTiZrSnNb alloy. The critical current, estimated via the Bean model, surpassed the NbTi characteristic critical current values even to four orders of magnitude. Moreover, the effect of applied mechanical pressure was evaluated with magnetization measurements up to 1.4 GPa. We performed the first-ever reported STM spectroscopy of superconducting high-entropy alloy to investigate its atomic-size inhomogeneity. We mapped the surface of the two-phase HfTiZrSnNb sample and detected the superconducting gaps that varied significantly, implying that the sample is a typical BCS-type “dirty” superconductor.20232023-04-07 08:15:02Doktorsko delo/naloga145127sl