Visokoentropijske zlitine

Pugelj, Nina (author), Marinšek, Marjan (mentor)

Cilj tega diplomskega dela je narediti pregled področja visokoentropijskih zlitin. Začne se z razlago definicije visokoentropijskih zlitin in termodinamiko nastanka visokoentropijske zlitine. Kot že ime pove imajo HEAs visoko entropijo v primerjavi s konvencionalnimi zlitinami. Visoka entropija naj bi stabilizirala HEA pri visokih temperaturah in povzročila, da HEAs prednostno tvorijo enofazne in ne večfazne raztopine. Poleg učinka visoke entropije so predstavljeni še trije ključni mehanizmi, ki naj bi HEAs dajali posebne mehanske lastnosti. To so popačenost mreže, počasna difuzija in koktajl efekt. Popačenost mreže je posledica različnih radijev atomov, ki sestavljajo posamezno HEA. Počasna difuzija in koktajl efekt sta oba posledica interakcij med različnimi atomi. Koktajl efekt zavzema vse lastnosti HEA, ki so posledice posameznih elementov in njihovih medsebojnih interakcij. Vsi štirje mehanizmi ali še niso dokazani ali pa niso prisotni v večji meri kot pri konvencionalnih zlitinah. Raziskave kažejo, da lastnosti HEAs niso posledica njim unikatnih mehanizmov, temveč že obstoječih. Zato so v delu opisane tudi mikrostrukture in njihov vpliv na mehanske lastnosti. Nato so razdelani bolj natančno nekateri mehanizmi v primerih HEAs. Poleg mehanskih lastnostih so predstavljene tudi funkcionalne lastnosti in sicer: biokompatibilnost ter katalitska aktivnost. Opisanih je tudi nekaj najbolj pogostih in nekaj popolnoma novih postopkov sinteze HEAs ter njihove prednosti in slabosti. Za konec je predstavljena še možna uporaba HEAs glede na njihove lastnosti.

• Language: Slovenian
• Keywords: visokoentropijske zlitine, konfiguracijska entropija, trdne raztopine, mehanske lastnosti
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2023
• PID: 20.500.12556/RUL-149580
• COBISS.SI-ID: 169283587
• Publication date in RUL: 07.09.2023

PUGELJ, Nina, 2023, Visokoentropijske zlitine [online]. Bachelor’s thesis. [Accessed 18 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=149580

Secondary language

• Language: English
• Title: High entropy alloys

Abstract

The goal of this paper is to make an overview of high entropy alloys. First it explains definition of high entropy alloy and the thermodynamics of its creation. As it is evident from their name HEAs have high entropy compared to conventional alloys. High entropy is assumed to stabilize HEA at high temperatures and cause HEA to form one phase solid solution instead of multiple phases. In addition to high entropy effect the paper discusses three other key mechanisms which are thought to give HEAs exceptional mechanical properties. These are lattice distortion, slow diffusion, and cocktail effect. Lattice distortion is a consequence of different sizes of atoms which make up a certain HEA. Slow diffusion and cocktail effect are both caused by interactions between different atoms. Cocktail effect encompasses all properties of HEA which arise from individual elements and their mutual interactions. However, all four mechanisms are either not yet proven or not present to greater extent than in conventional alloys. Research suggests that properties of HEAs are not the result of their unique and new mechanisms but rather already existing ones. Therefore, microstructures of HEAs and their effect on mechanical properties are also described. Along with mechanical properties the paper explores functional properties, namely biocompatibility and catalytic activity. Some common methods of synthesis are also presented together with their advantages and disadvantages. Finally, the paper lists some possible applications of HEAs based on their mechanical and functional properties.

• Keywords: high entropy alloys, configuration entropy, solid solutions, mechanical properties