Projects / Programmes
| Code |
Science |
Field |
Subfield |
| 1.02.01 |
Natural sciences and mathematics |
Physics |
Physics of condesed matter |
| Code |
Science |
Field |
| P002 |
Natural sciences and mathematics |
Physics |
| Code |
Science |
Field |
| 1.03 |
Natural Sciences |
Physical sciences |
High-entropy alloys; electronic, magnetic and thermal properties
Researchers (14)
Organisations (3)
Abstract
Within the past several years, a new approach to metallic alloy design with multiple principal elements in equimolar or near-equimolar ratios, termed high-entropy alloys (HEAs), has been proposed. According to this concept, the high entropy of mixing can stabilize disordered solid solution phases with simple structures like a body-centered cubic (bcc) or a face-centered cubic (fcc) with small unit cells, in competition with ordered crystalline intermetallic phases that often contain structurally complex giant unit cells. The HEA structure is characterized by a topologically ordered lattice with an exceedingly high chemical (substitutional) disorder. In order to achieve high entropy of mixing, the alloys must be composed of five or more major elements in similar concentrations, ranging from 5 to 35 at. % for each element, but do not contain any element whose concentration exceeds 50 at. %. Examples of HEAs are alloys derived within the systems Al-Si-Co-Cr-Cu-Fe-Mn-Ni-Ti, W-Nb-Mo-Ta-V, and Ta-Nb-Hf-Zr-Ti. Since many different elements can be alloyed, and the concentration of each element can vary significantly, the number of possible HEAs is virtually unlimited. Astonishingly, only about ten different HEAs have been studied up to date, making the field practically empty. Most existing studies focus on the relationship between phase, microstructure and mechanical properties, where it was demonstrated that HEAs exhibit enhanced mechanical properties like high hardness and solid–solution strengthening. The physical properties of HEAs remain largely unexplored. In 2014, the group of prof. J. Dolinšek (the principal investigator of this project proposal) has made a breakthrough in the field of physical properties of HEAs, by discovering the first superconducting HEA within the Ta-Nb-Hf-Zr-Ti system (P. Koželj et al., Phys. Rev. Lett. 113, 107001 (2014)).
The aims of this project are: (1) to synthesize, characterize and determine electrical, magnetic and thermal physical properties of new HEA systems with bcc structure within the systems Ta-Nb-Hf-Zr-Ti, transition-metals based Zr-Ti-V-Cr-Fe-Ni and aluminum–containing Al-Co-Cr-Cu-Fe-Ni; (2) to develop and investigate HEAs with hexagonal structure in systems containing rare-earths series of elements Ce-Ho-Dy-Y-Lu-Gd-Tb, which are expected to exhibit unconventional magnetism, a heavy-fermion-type conductivity and spin-fluctuation phenomena; (3) we shall also model theoretically the physical properties of a solid material possessing topologically ordered lattice with an exceedingly high degree of chemical (substitutional) disorder.
Since the field of physical properties of HEAs is still almost empty, our proposed research announces opening of a new physical branch – the physics of solid state materials that possess an exceedingly high chemical disorder on an otherwise topologically well ordered lattice. We expect to develop new original theoretical concepts for the understanding of HEA-type solid state materials with regard to the phase stability and electronic, magnetic and thermal properties. A practical result of our research will be the development of new HEA materials with novel/enhanced physical properties for the application in electronic, magnetic and magnetocaloric applications. The execution of the project will be done by the research and technical staff of three renowned Slovenian research/education institutions: (1) the Physics department of the Faculty of Mathematics and Physics of the Ljubljana University, (2) the Jožef Stefan Institute and (3) the Institute of Mathematics, Physics and Mechanics, in cooperation with Juelich Research Center, Germany, ETH Zurich, Switzerland and Chalmers University, Sweden.
Significance for science
Since the field of physical properties of high-entropy alloys is still almost empty, our proposed research announces opening of a new physical branch – the physics of solid state materials that possess an exceedingly high chemical disorder on an otherwise topologically ordered lattice. HEAs are thus metallic systems intermediate between regular periodic crystals and amorphous metallic glasses, possessing the features of both. We expect to develop new original theoretical concepts for the understanding of HEA-type solid state materials with regard to the phase stability and electronic, magnetic and thermal properties. A practical result of our research will be the development of new HEA materials with novel/enhanced physical properties for the application in electronic, magnetic and magnetocaloric applications. The originality and high novelty of the proposed research is hence guaranteed. Our results are expected to have significant impact on the development of novel theoretical concepts for the understanding of topologically ordered but chemically disordered solid state materials and on the development of novel metals-based materials for the technological application in the electronic, thermoelectric, magnetic and magnetocaloric applications.
Significance for the country
The aims of synthesis and physical-properties investigations of high-entropy alloys, representing metallic materials of a new generation, are targeted towards particular physical-chemical-mechanical properties or combinations of these, which are not present in classical metallic materials. There exist realistic possibilities that novel high-entropy materials, which show coexistence of a topologically ordered crystal lattice and an immense chemical (substitutional) disorder, will create new knowledge in materials science and open new technologies and new high-tech products. High-entropy alloys, where the electrical and thermal conductivities can be tuned by composition, offer a possibility to develop a “smart” material with good electrical and low thermal conductivity, which will find its application in the electronic and thermal (and/or thermoelectric) technologies. Rare-earths-containing high-entropy alloys that possess high magnetization and small hysteresis prompt for the use in magnetocaloric applications for refrigerators of a new generation, which will not contain a gaseous cooling medium that represents hazard for the environment in an event of uncontrolled release. Another magnetic application are strong permanent magnets of a new generation. The newly discovered high-entropy metallic materials and related technologies offer high business opportunities based on new products for small and medium enterprises. The social infrastructure is expected to develop significantly by establishing new companies and enterprises, accompanied by opening of new job possibilities.
Most important scientific results
Interim report,
final report
Most important socioeconomically and culturally relevant results
Interim report,
final report
