Disordered ferromagnetic state in the Ce-Gd-Tb-Dy-Ho hexagonal high-entropy alloy

Published on Apr 25, 2018in Journal of Alloys and Compounds4.65
· DOI :10.1016/J.JALLCOM.2018.01.331
S. Vrtnik11
Estimated H-index: 11
(University of Ljubljana),
Janez Lužnik5
Estimated H-index: 5
(University of Ljubljana)
+ 6 AuthorsJ. Dolinšek19
Estimated H-index: 19
(University of Ljubljana)
Abstract Rare-earth (RE) based hexagonal high-entropy alloys (HEAs) containing elements from the heavy half of the RE series (from Gd to Lu) are considered as prototypes of an ideal HEA, stabilized by the entropy of mixing with completely random distribution of the elements on an almost undistorted hexagonal close-packed (hcp) lattice. Here we present a study of the Ce-Gd-Tb-Dy-Ho hexagonal HEA (abbreviated as HEA-Ce), where a light-RE element Ce is alloyed with four heavy-RE elements. Since the binary mixing enthalpies of Ce with these elements are all zero, random mixing of the elements and an ideal solid solution can also be expected. Contrary to the expectations, a two-phase structure forms in the HEA-Ce, consisting of the majority hcp matrix and the rhombohedral precipitates that occupy a significant fraction of the sample's volume, with both phases having very similar composition. The “ideality” of the HEA-Ce solid solution is very likely compromised by the fact that the crystal structure of Ce is different from the structures of other elements. By performing measurements of the magnetic properties, the specific heat and the electrical resistivity in a magnetic field, we have determined the magnetic state of the HEA-Ce. Long-range-ordered periodic magnetic structures do not form (like they do in the hexagonal HEAs containing heavy-RE elements only), but the magnetic structure breaks up into ferromagnetically (FM) polarized spin domains distributed in size that orient randomly in zero field. The magnetically ordered state of the HEA-Ce can be described as a disordered FM state with a 2nd-order thermodynamic FM phase transition at T C = 140 K. The introduction of Ce did not yield any of the phenomena that are exceptional for the Ce-containing alloys and compounds (mixed valence, heavy-fermion, unconventional superconductivity).
📖 Papers frequently viewed together
208 Citations
1,917 Citations
46 Citations
#1Ya Zhao (TUT: Taiyuan University of Technology)H-Index: 6
#1Y.J. Zhao (TUT: Taiyuan University of Technology)H-Index: 1
Last. Yang Zhang (USTB: University of Science and Technology Beijing)H-Index: 16
view all 7 authors...
Abstract The formation of disordered solid solution in the hexagonal close-packed (hcp) structure in the GdHoLaTbY alloy and its mechanical properties were investigated in this study. The single hcp phase of the alloy in the as-cast state was confirmed by X-ray diffraction and scanning electron microscopy analyses. The compressive yield strength, fracture strength, and plastic strain of the alloy are 108 MPa, 880 MPa, and 21.8%, respectively, and the Vickers hardness is 96 HV. The results show t...
180 CitationsSource
#1S. JazbecH-Index: 7
#2Shiro KashimotoH-Index: 11
Last. Janez DolinšekH-Index: 20
view all 7 authors...
The analysis of low-temperature specific heat of rare-earth (RE)-containing quasicrystals and periodic approximants and consequent interpretation of their electronic properties in the T\ensuremath{\rightarrow}0limit is frequently hampered by the Schottky effect, where crystalline electric fields lift the degeneracy of the RE-ion Hund's rule ground state and introduce additional contribution to the specific heat. In this paper we study the low-temperature specific heat of a thulium-containing ...
9 CitationsSource
#1Janez LužnikH-Index: 5
#2Primož KoželjH-Index: 3
Last. J. Dolinšek (University of Ljubljana)H-Index: 19
view all 8 authors...
Rare earth based equimolar Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy (HEA) is a prototype of an ideal HEA, stabilized by the entropy of mixing at any temperature with random mixing of elements on the hexagonal close-packed lattice. In order to determine intrinsic properties of an ideal HEA characterized by the enormous chemical (substitutional) disorder on a weakly distorted simple lattice, we have performed measurements of its magnetic and electrical response and the specific heat. The results...
46 CitationsSource
#1Akira Takeuchi (Tohoku University)H-Index: 36
#2Kenji Amiya (Tohoku University)H-Index: 16
Last. Wei Zhang (DUT: Dalian University of Technology)H-Index: 132
view all 5 authors...
High-entropy alloys (HEAs) with an atomic arrangement of a hexagonal close-packed (hcp) structure were found in YGdTbDyLu and GdTbDyTmLu alloys as a nearly single hcp phase. The equi-atomic alloy design for HEAs assisted by binary phase diagrams started with selecting constituent elements with the hcp structure at room temperature by permitting allotropic transformation at a high temperature. The binary phase diagrams comprising the elements thus selected were carefully examined for the characte...
188 CitationsSource
#1Daniel B. MiracleH-Index: 71
#2J. D. MillerH-Index: 14
Last. Jaimie TileyH-Index: 28
view all 6 authors...
We develop a strategy to design and evaluate high-entropy alloys (HEAs) for structural use in the transportation and energy industries. We give HEA goal properties for low (≤150 °C), medium (≤450 °C) and high (≥1,100 °C) use temperatures. A systematic design approach uses palettes of elements chosen to meet target properties of each HEA family and gives methods to build HEAs from these palettes. We show that intermetallic phases are consistent with HEA definitions, and the strategy developed her...
431 CitationsSource
#1Kurt Binder (University of Mainz)H-Index: 136
#2A. P. Young (UCSC: University of California, Santa Cruz)H-Index: 61
This review summarizes recent developments in the theory of spin glasses, as well as pertinent experimental data. The most characteristic properties of spin glass systems are described, and related phenomena in other glassy systems (dielectric and orientational glasses) are mentioned. The Edwards-Anderson model of spin glasses and its treatment within the replica method and mean-field theory are outlined, and concepts such as "frustration," "broken replica symmetry," "broken ergodicity," etc., a...
3,337 CitationsSource
#1E. Segal (University of Pittsburgh)H-Index: 1
#2W.E. Wallace (University of Pittsburgh)H-Index: 36
Energy levels, eigenfunctions and magnetic moments of rare earth ions in a crystal field of hexagonal symmetry have been obtained using a Hamiltonian of the form, H = μBgJ · H +B40O40 + B60(O60 + 778 O66). Results are presented for all J values appearing in the rare earth series and for values of the parameters covering the situations in which the crystal field interaction is dominant, in which the interaction with the magnetic field is dominant and in which the two interactions are comparable i...
17 CitationsSource
Abstract The α-γ transition in cerium is considered as a Mott transition. From spectroscopic data it is concluded that the intra-atomic interaction, U, is considerably smaller than seems to have been believed in the past. Here it is argued that in metallic cerium, U is only of the order of a few electron volts. Current band calculations of the width of a 4f band state are presumably very unreliable, and correlation effects on the ionic crystal potential are probably of considerable importance. S...
315 CitationsSource
Magnetic Properties of Rare Earth Metals Edited by R. J. Elliott. Pp. ix+425. (Plenum: New York and London, September 1972.) $28.
329 CitationsSource
#1J.D. Speight (California Institute of Technology)H-Index: 2
Abstract Lattice spacing and magnetic susceptibility measurements have been made for Sm-type alloys in the GdLa, GdCe, GdPr and GdNd systems, in both the equilibrium and liquid quenched states. In all cases the liquid quenched alloys adopt the the close-packed hexagonal structure. Magnetic ordering, with incomplete cancellation of the atomic moments, has been observed in all the alloys at low temperatures (7 K ). The magnetic ordering is discussed in terms of interactions between the constit...
15 CitationsSource
Cited By10
#1Lu Shifan (GUET: Guilin University of Electronic Technology)H-Index: 1
Last. Guang Hui RaoH-Index: 10
view all 7 authors...
Abstract In this work, the relationship between configuration entropy and isothermal magnetic entropy change (ΔSM) of rare earth high-entropy alloys (HEAs) was studied. The results show that the matrix of rare earth HEAs GdTbHoEr exhibits the largest refrigerant capacity up to now (about 924.48 J kg−1 at a 5 T magnetic field). With the addition of non-magnetic elements La and Y, the configuration entropy increases, but the values of ΔSM and the refrigerant capacity decrease from 8.64 to 5.85 J k...
#1Zhiming Wang (Lancaster University)H-Index: 66
#1Z. Wang (TUT: Taiyuan University of Technology)
Last. Junwei Qiao (TUT: Taiyuan University of Technology)H-Index: 29
view all 6 authors...
Single-phase hexagonal close-packed structure of the ScYLaGdTbDyHoErLu high-entropy alloy was studied in detail. The applicability of the rule of mixture was analyzed with respect to the lattice constant, mechanical parameters, elastic properties, melting point, and hardness of the alloy. Significant tension-compression asymmetry has been found and explained by the strength differential effect during the uniaxial tests. Numerous deformation twins and high densities of stacking faults can be obse...
#1Lu Shifan (GUET: Guilin University of Electronic Technology)H-Index: 1
#2L. Ma (GUET: Guilin University of Electronic Technology)H-Index: 5
Last. Zhongwu Liu (SCUT: South China University of Technology)H-Index: 26
view all 9 authors...
Magnetocaloric effect of a single-phase high-entropy rare-earth alloy GdTbHoErY with the hexagonal close-packed (HCP) structure was studied. As the external field increases, the peak isothermal magnetic entropy change (ΔSM) of the alloy is accompanied by a hump, which widens the ΔSM peak and thus increases the refrigerant capacity (RC) value. Under a magnetic field of 5 T, the RC and the ΔSM reach 453 J kg−1 and 5.4 J kg−1 K−1, respectively. The high RC for the high-entropy alloy is mainly attri...
#2Yanwen ZhouH-Index: 1
view all 9 authors...
#1Ruixuan LiH-Index: 5
#2Junwei QiaoH-Index: 29
Last. Yong ZhangH-Index: 112
view all 4 authors...
Recently, various topics on high-entropy alloys have been reported and great amounts of excellent properties have been investigated, including high strength, great corrosion resistance, great thermal stability, good fatigue and fracture properties, etc. Among all these research activities, high-entropy alloys tend to form face-centered-cubic (FCC) or body-centered-cubic (BCC) solid solutions due to their high-entropy stabilization effect, while the hexagonal structures are rarely reported. Up to...
6 CitationsSource
#1Mitja Krnel (Jožef Stefan Institute)H-Index: 2
#1M. KrnelH-Index: 2
Last. Janez Dolinšek (University of Ljubljana)H-Index: 20
view all 8 authors...
Abstract We address the nature of the collective magnetic state in an ideal high-entropy alloy (HEA), representing a magnetically concentrated system with all lattice sites occupied by localized magnetic moments and containing randomness and frustration due to chemical disorder. Being a “metallic glass on a topologically ordered lattice”, HEAs possess simultaneously the properties of an ordered crystal and an amorphous glass. The influence of this crystal-glass duality on the collective magnetic...
5 CitationsSource
#1Tiandang Huang (DUT: Dalian University of Technology)H-Index: 4
#2Hui Jiang (SDUST: Shandong University of Science and Technology)H-Index: 14
Last. Tingju Li (DUT: Dalian University of Technology)H-Index: 26
view all 5 authors...
This study aimed to design and prepare the following four kinds of refractory high-entropy alloys (RHEAs): TiZrHf, TiZrHfSc, TiZrHfY, and TiZrHfScY. All the four RHEAs showed a hexagonal close-packed (HCP)-based structure. Both the strength and ductility increased in the TiZrHfSc alloy compared with the TiZrHf alloy because of the addition of Sc element and the formation of a fine needle-like lamellar structure in the former. The mechanical properties of TiZrHfY and TiZrHfScY alloys decreased af...
4 CitationsSource
#1S. Vrtnik (University of Ljubljana)H-Index: 11
#2Janez Lužnik (University of Ljubljana)H-Index: 5
Last. Janez Dolinšek (University of Ljubljana)H-Index: 20
view all 10 authors...
Abstract We present a study of the magnetic phase diagram and the magnetoresistance of a Gd–Tb–Dy–Ho–Lu "ideal" hexagonal high-entropy alloy (HEA), composed of the elements from the heavy half of the rare earth series only. The phase diagram contains an antiferromagnetic (AFM) state, a field-induced ferromagnetic (FM) state above the AFM-to-FM spin-flop transition and a low-temperature spin-glass state. The complex ( H , T ) phase diagram is a result of competition between the periodic potential...
10 CitationsSource
#1Junwei Qiao (TUT: Taiyuan University of Technology)H-Index: 29
#1J. W. Qiao (TUT: Taiyuan University of Technology)H-Index: 1
Last. M. C. Gao (AECOM)H-Index: 1
view all 8 authors...
The formation of octonary DyErGdHoLuScTbY and senary DyGdHoLaTbY and ErGdHoLaTbY high-entropy alloys (HEAs) with the hexagonal close-packed (HCP) structure was reported in this study. Experiments using scanning electron microscopy and x-ray diffraction confirmed the single HCP solid solution in the as-cast state for these three HEAs if the presence of minor rare-earth oxides due to contamination from processing is ignored. The measured compressive yield stress values for these HEAs at room tempe...
28 CitationsSource
#1C. Chattopadhyay (Indian Institute of Technology Madras)H-Index: 6
#1C. Chattopadhyay (Indian Institute of Technology Madras)H-Index: 1
Last. B.S. Murty (Indian Institute of Technology Madras)H-Index: 61
view all 3 authors...
Abstract A simple and completely predictive model has been developed to predict whether a multicomponent equiatomic alloy will form a single phase BCC, FCC, HCP or a combination of two or more solid solution phases or intermetallic compounds (IM) or an amorphous phase. This approach is based on the viscosity of alloys as a function of temperature, utilising the viscosities of its constituting elements, and suitably incorporating the crystal structure information. Some other parameters affecting ...
22 CitationsSource