Quasicrystal Alloy Research Articles

Topological photonic quasicrystal alloy

Recently, a concept of topological photonic alloy was proposed by mixing magnetized and non-magnetized gyromagnetic rods in a two-dimensional square photonic crystal that supports tunable Chern bandgaps and robust chiral edge states even at a low concentration of magnetized rods. However, whether such a notion can be extended to non-crystalline systems is still an open question. Here, we theoretically demonstrate that topological photonic quasicrystal alloys can also sustain nontrivial Chern bandgaps and nonreciprocal chiral edge states. More interestingly, compared with the conventional topological photonic alloy with a crystalline lattice, we find that the topological photonic quasicrystal alloy with a non-crystalline lattice needs a higher threshold concentration of magnetized rods to open the Chern bandgap. These results not only broaden our understanding of topological photonic alloy but also offer a platform for exploring the unique properties of topological photonic quasicrystals.

Synthesis and Hydrogenation of the Ti45−xVxZr38Ni17 (5 ≤ x ≤ 40) Mechanically Alloyed Materials

The mechanically alloyed amorphous alloys of the Ti45Zr38Ni17 composition are known for their ability to form a quasicrystalline state after thermal treatment. It is also known that the amorphous and quasicrystal alloys belonging to the Ti45Zr38Ni17 family are able to store hydrogen and yield gravimetric densities above 2 wt.%. In this contribution, we report the results of research on the Ti45Zr38Ni17 system with vanadium doped instead of titanium. We found that the amorphous samples with moderate doping (x < 20) show the ability to absorb hydrogen while maintaining the amorphous state and they transform into the novel glassy-quasicrystal phase during annealing. Those materials with higher vanadium concentrations do not form entirely amorphous structures. However, they still can absorb hydrogen easily. It was also confirmed that the in situ hydrogenation of the amorphous alloys is a straightforward process without decomposition of the alloy. In this process, hydrogen does not attach to any particular constituent of the alloy, which would lead to the formation of simple hydrides or nanoclusters. Therefore, we were able to confirm the fully amorphous nature of the deuterides/hydrides of the Ti45−xVxZr38Ni17 with moderate V doping.

Enhanced electrochemical hydrogen storage properties of Ti49Zr26Ni25 quasicrystal alloy by doping with CO2-activated porous graphene

Ti49Zr26Ni25 quasicrystal alloy was fabricated via mechanical alloying and subsequent annealing. In order to enhance the electrocatalytic activity and conductivity of Ti49Zr26Ni25, the porous graphene (PoRGO) material was synthesized by a facile CO2 activation treatment of reduced graphene oxide (RGO). The composites of Ti49Zr26Ni25 doping with different amount of PoRGO were manufactured through ball milling. During the electrochemical hydrogen storage test, the porous Ti49Zr26Ni25 + PoRGO exhibited higher discharge capacity than Ti49Zr26Ni25 + CRGO and conventional Ti49Zr26Ni25 alloy. Moreover, the additive amount of PoRGO had great influence on the electrochemical properties of Ti49Zr26Ni25. Eventually, 5 wt% PoRGO modified Ti49Zr26Ni25 alloy electrode achieved a highest discharge capacity of 270 mAh/g. The large specific surface area and distinctive porous structure of porous graphene could offer more electrochemical active sites and facilitate the hydrogen diffusion. In the meantime, the cycling stability, high-rate dischargeability (HRD) and kinetic properties of Ti49Zr26Ni25 were also improved after PoRGO loading. Consequently, porous graphene can be potential used as the dopant for the modification of hydrogen storage alloys.

Enhanced electrochemical hydrogen storage performance of Ti49Zr26Ni25 quasicrystal alloy by coating with ZIF-8 derived porous carbon/MoS2 composite

Ti 49 Zr 26 Ni 25 quasicrystal alloy is prepared via mechanical alloying and subsequent annealing. ZIF-8 derived porous carbon (ZIF-8-C) is obtained through thermal treatment of zinc-based MOF ZIF-8. The solvothermal method is used to fabricate the ZIF-8 derived carbon/MoS 2 (C/MoS 2 ) composite. Then, the C/MoS 2 hexahedral particles are coated on the Ti 49 Zr 26 Ni 25 surface by ball-milling. For comparison, the Ti 49 Zr 26 Ni 25 + ZIF-8-C and Ti 49 Zr 26 Ni 25 + MoS 2 composites are also prepared. The C/MoS 2 modified Ti 49 Zr 26 Ni 25 displays higher hydrogen storage capacity of 279.1 mAh/g than separate ZIF-8-C or MoS 2 coated alloy and original Ti 49 Zr 26 Ni 25 . The superior properties may be due to the synergistic effect between high conductive flexible ZIF-8-C porous carbon and active MoS 2 . The preferable oxidation/corrosion resistance and cyclic stability are also realized. Moreover, Ti 49 Zr 26 Ni 25 + C/MoS 2 electrode exhibits higher exchange current density I 0 , limiting current density I L , hydrogen diffusion coefficient D and lower charge-transfer resistance R ct . The distinctive structural feature of C/MoS 2 can serve a rapid passageway and accelerate the hydrogen diffusion, thus further improving the kinetic properties and electrochemical activity of Ti 49 Zr 26 Ni 25 alloy electrode. • A facile solvothermal method is used to prepare ZIF-8 derived carbon/MoS 2 composite. • Ti 49 Zr 26 Ni 25 quasicrystal alloy coated with C/MoS 2 is obtained via ball milling. • The hydrogen storage capacity, HRD and kinetics performance of electrodes are improved. • The synergistic effect of MoS 2 and ZIF-8-C is advantageous to the hydrogen diffusion.

Corrigendum to “Al-Cu-Fe quasicrystals as the anode for lithium ion batteries” [J. Alloy. Compd. 805 (2019) 942–946

• Al-Cu-Fe quasicrystal alloy has certain lithium storage capacity. • Capacity of AlCuFe quasicrystal comes from Al. • Li atoms enter into the quasicrystal structure and cannot fully leave the quasicrystal during the first charge-discharge cycle.

The phase transition between decagonal quasicrystal and (1/0, 2/1) approximant in Al20Si20Mn20Fe20Ga20 high entropy quasicrystal alloy

High-entropy quasicrystals contain both multiple principal alloying elements and complex crystal structures, in contrast to usual high-entropy alloys that have simple crystal structures; however, microstructures of high-entropy quasicrystal-related phases have seldom been revealed. In this paper, we report complex domains of approximants of high-entropy decagonal quasicrystal (HE-DQC) in Al20Si20Mn20Fe20Ga20 alloy, investigated by spherical aberration-corrected scanning transmission electron microscopy at atomic-level resolution. Importantly, a phase transition from HE-DQC to a (1/0, 2/1)–type orthorhombic approximant, with a = 0.73 nm, b = 1.23 nm, c = 2.24 nm, was revealed. We found that multi-point nucleations and growth of the oriented hexagonal structural blocks and phason flips of the basic structural blocks lead to this phase transition. This study benefits understanding of the formation of periodic structures in HE-DQC.

Influence of cerium content on the microstructure and thermal expansion properties of suction cast Al-Cu-Fe alloys.

Low-expansion alloys are of great importance and can be used for the development of new aerospace materials. Herein, we report diverse rare earth quasicrystal alloys fabricated by the vacuum suction casting process. The effects of the addition of cerium (Ce) on the microstructure, thermal expansion properties and microhardness of the Al-Cu-Fe alloy were systematically investigated. This study discovered the tiny Al-Cu-Fe-Ce microstructure. A uniform distribution could be achieved after Ce addition amount is elevated. At the Ce addition amount of 1 at%, the lowest alloy thermal expansion coefficient was obtained. The alloy exhibited the maximum microhardness under these conditions. The microhardness of alloys containing 1 at% of Ce was approximately 2.4 times higher than the microhardness exhibited by alloys devoid of Ce additives. The coefficient of thermal expansion decreases by approximately 20%. The use of the suction casting process and the addition of an appropriate amount of Ce can potentially help design and develop Al-Cu-Fe-Ce alloys.

Microstructure and Nanoindentation Behavior of Ti40Zr40Ni20 Quasicrystal Alloy by Casting and Rapid Solidification

A Ti40Zr40Ni20 quasicrystal (QCs) rod and ribbons were prepared by conventional casting and rapid solidification. The X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimeter (DSC) techniques were used to investigate the microtissue, phase composition, and solidification features of the samples; the nano-indentation test was carried out at room temperature. The results show that a mixture of the α-Ti(Zr) phase and the icosahedral quasicrystal (I-phase) was formed in the Ti40Zr40Ni20 rod; the microstructure of Ti40Zr40Ni20 ribbons mainly consisted of the I-phase. The solidification mechanism of the I-phase was different in the two alloys. The I-phase in the quasicrystalline rod was formed by packet reaction while in the ribbons it was generated directly from the liquid. At room temperature, both samples had relatively high hardness and elastic modulus; the elastic modulus of the ribbons is 76 GPa, higher than the 45 GPa of the rod. The hardness of the ribbons was more than twice that of the rod.

Effect of the addition of cerium on the microstructure evolution and thermal expansion properties of cast Al-Cu-Fe alloy

The evolution of the microstructure and the variation in the thermal expansion properties of the Al 63 Cu 25 Fe 12 alloy by the addition of different amounts of cerium (Ce) are investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). Herein, a new series of quasicrystal alloys containing Ce are prepared. Results revealed that the Al 63 Cu 25 Fe 12 alloy contains icosahedral quasicrystal phase (I-phase), λ − Al 13 Fe 4 phase, β − Al 0.5 Fe 0.5 phase and Al 2 Cu 3 phase. The addition of Ce is confirmed to lead to grain refinement, formation of the Al 13 Ce 2 Cu 13 phase, disappearance of the λ − Al 13 Fe 4 phase. Furthermore, the area fraction of the I-phase in the alloy is confirmed to reach the maximum value, and the linear expansion coefficient of the alloy is the lowest due to the addition of Ce of up to 1 at%. The addition of Ce can reduce the linear expansion coefficient of the Al 63 Cu 25 Fe 12 alloy by ∼20%. The contribution of Ce will render better prospects for the application of Al-Cu-Fe-Ce materials.

An enhanced quasicrystalline Ti1.4V0.6Ni alloy electrode modified by uniformly covered RGO for nickel metal hydride battery

Herein, we provided a facile route to coat a flat and uniformly covered reduced graphene oxide (RGO) film on Ti1.4V0.6Ni quasicrystal alloy electrode surface by electrodeposition of graphene oxide and subsequent reduction with HI vapor. Raman spectrum showed HI has a better reduced effect than electrochemical reduction. The RGO coated alloy electrode exhibited a higher discharge capacity of 290.3 mA h g−1 and 23.8% higher capacity retention than the bare one after 50 cycles for the RGO layer effectively forbidding the direct contact of electrode and electrolyte. Moreover, Ti1.4V0.6Ni quasicrystal alloy with RGO coating exhibited faster hydrogen uptake kinetics by initial activation curve of gaseous hydrogen storage measurement and higher maximum hydrogen storage performance of 1.66 wt% than the bare Ti1.4V0.6Ni alloy. Thus, the enhanced properties of RGO as a multifunctional layer for Ti1.4V0.6Ni quasicrystal alloy were proved which could be achieved by a facile route.

Corrosive behavior of multi-phased quasicrystal alloys

Six quasicrystal alloys were created by varying their composition and subsequent microstructure. The corrosion of those quasicrystal alloys was investigated in an artificial seawater (3.5% NaCl solution) environment. These samples were tested in electrochemical experiments to obtain a current density and a corrosion rate. The results revealed that chemical composition and microstructure determined the corrosive behaviors of quasicrystal alloys. Specifically, Fe-based λ-phase showed pitting corrosion; while Cu-based β-phase and icosahedral-phase exhibited corrosion resistance. In the case of multi-phased alloys consisting of quasicrystal, they showed various corrosive behaviors according to the combination of phases. The alloys with λ-phase led to the higher current density and corrosion rate displaying pitting, galvanic, intergranular, and crevice corrosion. Meanwhile, the alloys with i-phase produced the lower current density and corrosion rate, presenting only weak galvanic and crevice corrosion. Additionally, higher concentrations of i-phase improve the corrosion resistance of multi-phase quasicrystal alloys. The understanding of corrosion mechanisms in quasicrystal alloys will open the way for the development of metal alloys that can be used in marine conditions.

Positive temperature dependence of compressive properties in an AlNiCo poly-quasicrystal fabricated by mechanical alloying and spark plasma sintering

In this study, ultrafine-grained Al71Ni14.5Co14.5 quasicrystal alloy was prepared by short-term mechanical alloying and spark plasma sintering process. The properties of the material exhibited a positive temperature dependence during the compression test up to 600 °C, such that both strength and strain enhanced by 61.6 and 75.3%, respectively. In contrast to other quasicrystals, work-hardening was also observed during the test at intermediate temperatures. To move towards prospective materials applicable at elevated temperatures, this anomalous behavior was analyzed by an investigation on the microstructure and fracture surface of the samples using TEM and SEM.

Design of quasicrystal alloys with favorable tribological performance in view of microstructure and mechanical properties

Quasicrystals have been used in various applications to improve wear resistance as well as friction. It is known that quasicrystal (i-phase) content and microstructure in alloys have a decisive effect on the mechanical properties and tribological performance. In this research, four (β + i)-dual-phased quasicrystal alloys with different i-phase content and grain size were developed to alleviate the brittleness of the i-phase with the help of the soft β-phase. The influences of the i-phase content and grain size were investigated through impact test, wear test, and analysis. Through the annealing process, the amount of the i-phase was increased by about 38% (59.24% → 81.75%), and, besides, the grain size of the i-phase was simultaneously increased from 3.47 μm up to 9.98 μm. As the amount of i-phase increased, it was possible to increase the hardness from 712 HV to 763 HV. Meanwhile, the increased grain size (i-phase) reduced the contact stress of the grain during wear testing; thus, the specific wear rate could be decreased from 2.21 × 10−4 mm3/Nm to 0.5 × 10−4 mm3/Nm. Not only that, but an experimental wear equation was obtained using empirical data to predict the wear behavior of the dual-phased alloys.

Quaternary Quasicrystal Alloys for Hydrogen Storage Technology

ABSTRACTThe Ti-Zr-Ni quasicrystal alloys have prospected to be one of the promising materials for hydrogen storage. This is because this type of quasicrystal contains 140 interstitial sites (T-sites) constituted in the Bergman Cluster that could accommodate hydrogen. The number of available sites is far greater than the number found in regular crystals, therefore the improvement of hydrogen storage capacity could be expected. For this study, we focus on the effect of substitution of Cr, in place of Ni in Ti-Zr-Ni amorphous and quasicrystal alloys. The studied samples are synthesized by the combination of mechanical alloying and sintering process. The subsequent measurements of electrochemical hydrogenation and dehydrogenation are carried out by a three-electrode cell at room temperature. The studied samples are structurally characterized by X-ray diffraction and their morphology is analyzed by scanning electron microscope and transmission electron microscope. The influence of the 4th substituted element on the possibility of a new-formed Cr quasicrystalline phase and the potential improvement of hydrogenation and dehydrogenation kinetics for both amorphous and quasicrystalline phase is evaluated. Our measurements showed the maximum discharge capacity achieved by Ti45Zr38Ni7Cr10 amorphous and Ti45Zr38Ni12Cr5 i-phase electrodes at a current density of 15 mA·g-1 to be 9.8 mAh·g-1and 55.2 mAh·g-1 respectively. The maximum estimated H/M value for the Ti45Zr38Ni12Cr5 i-phase electrode reached 1.36. These results are encouraging and show the merit of the usage of quasicrystals as hydrogen storage materials.

The Study of A New Symmetrical Rod Phase in Mg-Zn-Gd Alloys

Quasicrystal alloys have a wide application prospect because of excellent performances and characteristics; meanwhile, magnesium alloys are known as green engineering materials because of their high specific strength and light weight. Therefore, the study of Mg-Zn-Gd quasicrystal alloys is of great significance for the development of new materials. In this paper, Mg(70-x)Zn30Gdx(x=3,4,5) alloys were prepared by a conventional casting method and the morphologies and properties of these alloys were studied. There was a new symmetrical rod phase found in the Mg66Zn30Gd4 alloy and the symmetrical rod phase was identified as a ternary phase by mapping scanning and energy dispersive spectroscopy (EDS) analysis. The Zn/Gd ratio of the symmetrical rod phase was found to be 4.8 and the TEM images obtained were different from the typical diffraction spots patterns of quasicrystalline, which means it is unlikely to be quasicrystalline. With different melt holding time, the symmetrical rod phase evolved gradually over time from a lamellar eutectic structure; differential scanning calorimetry (DSC), heat treatment, and microhardness tests showed that the melting temperature of the rod phase was 453 °C and that its thermal stability and microhardness are better than quasicrystalline. Hence, the symmetrical rod phase is a new kind of complex metallic alloy phase whose composition and properties are close to those of quasicrystals but is not quasicrystalline.

Al–Cu–Fe quasicrystals as the anode for lithium ion batteries

In this paper, Al–Cu–Fe quasicrystal alloy was used as the anode material for lithium-ion batteries. The first specific discharge capacity of quasicrystal was 204 mA h/g. Cyclic voltammetry showed that the oxidation peak of the Al–Cu–Fe quasicrystal was at about 1.4 V. The reduction peak was at 0.3 V. The Al–Cu–Fe quasicrystals had a higher Li-ion diffusion impedance and Warburg impedance in the first cycle. X-ray diffraction analysis demonstrated that Li atoms enter into the quasicrystal structure and can-not fully leave the quasicrystal during the first charge-discharge cycle, which induces an irreversible capacity.

Preparation and electro-catalytic activity of nanoporous palladium by dealloying rapidly-quenched Al70Pd17Fe13 quasicrystalline alloy

Abstract The formation of nanoporous Pd was studied by electro-chemical dealloying a rapidly-quenched Al70Pd17Fe13 quasicrystal alloy in dilute NaCl aqueous solution, and the electro-catalytic activity of the nanoporous Pd towards methanol electro-oxidation was evaluated by cyclic voltammetry in 1 mol/L KOH solution. XRD and TEM analyses revealed that nano-decomposition of quasicrystal grains occurred in the initial stage of dealloying, and the fully dealloyed sample was composed of FCC-Pd phase. Scanning electron microscopy observation indicated that a maze-like nanoporous pattern was formed in the dealloyed sample, consisting of percolated pores of 5−20 nm in diameter in a skeleton of randomly-orientated Pd nano-ligaments with a uniform thickness of ~5 nm. A retention of ~12 at.% Al in the Pd nano-ligments was determined by energy dispersive X-ray spectroscopy (EDS). The nanoporous Pd demonstrated obvious electro-catalytic activity towards methanol electro-oxidation in alkaline environment.

Improved electrochemical hydrogen storage properties of Ti49Zr26Ni25 quasicrystal alloy by doping with Pd and MWCNTs

Ti49Zr26Ni25 quasicrystal was fabricated via mechanical alloying and subsequent annealing. The mixtures containing different amounts of Pd and MWCNTs were doped into the Ti49Zr26Ni25 alloy by ball-milling method. The icosahedral quasicrystal and Ti2Ni-type phases were the main phase compositions for the composite alloys. The composite alloy combined the large specific surface area and high conductivity of MWCNTs in conjunction with the excellent electrocatalysis ability of Pd, thus improving the discharge capacity and cycle stability of the matrix alloy. The Ti49Zr26Ni25 + MWCNTs + Pd electrode possessed a maximum discharge capacity of 281.6 mAh/g, outstandingly higher than those for Ti49Zr26Ni25 (206.1 mAh/g), Ti49Zr26Ni25 + MWCNTs (248.4 mAh/g) and Ti49Zr26Ni25 + Pd (259.3 mAh/g). The cycle stability and high-rate dischargeability were also enhanced. Furthermore, the studies on electrochemical reaction kinetics demonstrated that doping of Pd and MWCNTs accelerated the charge-transfer process, the two active materials played synergistic effect in enhancing the electrochemical activity and reaction kinetics for the Ti49Zr26Ni25 electrode.

Porous Al63Cu25Fe12 quasicrystals covered with (Al11.5Fe13.9Cu19.7)O54.9 nanosheets

Porous Al63Cu25Fe12 quasicrystal alloys with the surfaces and the wall of pores covered with abundant (Al11.5Fe13.9Cu19.7)O54.9 nanosheets were successfully fabricated through the combination of powder metallurgy and dealloying in NaOH solutions. Their compositions, microscopic morphology, and crystal structures were investigated using energy-dispersive X-ray spectroscopy, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. We found that the composite of porous Al63Cu25Fe12 quasicrystal alloys and (Al11.5Fe13.9Cu19.7)O54.9 nanosheets shows high catalytic performances in hydrogen production by methanol steam reforming at relatively low temperatures. X-ray photoelectron spectroscopy was used to analyze the catalytic mechanisms, and Cu was found to be the key element in this catalytic reaction.

3D Observation of Quasicrystal Alloy Using X-ray Differential Phase-Contrast Microscope with a Zone Plate

3D Observation of Quasicrystal Alloy Using X-ray Differential Phase-Contrast Microscope with a Zone Plate