Dy Addition Research Articles

Nickel catalyst supported on SiC incorporated SiO2 for CO2 methanation: Positive effects of dysprosium promoter and microwaves heating method

In this work, Dy-promoted Ni/SiC-SiO2 catalysts with varied Dy loadings (0–1 %) were developed using the wet impregnation method and evaluated for their effectiveness in CO2 methanation. The characterization results reveal that Dy addition can reduce the Ni crystallite size, enhance the dispersion of active phase and increase the catalyst’s reducibility. Among the prepared catalysts, the 0.5 %Dy-10 %Ni/SiC-SiO2 demonstrated the highest CH4 selectivity (100 %) and CO2 conversion (73.9 %) at 350 °C owing to its highest basic sites and H2 chemisorption capacity. The performance of this Dy-promoted catalyst diluted with different amounts of SiC, which was employed as a microwave susceptor and high thermal conductive dilution material, was also investigated in both microwave and electric reactor. Microwave heating leads to higher CO2 conversion compared to electric heating, regardless of reaction temperature and dilution factor due to selective heating and the random occurrence of hot spots, which are usually considered as micro-plasmas in the catalyst bed. However, further increase quantity of SiC decreased both CO2 conversion and CH4 selectivity regardless of heating method. This may be attributed to the appearance of extreme overheating and the absence of gentle overheating with increased amount of SiC in the microwave and electric reactors, respectively. The temperature-programmed oxidation results demonstrated that carbon deposition on the 0.5 %Dy-10 %Ni/SiC-SiO2 catalyst during 30 h of reaction can be significantly suppressed by microwave.

Effect of ultralow Dy and Gd contents on surface crystallization and domain wall motion of FeCuSiBNbMo alloys

Surface crystallization of Fe-based melt-spun ribbons with high saturation induction leads to the formation of coarse grains after nanocrystallization, which results in a deterioration of the soft magnetic properties. Herein, doping with an ultralow concentration (0.1 at.%) of RE (RE = Dy and Gd) inhibits the surface crystallization of melt-spun FeCuSiBNbMo samples using industrial-grade Nb–Fe raw materials. This inhibition of surface crystallization promotes the formation of uniform and ultrafine nanograins after optimal annealing. Furthermore, the movement of domain wall is significantly affected by the presence of large grains (∼600 nm) in the free surface, which exerts a strong pinning effect on the domain wall motion. This pinning effect can be attributed to the higher magnetic anisotropy energy of the free surface compared to that of the nanocrystal region. The low coercivity observed in the samples with 0.1 at.% Dy and Gd addition is ascribed to the presence of dense and ultrafine nanocrystals, low effective magnetic anisotropy, and a weak pinning effect. This work provides insights into the relationship between surface crystallization, coercivity, domain wall motion, and magnetic anisotropy energy in Fe-based nanocrystalline ribbons.

Dy6Fe13Cu grain boundary restructured Nd-Fe-B permanent magnets

Pursuing high coercivity has long been a focus of the whole Nd-Fe-B community to enable its widespread application in emerging sectors. In the present work, the controlling mechanism of high-coercivity Dy6Fe13Cu grain boundary restructured (GBR) magnets is investigated. Compared to the starting magnet with a coercivity value of 17.2 kOe, the coercivity of the restructured magnet with 3 wt% Dy6Fe13Cu (equals to 1.65 wt% Dy) increases to 22.8 kOe, with the coercivity increment level of 3.39 kOe per unit weight percentage of Dy addition. Results show that low-melting-point Dy6Fe13Cu additive contributes to the formation of continuous intergranular layer isolating ferromagnetic 2:14:1 grains and promotes the infiltration of Dy into the (Nd, Dy)2Fe14B magnetically hardening shell. Both effects enable the more efficient utilization of scarce Dy to enhance the coercivity of bulk Nd-Fe-B magnets. It delights future work for fabricating high-coercivity magnets via the GBR approach.

Microstructure and magnetic properties of Dy-added Alnico alloys

Alnico permanent alloys are still irreplaceable and show great potential in high temperature applications considering their excellent thermal stability, while the market for Alnico alloys is limited by their low coercivity. Rare-earth addition has been shown to increase the coercivity of Alnico alloys. In this work, the effects of Dy-addition on the crystal structure, microstructure, spinodal decomposition phases and magnetic characteristics of Alnico alloys were systematically investigated. The results indicate that the Dy element forms Dy-rich precipitates and influences the morphology and composition of spinodal decomposition structure. The 0.3 wt% Dy addition improves the coercivity from 132 kA·m−1 for the Dy-free alloys to 141 kA·m−1 for the Dy-added alloys and slightly optimizes the thermal stability. The enhancement of coercivity is attributed to the refined and uniform spinodal decomposition structure by reducing the mismatch degree and coherency strain. However, the magnetic properties of the 0.6 wt% Dy added alloy decrease due to the damaged structure with excessive Dy-rich phases and more connected α1 phases. A method for improving coercivity and thermal stability is suggested.

On dysprosium utilisation in multi-main-phase Nd–Dy–Fe–B magnets with core–shell microstructures

The development of high-performance Nd–Dy–Fe–B magnets that minimise the consumption of the scarce rare earth (RE) element Dy remains a major global scientific and technological quest. Here, we designed an alloy microstructure comprising of a uniform Dy-lean core–Dy-rich shell in a series of multi-main-phase (MMP) Nd–Dy–Fe–B magnets. The resulting MMP Dy1 and Dy3 magnets with an overall Dy level of 1 and 3 wt.% possessed values of 0.48 and 0.29 T/wt.% of coercivity increment per unit weight percentage of the Dy addition, respectively. Most importantly, the resulting MMP Dy3 magnet exhibited a high coercivity (2.38 T), an excellent thermal stability of the coercivity (|β| = 0.531%/°C), a high squareness factor (> 95%), all with little diminishment in the remanent magnetisation (1.35 T) and maximum energy product (43.6 MGOe). These properties are superior to the currently available sintered Nd–Dy–Fe–B magnets which utilise higher levels of Dy of 5 wt.%. Via magnetic and multi-scale microstructural characterisation experiments and micromagnetic simulations, the formation of the Dy-lean core–Dy-rich shell microstructure is rationalised via solid-state-diffusion and solution reprecipitation during liquid-phase sintering. The Dy-lean core–Dy-rich shell microstructure and the non-ferromagnetic low-Fe RE-rich grain boundary phase led to the synergistic magnetic performance. This is significant in the context of the MMP Nd–Dy–Fe–B magnets being applied to large-scale production. The present work establishes a pathway for the more sustainable utilisation of Dy in permanent magnets via formation of a uniform core–shell microstructure.

Magnetic properties of gadolinium and/or dysprosium substituted Sm–Co nanocomposite ribbons

The present study reported the influence of heavy rare-earth elements (Gd and/or Dy) on Sm-Co-based melt-spun ribbons. Microstructure and magnetic properties of Sm-Co-based (Sm1–xRExCo5) ternary and quaternary systems were investigated. The X-ray diffraction, Auger spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses reveal the presence of the 1:5H and 2:17R phases in the as-spun ribbons. A high-temperature magnetic measurement reports a Curie temperature (TC) at ∼825 and ∼869 K in Sm0.6Gd0.4Co5 (ribbon A) and Sm0.6Gd0.3Dy0.1Co5 (ribbon B), respectively. A low-temperature magnetic measurement on Sm0.6Gd0.3Dy0.1Co5 ribbons exhibits a type-2 SR (spin reorientation) behaviour at ∼72 K, which arises due to the presence of the DyCo5 phase. Room temperature magnetic measurements reveal that overall magnetic measurement (OMP) is about 24 and 29.9 for ribbons A and B, respectively. Consequently, the comparative investigations profess that ribbon B shows better magnetic performance due to Dy addition with reduced grain size. This observation indicates that the Gd and Dy substituted Sm–Co magnet can be a potential magnet for high-temperature applications.

Crystallization Kinetics on Melt Spun and HPT-Processed Zr62Cu22Al10Fe5Dy1 Metallic Glass

The influence of conventional and accumulative HPT (Acc. HPT) process on structural properties of Zr62Cu22Al10Fe5Dy1 metallic glass (MG) phase is examined by X-ray diffraction (XRD) technique. The XRD results showed that HPT process leads to free volume generation in MG. Free volume increases with the number of anvil turns in the conventional HPT process, while the highest free volume increment was observed in Acc. HPT process. To understand the role of latent crystalline phases on free volume, thermal stability and crystallization kinetics of Zr62Cu22Al10Fe5Dy1 MG are investigated by non-isothermal heating using differential scanning calorimetry (DSC). Thermal investigation indicates Dy addition results in increased activation energy along with lower nucleation rate during crystallization. As the initial amorphous phase significantly influences crystallization behavior, d-spacing analysis of amorphous hump is carried out to predict latent crystalline phases. Strong correlation was observed between latent crystalline phases and intermetallic compounds in devitrified Zr62Cu22Al10Fe5Dy1 alloy.

Effect of the Rare Earth Metals (Tb, Nd, Dy) addition for the modification of nickel catalysts supported on alumina in CO2 Methanation

In the current research, a group of rare-earth metals functionalized mesoporous Ni-M/Al2O3 (M = Tb, Dy, Nd) composite oxides were prepared by the one-pot sonochemical pathway and applied in the CO2 methanation procedure. Promoters can partially influence the textural and catalytic characteristics of Ni–Al2O3 catalysts. Physicochemical characteristics of the as-fabricated catalysts were identified utilizing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Energy-dispersive X-ray spectroscopy (EDS), Temperature Programmed Reduction (H2-TPR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) analyses. Among the specimens, the catalyst modified by Terbium (Tb) manifested better catalytic performance and CH4 selectivity, particularly at low temperatures (350–400 °C). The influence of reaction temperature (200–500 °C) was scrutinized below space velocity (GHSV) of 25,000 ml/gcath, atmospheric pressure, and stoichiometric ratio of CO2 to H2 (1: 4). The impact of the desired content of nickel and terbium was examined. The 25Ni–5Tb–Al2O3 operates the best function for CO2 methanation, which can attain the highest CO2 conversion of 66.93% at 400 °C at atmospheric pressure. The superior catalytic performance of 25Ni–5Tb–Al2O3 could be assigned to the appropriate fabrication method and the promotion effect of Terbium. The synthesis effect could be assigned to its large surface area, obtaining by the hot spot mechanism. The addition of Terbium promotes the Ni distribution on the supports as well as accelerates the positive reaction due to the oxygen vacancies of Terbium. Besides, these outcomes could be defined with the maximum distribution of active nickel sites on the catalyst and improvement in the catalyst reduction ability at low temperatures.

Biodegradable Zn–Dy binary alloys with high strength, ductility, cytocompatibility, and antibacterial ability for bone-implant applications

The unique combination of biodegradability, biocompatibility, and functionality of zinc (Zn)-based alloys makes them highly desirable for a wide range of medical applications. However, a long-standing problem associated with this family of biodegradable alloys in the as-cast state is their limited mechanical strength and slow degradation rate. Here we report the development of Zn-xDy (x = 1, 3, and 5 wt.%) alloys with high strength, ductility, cytocompatibility, antibacterial ability, and appropriate degradation rate for biodegradable bone-implant applications. Our results indicate that the mechanical properties of Zn–xDy alloys were effectively improved with increasing Dy addition and hot-rolling due to the second-phase strengthening. The hot-rolled (HR) Zn–3Dy alloy showed the best combined mechanical performance with an ultimate tensile strength of 270.5 MPa, a yield strength of 214.8 MPa, an elongation of 55.1%, and Brinell hardness of 75.9 HB. The corrosion and degradation rates of HR Zn–xDy alloys in Hanks’ solution gradually increased with increasing Dy addition due to the intensification of galvanic corrosion. The HR Zn–3Dy alloy showed high antibacterial ability against S. aureus and cytocompatibility toward MC3T3-E1 cells among all the HR alloys. Overall, the HR Zn–3Dy alloy can be considered a promising biodegradable material for bone implants. Statement of significanceThis work reports on Zn–xDy (x = 1, 3, and 5%) alloys fabricated by Dy alloying followed by hot-rolling for biodegradable bone-implant applications. Our findings demonstrate that the hot-rolled (HR) Zn–3Dy alloy showed the best combined mechanical performance with an ultimate tensile strength of 270.5 MPa, a yield strength of 214.8 MPa, an elongation of 55.1%, and Brinell hardness of 75.9 HB. The corrosion and degradation rates of HR Zn–xDy alloys in Hanks’ solution gradually increased with increasing Dy addition due to the intensification of galvanic corrosion. Furthermore, the HR Zn–3Dy alloy showed greater antibacterial ability against S. aureus and the best cytocompatibility toward MC3T3-E1 cells among all the HR alloys.

Removal of elemental mercury from coal combustion flue gas using recyclable Dy modified Mn-Fe mixed oxide nanoparticles

To enhance its SO2 tolerance and further improve the Hg0 removal performance, Dy was applied to modify the Mn-Fe mixed oxide sorbent. Results showed that appropriate Dy addition promoted the Mn3O4 formation, decreased the grain size, enlarged the surface area, increased the chemisorbed oxygen concentration and weak acid sites of sorbent, thus promoting its Hg0 removal performance. The calcination at excessive high temperature would result in the grain growth and decrease the sorbent activity. MnFeDy0.4-400 (with Dy/Fe molar ratio of 0.4 and calcined at 400 °C) exhibited the best Hg0 removal performance. Around 86% Hg0 removal could be achieved over MnFeDy0.4-400 under 5% O2, 300 ppm NO, 1000 ppm SO2 and 3% H2O. O2 could replenish the active oxygen species and maintain the surface metal ions at high-valent state, which was essential to Hg0 removal. With presence of NO, abundant active nitrogenous species could form over MnFeDy0.4-400 surface, contributing to the Hg0 removal. Due to strong basicity, Dy species functioned as a SO2 trap agent to preserve the predominant active species Mn3O4, thereby improving the capacity of sorbent to resist SO2. The formation of active nitrogenous species over MnFeDy0.4-400 would not be significantly affected by SO2. Moreover, MnFeDy0.4-400 had superparamagnetic property. This enabled spent MnFeDy0.4-400 to be separated from fly ash by magnetic separation. Regeneration and stability evaluation tests manifested that MnFeDy0.4-400 might be a promising material that could be utilized for Hg0 removal from flue gas.

A high-strength Mg-8Zn-1Mn-3Sn-1.2Gd alloy with fine MgSnGd particles by Dy modification

In the current work, we successfully prepared Mg-8Zn-1Mn-3Sn-1.2Gd-0.2Dy alloy with an excellent combination of ultimate tensile strength and ductility. The mechanism of the Dy-modified MgSnGd phase and its effect on the microstructure and mechanical properties of as-cast and as-extruded alloy were systematically investigated. Experimental results reveal that a new phase MgSn (Gd, Dy) is formed with Dy addition to Mg-8Zn-1Mn-3Sn-1.2Gd alloy, MgSn (Gd, Dy) phase can act as an effective heterogeneous nucleation site of MgSnGd phase. Meanwhile, the addition of Dy consumes Sn and Gd atoms, reducing the enrichment of solute atoms and inhibiting the MgSnGd phase's growth. The Dy addition can effectively promote the dynamic recrystallization process due to the combined effects of the refined grain structure of as-cast alloy and the particle-stimulated nucleation effect caused by dispersed MgSnGd phase. The alloy exhibits an excellent combination of high strength and ductility with the ultimate tensile strength of 384 MPa and an elongation of 14.5%. The fine-grained structure, the uniformly distributed MgSnGd particle, and MgSn (Gd, Dy) nanoparticles are mainly responsible for the ultra-high ultimate tensile strength. The high ductility is due to the fine-grained structure, appropriate decrease of dislocation density, and dynamic recrystallization.

Improvement of mechanical properties of hot extruded and aged Mg-Zn-Mn-Sn alloy through Dy addition

The effects of various Dy addition on the microstructure and mechanical properties of Mg-6Zn-1Mn-3Sn (wt%, ZMT613) alloys were investigated. The results showed significant grain refinement and new MgSnDy phases were detected with Dy addition of the as-cast ZMT613 alloy. A small amount of Dy (≤0.8 wt%) can hinder the proportion of dynamic recrystallized (DRXed) grains during hot-extrusion process and enhance the basal texture of the alloy. The MgSnDy high-temperature phase (HTP) particles inhibited the recovery process and retained substructures during solution treatment, which promoted the precipitation of the second phase. The as-aged ZMT613–0.2Dy alloy showed optimum mechanical properties, where yield strength, ultimate tensile strength, and elongation were 336 MPa, 399 MPa, and 4.4%, respectively.

Improvement of Mechanical Properties of Hot Extruded and Age Treated Mg-Zn-Mn-Sn Alloy Through Dy Addition

Improvement of Mechanical Properties of Hot Extruded and Age Treated Mg-Zn-Mn-Sn Alloy Through Dy Addition

Novel\ufeff eco-friendly low cost and energy efficient synthesis of (Nd\u2013Pr\u2013Dy)2Fe14B magnetic powder from monazite concentrate

Syntheses of Nd2Fe14B magnetic powder by conventional method is a complicated multi-step process, which produces harmful pollutants and consumes a huge amount of energy and resources. Herein we report a simple chemical route for the preparation of (Nd–Pr)2Fe14B magnetic powder using monazite concentrate as a precursor. Th, U, Sm, and La impurities were removed from monazite leachate by roasting, solvent extraction and leaching the concentrate. Purified leachate consisting of Nd and Pr Chlorides was added to the FeCl3 solution, and the solution produced was co-precipitated with NaOH. RE and Fe hydroxide precipitates were converted to the oxides by annealing at 700 °C. Boric acid and CaH2 were added in the RE and Fe oxides produced, and this mixture was reduced and diffused to (Nd–Pr)2Fe14B. Magnetic properties of the (Nd–Pr)2Fe14B produced were enhanced by introducing antiferromagnetic coupling, induced by Dy addition and efficient removal of CaO byproduct through ball milling in ethanol which increased the BHmax from 3.9 to 11.45 MGOe. Process reported is energy efficient, environment-friendly, time saving and low-cost.

Long afterglow from multi dopant transparent and opaque glass ceramic phosphor for white, red, yellow, and blue emissions: Zn2SiO4:Eu3+, Dy3+, Mn2+

In this paper, preparation of long afterglow phosphor with different emission colors in the system Zn2SiO4:Eu3+, Dy3+, Mn2+ was done via melt-quenching technique. The effect of adding mono-di- and tri-dopant on the phosphorescence properties was studied. Also, the effect of applying different heat treatment programs on the appearance of glass-ceramic (GC) to get transparent or opaque materials were optimized. DTA, XRD, SEM, UV–visible - NIR, and fluorescence spectrophotometer were used to characterize the obtained materials. The results revealed crystallization of willemite and zinc borate; both Mn and Dy addition enhanced the degree of crystallization while Eu depressed it. Heat treatment at 650 °C/5 h revealed transparent glass-ceramic (TGC), above this temperature opaque glass-ceramic was appeared. Calculation of optical band gap (Eopt), Urbagh energy (∆E) and refractive index were located in the range: 2.1–2.8 eV, 0.53–0.79 eV and 2.45–2.64 respectively. Lifetime decay was increased by increasing heat treatment temperature; it reaches ~2 h after irradiation at 260 nm for 30 min giving green emission at 558 nm. Visual appearance for the emitting light varies from white, red, yellow to blue color.

Thermodynamic model to predict bulk metallic glass forming composition in Zr-Cu-Fe-Al system and understanding the role of Dy addition

In the present investigation, we propose a theoretical approach to design the Zr-rich glass forming composition in Ni-free Zr-Cu-Al-Fe quaternary system under the thermodynamic framework. In this work, quaternary composition is designed by optimising chemical interaction and topological features among the constituent elements to determine enthalpy of chemical mixing (ΔHchem) and atomic size mismatch entropy (ΔSσ/kB) in a statistical framework of configurational entropy (ΔSconfig/R). Further, the effect of elemental Al and Fe addition in the Zr-Cu system on the glass forming ability (GFA) is analysed from thermodynamic viewpoint. Also, an attempt is made to understand the effect of Dy addition on thermodynamics and GFA of Zr-Cu-Al-Fe system. Subsequently, Zr62Cu22Al10Fe5Dy1 bulk metallic glass was synthesized for further investigation.

Effect of Dy doping on magnetostrictive and mechanical properties of Fe83Ga17 alloy

Fe83Ga17 alloy is a kind of promising magnetostrictive alloys with high magnetostrictive properties and a low saturation magnetic field. As-cast Fe83Ga17Dyx (x=0, 0.05, 0.1, 0.2, 0.4) polycrystalline alloys were prepared by arc melting. Effect of Dy doping on the microstructure, magnetostrictive and mechanical properties of as-cast Fe83Ga17 alloy was investigated. Results show that Dy-doped alloys exhibit a dual-phase structure containing the A2 matrix and Dy-rich precipitates (Fe56Ga34Dy10). Both magnetostriction and mechanical properties of Fe83Ga17 alloys are improved by Dy doping. A small amount of Dy addition (x=0.2) significantly causes Fe83Ga17 alloy to transform from typical brittle material (fracture strain ε<1%) to plastic material (ε≈11%). Correspondingly, the fracture mode transforms from intergranular fracture to dimple fracture. At the same time, the ultimate tensile strength and the magnetostriction rise up to 209 MPa and 64 ppm, respectively. Dy-rich precipitates disperse along the grain boundries and inside the grains, which plays an important role in the grain refinement and solution strengthening, and therefore, contribute to the enhancement of mechanical properties of the alloy. The improvement of magnetostriction could be attributed to the large lattice distortion induced by Dy atoms entering into the A2 matrix. Doping Dy into Fe-Ga alloys provides an effective solution to the brittleness in their applications.

Effects of Dy Addition on the Mechanical and Degradation Properties of Mg–2Zn–0.5Zr Alloy

As candidates for biomaterials, magnesium and its alloys have promising properties such as biodegradability and biocompatibility. However, their poor mechanical properties and rapid degradation rate limit clinical application; therefore, solving these issues is essential for practical application. Herein, different contents of dysprosium (Dy) (0, 0.5, 1, 1.5, 2, 3 mass%) are added to the Mg–2Zn–0.5Zr biomagnesium alloy to explore its effect on the mechanical and degradation properties. Assessments are conducted using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), immersion, and electrode chemical experiments. The results indicate that the addition of Dy significantly decreases the grain size, and the second phase is (Mg, Dy)7Zn3 with a body‐centered cubic structure. At a Dy content of 1.5 mass%, grain refinement and second‐phase strengthening result in the alloy having relatively good properties, with an ultimate tensile strength (UTS) = 150 ± 14 MPa, yield strength (YS) = 89 ± 3 MPa, and elongation (EL) = 9.2 ± 0.6%. The addition of Dy promotes the formation of a stable protective film and increases the electrode potential of the Mg matrix, resulting in a degradation rate of 0.89 ± 0.12 mm year−1. The results indicate that the alloy with 1.5 mass% Dy content is a promising candidate for using as a biodegradable material.

Microstructural Characterization, Functional Behavior and Deformation Mechanism of Ni&amp;gt;sub&amp;gt;54Mn &lt;sub&gt;25&lt;/sub&gt;Ga &lt;sub&gt;21-x&lt;/sub&gt;Dy &lt;sub&gt;x&lt;/sub&gt; High Temperature Shape Memory Alloys with Low Thermal Hysteresis

Potential applications at elevated temperatures require shape memory alloys (SMAs) to possess high transformation temperature, excellent shape recovery ability and thermal/functional stability. The present study investigated the influences of Dy addition on the microstructural characterization, functional behavior and possible deformation mechanisms in high temperature Ni54Mn25Ga21 SMAs. The results indicated that adequate Dy addition contributed to a desirable tradeoff among compressive strength, ductility and functional performance. Ni54Mn25Ga20.9Dy0.1 alloy showed the highest shape memory recoverable strain due to the improvement of mechanical properties and formation of small Dy-rich precipitates. Simultaneously, an obvious pseudoelasticity was observed over a wide temperature range with a maximum recoverable strain of 3.74% at 320°C in this alloy. All the Dy-containing alloys exhibited high thermal cyclic stability and quite low thermal hysteresis. However, it was revealed that a complicated and abnormal relationship between thermal hysteresis and the middle eigenvalue λ2 existed for the investigated alloys with a lattice transition from cubic to tetragonal. Calculated results based on energy minimization theory revealed that both the transformation strain and critical stress for inducing martensitic transformation varied with crystallographic orientations. The detwinning of pre-existing (112) compound twins and formation of (112) deformation twins were the dominant deformation mechanisms of martensite, which were highly compatible with the macroscopical recoverable strain. The present study provided valuable insights for developing high-performance multifunctional shape memory alloys for high temperature applications.

Effect of Dy addition on magnetocaloric effect in PrCo2 compound

The effect of Dy addition on the structure, magnetic and magnetocaloric properties of polycrystalline PrCo2 compound were investigated by x-ray diffraction (XRD) and magnetic measurements. The powder XRD patterns show that all the Pr1-xDyxCo2 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) samples are linear solid solutions with C15 cubic Laves phase and MgCu2-type structure. With the increases of Dy content, the lattice parameter decreases from 7.3090 Å for PrCo2 to 7.1914 Å for DyCo2, and the Curie temperature increases from 42 K (x = 0.0) to 151 K (x = 1.0). From the Arrott plots, the sample show the first order transition when 0.4 ≤ x ≤ 1.0. The magnetic entropy change of second-order PrCo2 compound is 10.7 J kg−1·K−1. And the magnetic entropy change of Pr0.6Dy0.4Co2 is the minimum of the whole system. After x ≥ 0.4, the magnetic entropy change value gradually increases, up to 10.4 J kg−1·K−1 for first-order DyCo2 compound. The RCP of these compounds was discussed.