Laves Phase C15 Research Articles

Effects of Al variations on the microstructure and mechanical properties of laser-cladding AlxNbMo0.5Ti1.5Ta0.5Cr0.5 refractory high-entropy alloy coatings

Lightweight refractory high-entropy alloy coatings (RHEAcs) of AlXNbMo0.5Ti1.5Ta0.5Cr0.5 (where x = 0, 0.1, 0.2, and 0.3) were fabricated on 316L stainless steel surface by pre-placed powder laser cladding (LC) technology. The incorporation of Al element significantly enhanced the forming quality of coatings, resulting in nearly defect-free coatings with a thickness of 1.2–1.4 mm. Microstructural analysis revealed that the coatings were primarily composed of body-centered cubic (BCC) solid solution and C15-Laves phase. Due to the influence of a single brittle BCC phase, the Al-free coating exhibited high strength and brittleness, leading to numerous defects caused by thermal stress. The introduction of Al element refined the microstructure and facilitated the formation of Laves phases at grain boundaries, thereby alleviating stress to a certain extent. Consequently, the microhardness of the RHEAcs was significantly higher than that of the substrate, with the Al-free coating achieving the highest microhardness of 1250 HV, which was 5.89 times that of the substrate. Wear resistance results indicated that, prior to annealing, RHEAcs with varying Al content outperformed 316L stainless steel. Post-annealing, the coatings exhibited significantly lower friction coefficients compared with the annealed 316L substrate. The Al-free coating showed significant accumulation of abrasive particles, leading to severe abrasive and oxidative wear. Conversely, post-annealing oxidation induced the formation of dense and directional oxide accumulation, resulting in a notable improvement in wear resistance. Finally, the underlying strengthening mechanisms have been proposed and analyzed.

Preparation of a novel high-entropy alloy AlNbTiVZr with excellent strength and ductility: The effect of Zr composition on microstructure and properties

Light-weight refractory high-entropy alloys with low density and good ductility are widely used in various engineering fields. Despite their potential, achieving an optimal strength-ductility balance in these lightweight alloys remains an emerging field of study. In this study, Al0.8Nb0.5Ti2V2Zrx (x = 0, 0.3, 0.6, and 0.9) alloys were prepared by vacuum arc melting. A comprehensive evaluation of their microstructure, density, hardness, and compressive behavior at both room and 873 K temperatures was conducted. The introduction of Zr transforms the alloy phase structure from body-centered cubic (BCC) to BCC + C14-Laves. The areal fraction of the C14-Laves phase increased from 0 % to 32.47 % with increasing Zr content from x = 0 to 0.9, respectively. Furthermore, the Zr content had an obvious effect on the mechanical properties of the alloys. The compressive strength and hardness of the alloys improved, but the ductility simultaneously decreased, with increasing Zr content. The yield strengths of the alloys with x = 0, 0.3, 0.6, and 0.9 reached 971, 1216, 1483, and 1714 MPa, respectively, at room temperature, and 946, 1287, 1319, and 1469 MPa, respectively, at 873 K. In addition, the alloys maintained their deformation resistance and good ductility at 873 K. In particular, the Al0.8Nb0.5Ti2V2Zr0.3 exhibited a good balance between strength and ductility at room and 873 K temperatures due to the strengthening effect of a granular secondary phase. Upon comparison with other reported high-entropy alloys, the Al0.8Nb0.5Ti2V2Zrx series showcased superior specific yield strength and ductility.

Precipitation prediction and strengthening investigation of the non-equimolar TiVNbMoCr high entropy alloys

This study designed a series of TiVNbMoCr alloys under the VEC constraint. Based on the thermodynamic calculation, the precipitation behavior was predicted, and the precipitation strengthening was experimentally investigated and discussed. The results showed that below 600 °C, the designed alloys with VEC from 4.30 to 4.60 are metastable at a single β phase state. With low VEC, the HCP-structured α phase precipitates from the BCC-structured β phase with a coherent interface between them. With high VEC, TiCr2 (C15-Laves phase) precipitates from the β phase companying with the α phase. The prediction results are well consistent with the experimental results. Aged at 400 °C for 60 h, the alloys with VEC of 4.30 and 4.35 contained large volume fraction of the large-sized α phase, playing a great role in strengthening. The alloys with VEC of 4.55 and 4.60 exhibited small-sized precipitation particles acting in strengthening in terms of the Orowan mechanism, and the yield strength depends mainly on the volume fraction and size of precipitation particles, as well as the intrinsic strength of the β matrix that can be predicted by the Varvenne model based on the MD calculation. To some extent, the intrinsic ductility of the β matrix determines the tensile plasticity of the alloys with high VEC. Although favoring for strengthening, more TiCr2 precipitates are not conducive to tensile plasticity.

High-temperature lean Cu alloys with Cr-to-Nb atomic ratio of 2

Two Cu-Cr-Nb alloys, denoted as alloy 1 (comprising Cu-0.89 at% Cr-0.42 at% Nb) and alloy 2 (comprising Cu-1.84 at% Cr-0.99 at% Nb), were produced through a series of manufacturing processes including vacuum induction melting, melt spinning, consolidation, brazing, and baking, with both alloys aimed at achieving a nominal Cr-to-Nb atomic ratio of 2. Microstructural characterization using transmission electron microscopy and X-ray diffraction identified the cubic C15 Laves-phase Cr2Nb as the dominant precipitate in both alloys, cross-validated by thermodynamic calculations and atomistic simulation-based density functional theory (DFT). Besides cubic C15 Cr2Nb, hexagonal C14-phase Cr2Nb and α-BiF3 cubic structured Cr3Nb were also observed in the alloys, including a coherent interface formed between the Cr3Nb precipitate and the Cu matrix. The hardness of the alloys increases, and the electrical conductivity decreases with increasing alloying addition content; two practical equations described the trends. Further DFT simulations revealed that the electrical conductivity (conductance) of the Cu/Cr2Nb interface is an order of magnitude higher than the intrinsic Cu high-angle grain boundaries.

Investigation of the formation mechanism between β-NiAl and C14-Laves phases in laser additive manufacturing of nickel-based superalloy

The microstructure of laser additively manufactured nickel-based superalloy was analyzed using multi-scale characterization. The phase composition of the as-deposited sample was determined. The formation mechanisms of β-NiAl and C14-Laves phases were studied in depth. The crystallographic orientation relationship between the β-NiAl and C14-Laves phases was elucidated. The formation of the β-NiAl phase exacerbates the elemental segregation at the interface, leading to the generation of micro-strain and dislocations that provide nucleation sites for the C14-Laves phase. In addition, the effect of solidification rate on the precipitation of precipitated phases from the alloy was excluded. The present work contributes to understanding the precipitation behavior of β-NiAl and C14-Laves phases in nickel-based superalloys.

Designing eutectic medium-entropy alloys CoFeNiTax with outstanding mechanical properties

The eutectic medium-entropy alloys CoFeNiTax (x = 0.4, 0.5, 0.6) were designed successfully based on binary eutectic systems and thermodynamics calculations in this study. With the increase of Ta content, the solidified microstructures evolved from hypoeutectic to full eutectic and finally to hypereutectic. The primary phases in the hypoeutectic and hypereutectic were FCC solid solution and C14-Laves phase, respectively. The solidified microstructures were coarsened and spheroidized by the heat treatment, and a high-density of needle-like Laves phase precipitated in the FCC phase of the CoFeNiTa0.4. The crystallographic orientation relationship between the precipitated phase and matrix phase was [2‾ 42‾ 3]Laves//[011]FCC, and the crystal plane (1 1‾ 1)FCC was almost parallel to (0 1‾ 12)Laves, just with a mismatch angle of about 6°. The compressive strength and fracture strain of the heat-treated alloys were within 2232∼2465 MPa and 22.5–32.8 %, respectively, being superior to most high-entropy alloys. The excellent combination of strength and toughness was attributed to the synergistic effects of various strengthening-toughening mechanisms, including the second-phase strengthening, the solid solution strengthening, the interface strengthening and toughening, and the twinning toughening.

Hydrogen storage properties of Zr-based multicomponent alloys with C14-Laves phase structure derived from the Zr–Cr–Mn–Fe–Ni system

This study focused on assessing the crystal structure and hydrogen storage properties of two multicomponent alloys having the Zr33(CrMnFeNi)67 and Zr33Cr22Mn15Fe25Ni5 compositions. Both alloys were designed by thermodynamic calculations derived from the TiZrCrMnFeNi system after removing the titanium element from the original composition and keeping the high fraction of zirconium to explore new Zr-based compositions with a strong tendency to crystallize as a C14 Laves phase. The arc-melted Zr-based alloys exhibited a significant presence of C14 Laves phases and small amounts of NiZr intermetallic phase. Hydrogen storage properties investigated through pressure-composition-temperature (PCT) absorption and desorption isotherms revealed that the Zr33Cr22Mn15Fe25Ni5 alloy could absorb 1.8% (H/M = 1.2) of hydrogen with fast kinetics at room temperature after a simple heat activation, while the Zr33(CrMnFeNi)67 alloy could reversibly absorb 1.6% (H/M = 1) with equally fast kinetics. Zr-rich alloys exhibited a low hydrogen equilibrium pressure in the PCT isotherms. After full hydrogenation at room temperature, the initial metallic C14 Laves phases were converted to the respective Laves phase hydrides in both cases. Under cycling, the fractions of the secondary NiZr and the C14 phase change as the samples become more activated. The microstructural analysis, before and after the cycling, showed a very homogeneous microstructure and good distribution of the elements in both alloys.

Hydrogen storage properties of AB2 type Ti–Zr–Cr–Mn–Fe based alloys

This investigation explores the solid-state hydrogen storage properties of two series of hydrogen storage alloys: (Ti0.85Zr0.15)xMn0.8CrFe0.2 (x = 1.00∼1.10) and (Ti0.85Zr0.15)1.02MnyCr1.8-yFe0.2 (y = 1.00∼0.40) alloys. These alloys exhibit a single C14-Laves phase structure and demonstrate promising capabilities for solid-state hydrogen storage. The (Ti0.85Zr0.15)xMn0.8CrFe0.2 (x = 1.00∼1.10) alloys display an increased hydrogen absorption capacity and a reduced plateau pressure at higher super-stoichiometric ratios of x. When x = 1.10, the alloy achieves a maximum capacity of 1.86 wt%. The hydrogen storage capacity of the (Ti0.85Zr0.15)1.02MnyCr1.8-yFe0.2 (y = 1.00∼0.40) alloys diminishes as the value of y decreases. Furthermore, the hydrogen absorption plateau pressure and hysteresis factor of the alloys increase with an escalating Mn/Cr ratio. The analysis of cyclic stability reveals that the primary factor contributing to poor cycling stability of the (Ti0.85Zr0.15)1.02Mn0.4Cr1.4Fe0.2 alloy is the compositional decomposition, rather than pulverization or alterations in the phase structure.In summary, this investigation enhances our understanding of the solid-state hydrogen storage properties of these alloys. It establishes a foundation for further research and development in this pivotal field of hydrogen storage.

The Influence of Hydrogen on Structural and Magnetic Transformations in RMn2Hx Hydrides with Laves Phase C15 and C14 Structures—A Review

Laves phases crystallize in simple structures and are very common intermetallic phases that can form from combinations of elements throughout the periodic table, giving a huge number of known examples. A special feature of AB2 or AB5 phases is the ability to absorb hydrogen. This study attempts to collect, systematize and summarize the knowledge about RMn2Hx (R: Tb, Gd, Ho, Dy, Er, Sm, Nd and Y) hydrides available in the literature that is mainly related to structural and magnetic transformations. Due to the enormous wealth of data, the analysis focused on hydrides with x < 4.5 H/f.u., i.e., hydrides obtained at relatively low pressure (less than a few bars). The hydrides obtained in this way can be treated as potential hydrogen stores, which undoubtedly accounts for their current attractiveness.

The CrFeNbTiMox refractory high-entropy alloy coatings prepared on the 40Cr by laser cladding

In order to improve the performance of 40Cr coal mining cutter teeth, the CrFeNbTiMox (x = 0.2, 0.4, 0.6, 0.8, 1) refractory high entropy alloy (RHEAs) coatings were prepared on the 40Cr by laser melting. The effects of the Mo on the phase, microstructure, hardness, wear and corrosion resistance of the coatings were investigated. The results show that the coatings consist of BCC (Im3m), C14-Laves (P63/MMC), C15-Laves (Fd3m) and ordered B2 phase (Pm3m). The BCC phase increased and the C14-Laves phase decreased as the Mo element content increased. The central part of the coating is mainly composed of dendrites and some swelling crystals, the dendritic areas increase and the swelling crystals decrease with the increase of Mo elements. The Mo and Nb elements are mainly concentrated in the dendritic areas, and the Cr and Fe are enriched in the interdendritic areas. With the increase of the Mo element, the hardness of the coating increased from 676 HV to 841 HV, which is about 3.7 times higher than that of the substrate. Dry sliding friction and wear tests show that the wear resistance of the coating improves with the increase in Mo. The Mo1 coating has the lowest wear loss weight, wear volume and wear rate. In the 3.5 % NaCl solution, the polarization curves and the EIS fitting results show that the corrosion resistance of the coating improves with the addition of Mo elements. The hardness, wear and corrosion resistance of the 40Cr substrate is significantly improved due to the refractory high entropy alloy coating.

Spin order on the pyrochlore lattice: Magnetic crystallography, Landau thermodynamics and emergent phenomena

Pyrochlore sublattice is an integral structural component of numerous families of electronic and magnetic materials, including pyrochlores, spinels, and Laves phases C15, which exhibit plethora of magnetic behavior and multiple functionalities. The geometrical frustration inherent in the pyrochlore lattice leads to the formation of a broad diversity of unconventional magnetic states with unique physical properties. This article focuses on the symmetry-based concept of the Landau order parameter (OP) for uniform description of the most common types of long-range ordered magnetic structures (aristotypes) and related multi-ordered states derived from the pyrochlore lattice. Based on the combination of group-theoretical and crystallographic approaches the symmetry hierarchy of the magnetic structures and the corresponding OPs are established. The symmetry analysis reveals the role of the secondary OPs in the magnetic structure formation and emergent phenomena such as spin-driven ferroelasticity, ferroelectricity and orbital ordering. Within the framework of Landau thermodynamics, possible phase diagrams including multicritical points are determined. This study shows the significant potential of applying OP concept in a wide range of tasks, from the construction of microscopic theories to the search for new advanced magnetic and electronic materials.

Microstructure evolution and precipitation behavior in a Y2O3-bearing TiAl alloy during creep

The paper studies the microstructure stability of a Y2O3-bearing Ti–48Al–2Cr–2Nb alloy during creep. Tensile creep tests were performed at 800–850 °C under 100 or 275 MPa. Compared to thermal exposure, the low creep stress promotes the microstructure degeneration of lamellar colonies, mainly including α2-lath dissolution, γ-lath coarsening and βo phase precipitation. The high creep stress further accelerates the α2 → γ transformation, but goes against the precipitation of βo grains inside α2 laths. Similarly, more Cr-rich precipitates with the composition of Ti(Al, Cr)2 are observed in creep samples, which are identified as the C14-Laves phase. It has a {0001}C14//{111}γ and <101¯0>C14//<11¯0>γ orientation relationship with the γ phase. The high imposed stress also facilitates the precipitation behavior. It should be noted that there are a few C14-Laves phases precipitating along the Y2O3 interface by heterogeneous nucleation. The high strain energy around Y2O3 particles, especially under the high creep stress, contributes to the precipitation of C14-Laves phase not only at the Y2O3 interface, but also in the γ matrix.

Quasicrystalline clusters transformed from C14-MgZn2 nanoprecipitates in Al alloys

Ultrafine faulty C14-MgZn2 Laves phase precipitates containing quasicrystalline clusters and demonstrating the formation of binary quasicrystalline precipitates with Penrose-like random-tiling were observed in the over-aged FCC matrix of a commercial 7N01 Al-Zn-Mg alloy, using high angle annular dark field scanning transmission electron microscopy. The evolution from C14-Laves phase to quasicrystalline clusters is illustrated, and five-fold symmetry can be found in both real and reciprocal spaces. Our findings reveal the possibility of quasicrystalline formation from Laves phase in a highly plastic metal matrix like Al and demonstrate the structural relationship between Laves phase and quasicrystals.

Effect of V content on hydrogen storage properties and cyclic durability of V–Ti–Cr–Fe alloys

Vanadium-based body-centered-cubic (BCC) alloys are ideal hydrogen storage media because of their high reversible hydrogen capacities at moderate conditions. However, the rapid capacity decay in hydrogen ab-/desorption cycles prevents their practical application. In this work, V-based BCC alloys with three different V contents (V20Ti38Cr41.4Fe0.6, V40Ti28.5Cr30.1Fe1.4, V60Ti19Cr19Fe2, named as V20, V40, V60) were prepared by arc melting, and their microstructures and hydrogen ab-/desorption properties were investigated systematically. XRD results show that there is a number of C15-Laves phase presence in V20, which does not appear in V40 and V60. Meanwhile, the lattice constant of the BCC phase clearly decreases as the V content rises. These differences result in a hydrogen storage capacity of only 1.82 wt% for V20 alloy, but 2.13 wt% for V40 and 2.14 wt% for V60, and an increment in hydrogen ab-/desorption plateau pressure. The V40 and V60 alloys are chosen in de-/hydrogenation cycle test owing to higher effective storage capacities, and the results show that the V60 alloy has better cycle durability. According to the microstructural analysis of the two alloys during the cycles, the micro-strain accumulates, the cell volume expands, the particles pulverizes and the defects increase during the cycles, which eventually lead to the attenuation of the hydrogen storage capacity. The increment of the V content obviously improves the elastic properties of the alloy, which further diminishes the micro-strain accumulation, cell volume expansion, particle pulverization and defect increase, eventually resulting in a higher capacity retention and better cyclic durability.

Development of (Ti–Zr)1.02(Cr–Mn–Fe)2-Based Alloys toward Excellent Hydrogen Compression Performance in Water-Bath Environments

Three series of alloys, Ti0.92Zr0.10Cr1.7–xMn0.3Fex (x = 0.2–0.4), Ti0.92Zr0.10Cr1.6–yMnyFe0.4 (y = 0.1–0.7), and Ti0.92+zZr0.10–zCr1.3Mn0.3Fe0.4 (z = 0, 0.015, 0.04), were prepared by induction levitation melting for a metal hydride hydrogen compressor from 8 to 20 MPa at water-bath temperature, with investigation on their crystal structural characteristics and hydrogen storage properties. The results show that a single C14-Laves phase with homogeneous element distribution exists in all of the alloys. The hydrogen ab-/desorption plateau of the alloys is increased as the Fe, Mn, or Ti content increases due to decrement of the interstitial site radius originated from the respective atomic size. The hydrogen storage capacity of the alloys also correlates negatively with the hydrogen affinity of interstitial sites due to the influence of the element electronegativity. In a comprehensive consideration of the hydrogen storage performance for application, the Ti0.935Zr0.085Cr1.3Mn0.3Fe0.4 alloy shows saturated hydrogenation under 8 MPa at 293 K and dehydrogenation around 24.91 MPa pressure at 363 K with a hydrogen capacity of 1.74 wt %, as well as excellent cycling performance and mere hysteresis. The Ti0.92Zr0.10Cr1.0Mn0.6Fe0.4 alloy is another promising candidate with a remarkable hydrogen capacity of 1.86 wt % at 283 K and a dehydrogenation pressure of 27.94 MPa at 363 K, together with a satisfactory cycling durability. This study can guide the compositional design of AB2-type hydrogen storage alloys for hydrogen compression application.

Effect of Al on microstructure and mechanical properties of lightweight AlxNb0.5TiV2Zr0.5 refractory high entropy alloys

AlxNb0.5TiV2Zr0.5 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) refractory high entropy alloys were prepared by vacuum arc melting to obtain a lightweight REHA with excellent microstructure and mechanical properties. The microstructure, density, hardness, and compressive properties at room and elevated temperatures of AlxNb0.5TiV2Zr0.5 alloys were investigated. All AlxNb0.5TiV2Zr0.5 alloys are composed of the BCC phase and the C14-Laves phase, and the volume fraction of the Laves phase raises from 12.03% to 22.83% and then decreases slightly to 20.31% with the increase of Al content. The density of AlxNb0.5TiV2Zr0.5 alloys decreases with the increase of Al content from 6.12 g/cm3 to 5.43 g/cm3, and the microhardness increases from 397.2 HV to 641.9 HV. At room temperature, the yield strength of AlxNb0.5TiV2Zr0.5 alloys increases obviously at first and then decreases slightly with the range of 843 MPa–1727 MPa. The compressive strain of the alloys obviously decreases from 33.4% to 13.7% at first and then increases to 16.6%. Upon increasing the temperature to 873 and 1073 K, the strength of all alloys decreases, and the yield strength of the Al0.8 alloy remains 1569 and 1108 MPa, respectively. The compression ratios of all AlxNb0.5TiV2Zr0.5 alloys reach 50% without fracture at this temperature. The specific yield strength of Al0.8 alloy acheives 312 × 103, 284 × 103, and 199 × 103 MPa·cm3g-1 at 298, 873, and 1073 K, which is superior to that of other alloys. A strong correlation between the mechanical properties and the Al content of AlxNb0.5TiV2Zr0.5 alloys is observed. Al is one of the elements that can promote the formation of the Laves phase, and the volume fraction of the Laves phase increases with the increasing Al content. As a hard intermetallic compound phase, the mechanical properties of the alloys are improved with the increasing volume fraction of the Laves phase.

A lightweight Al0.8Nb0.5Ti2V2Zr0.5 refractory high entropy alloy with high specific yield strength

• The Al 0.8 Nb 0.5 Ti 2 V 2 Zr 0.5 alloy has a low density of 5.35 g/cm 3 and a high hardness of 5.86 GPa. • The alloy shows high yield strength at 298, 873, and 1073 K of 1418, 931, and 760 MPa, respectively. • The alloy shows high SYS at 298, 873, and 1073 K of 302, 245, and 154 kPa•m 3 kg -1 , respectively. A novel low density Al 0.8 Nb 0.5 Ti 2 V 2 Zr 0.5 refractory high-entropy alloy with dual-phase structure was prepared by vacuum arc melting. The microstructure is composed of BCC solid solution matrix phase and a few C14-Laves phase. The alloy has a low density of 5.35 g/cm 3 and a high hardness of 5.86 GPa. The compressive yield strength achieved 1418 MPa at room temperature and reached 931 MPa at 873 K and then dropped to 760 MPa at 1073 K. Compared with Inconel 718 superalloy and other refractory alloys, the specific yield strength at different temperatures and the density of the Al 0.8 Nb 0.5 Ti 2 V 2 Zr 0.5 alloy are more excellent.

Al2O3/MC particles reinforced MoFeCrTiWNb x high-entropy-alloy coatings prepared by laser cladding

ABSTRACT The Al2O3/MC particles reinforced MoFeCrTiW(Al2O3)0.5Nb x (x = 1, 1.5, 2, 2.5, and 3) high-entropy alloy coatings were successfully fabricated on the M2 high-speed steel by laser cladding. An investigation was carried out to assess the effect of the Nb on the microstructure and properties of coatings. The coatings are all composed of the BCC solid-solution phase, C14-Laves phase, and (Nb, Ti)C carbide plus a small amount of Al2O3. An increasing in Nb content results in the microstructural change from hypoeutectic to eutectic and the improvement in the hardness and wear resistance of the coating. When x = 3, the coating possesses the highest hardness (∼782 HV0.2) and lowest wear volume loss (∼0.52 mm3). The dispersion strengthening and lamellar boundary strengthening play a dominating role in enhancing the hardness and wear resistance of coatings.

Structure, mechanical stability, lattice dynamics and thermodynamic properties of C15-Laves phase Mg2Ce

A systematic study of the structure, mechanical properties, lattice dynamics and thermo-physical properties of C15-Laves phase Mg2Ce is performed through density functional theory (DFT) and density functional perturbation theory (DFPT). The optimized equilibrium lattice constant, equilibrium cell volume, bulk modulus and its pressure derivative reproduce perfectly the available experimental data and other calculated values. The individual crystal elastic constants and polycrystalline aggregates including the isotropic bulk modulus, shear modulus, Young's modulus, brittle/ductile characteristics, Poisson's ratio, Debye temperature and the integration of elastic wave velocities over different directions for C15-Laves phase Mg2Ce have also been evaluated up to 15 GPa using “energy-strain” method, the results indicate that C15–Mg2Ce is mechanically stable up to 15 GPa. Ideal tensile strengths (ITS) along three typical crystallographic orientations, and ideal shear strengths (ISS) in the (010)[101] slip direction of Mg2Ce have been explored by virtue of first principles total energy method. Additionally, both the density functional perturbation theory and the small displacement method are applied to determine the lattice dynamical stability and vibrational modes of Mg2Ce, it is predicted that C15-Laves Mg2Ce system is also dynamically stable up to 15 GPa. The microscopic symmetry properties of optical modes of Mg2Ce at the center of the Brillouin zone have also been analyzed with the combination of group theory. Numerous thermodynamic quantities in the temperature range 0–1000 K and the pressure range 0–15 GPa are obtained further based on quasi-harmonic approximation (QHA) and Debye model.

Plastic deformation of the CaMg2 C14-Laves phase from 50 - 250°C

Intermetallic phases can significantly improve the creep resistance of magnesium alloys, extending their use to higher temperatures. However, little is known about the deformation behaviour of these phases at application temperatures, which are commonly below their macroscopic brittle-to-ductile-transition temperature. In this study, we therefore investigate the activation of different slip systems of the CaMg2 phase and the occurrence of serrated yielding in the temperature range from 50°C to 250°C. A decreasing amount of serrated flow with increasing temperature suggests that solute atoms govern the flow behaviour when the CaMg2 phase is off-stoichiometric.