Zr Binary System Research Articles

Rapid identification of highly glass-forming alloys in Cu–Zr binary system by laser glazing

The high-efficient experimental identification of novel metallic glasses with high glass-forming ability (GFA) is crucial for breaking through the traditional trial-and-error approach, which is time-consuming and costly. A rapid detection method for highly glass-forming alloys using laser glazing was introduced and validated in a classic binary Cu–Zr system with well-known GFA across a wide compositional range. The vitrification degree induced by laser glazing was assessed for each selected alloy and shows a strong correlation with GFA determined by traditional rapid solidification methods. The combination of experimental kinetic analysis and theoretical finite element simulation revealed possible thermodynamic mechanisms of glass formation and crystallization in the heat-affected zone (HAZ) formed by laser glazing. The results offer insights into not only the rapid identification method of highly glass-forming alloys using laser glazing but also the mechanism of glass formation under fast heating and cooling processes, providing guidance on the construction of bulk metallic glasses through laser additive manufacturing.

Shear strain rate sensitivity and crystallisation kinetics investigation in melt spun Cu64Zr36 binary metallic glass

Abstract Shear strain rate effect on crystallisation behaviour and characteristic temperatures of the three well-known glass formers in Cu–Zr binary amorphous system, namely Cu50Zr50, Cu56Zr44 and Cu64Zr36, were investigated. The crystallisation behaviour of Cu64Zr36 was uniquely found to be heavily dependent on shear strain rate. Crystallisation kinetics were studied through Isochronal transformation and isothermal transformation. The activation energy of crystallisation of each case was compared and contrasted. Johnson-Mehl-Avrami (JMA) analyses were also employed to study its kinetics behaviour. Finally, high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) combined with laser-assisted local electrode atom probe (LEAP) investigation revealed no detectable clustering or phase separation.

The forming mechanism and thermal stability of W-Zr super-saturated solid solution powder prepared by mechanical alloying

In this paper, W-33.3 at% Zr super-saturated solid solution powder was prepared by mechanical alloying, and its formation mechanism and thermal stability were systematically studied. After 30 h of milling, 33.3 at% of Zr was completely dissolved in W, and a super-saturated solid solution with BCC structure was formed. When the milling duration was increased to 50 h, the single BCC phase was transformed into a dual-phase mixture with a super-saturated solid solution and an amorphous phase. Thermodynamic calculations based on Miedema theoretical model suggested that the W-33.3 at% Zr binary system tended to form solid solution first and then transform into amorphous. Furthermore, high resolution transmission electron microscopy observation revealed that grain refinement, lattice distortion and dislocation may play an important role in the process of solid solution expansion and amorphization. Finally, thermal stability tests suggested that the prepared super-saturated solid solution powder has shown good stability at 800 ℃ for 2 h, which provides more possibilities for the application of W-Zr metastable alloy powders.

Exploration of the atomic-level structures of the icosahedral clusters in Cu–Zr–Al ternary metallic glasses via first-principles theory

The atomic-level structures of the icosahedral clusters in Cu–Zr–Al ternary metallic glasses were studied via the first-principles theory. The rules of icosahedra stability were determined. Icosahedra with a better chemical order or with a better symmetry exhibited a better stability. The strong connectivity between Al atom and Cu and Zr atoms was observed as demonstrated by the obvious degree of ‘bond shortening’. The Al atom contributed more to the structural stability when used as the central atom than the other atoms. Therefore, the addition of even a small amount of Al atom to the Cu–Zr binary system remarkably improved the stability of the icosahedron structures. The continued addition of Al atoms had a lower contribution to the improvement to the glass-forming ability of the Cu–Zr–Al alloys.

Thermodynamic modeling of Cr and Cr–H systems up to high temperatures and high pressures

A complete literature review of the thermodynamic and phase diagram properties of pure Cr and Cr–H system has been carried out. A thermodynamic assessment using the Calphad method has been accomplished up to 50 GPa for Cr including the liquid phase and up to 18 GPa on the Cr–H system using the most relevant literature data and our own ab-initio calculations. An up-to-date phase diagram of the Cr–H system is presented. Special attention was paid to the fcc phase to clarify the structure type (NaCl, hydrogen atoms located in the octahedral site of the fcc structure) and the composition (one hydrogen per chromium atom). The robustness of our proposed Cr and Cr–H models was demonstrated by comparing our measurements of pressure-composition isotherms of a bcc Cr–Zr alloy with the prediction made by combining the thermodynamic descriptions of the three Cr–H, H–Zr and Cr–Zr binary systems.

Microstructure correlation between eutectic and bulk metallic glass interpreted via dual-cluster formulas model

ABSTRACT It has been widely accepted that bulk metallic glasses (BMGs) are usually near deep eutectic compositions. However, the microstructure relationship between eutectic and BMG is still unresolved. The present work is devoted to revealing the atomic short-range-order microstructure similarity of eutectic and BMG. Principal cluster is defined according to atomic close-packing and degree of isolation and then dual-cluster formulas model [(principal cluster)1 + (principal cluster)2](glue atom)2, 4 or 6 is developed to interpret the eutectic and BMG composition, where the two principal clusters are derived from the eutectic-related phases. As a verification, deep eutectic and corresponding BMGs of Cu–Zr binary system are analysed. The study demonstrates that short-range-order microstructure correlation between eutectic and eutectic-type BMG is reflected by eutectic-related principal cluster. Meanwhile, a detailed procedure of design BMGs is established.

Effect of increasing Ti content on the phase, interface, dynamic mechanical properties and ballistic performance of W–Ti–Zr alloys

W2Zr intermetallic is an important reason for the brittleness of W–Zr binary system. When W–Zr alloys are used as the energetic fragment, the integrity of a projectile cannot be maintained under the explosion even propellant loading process, resulting in severe fracture of the projectile. Moreover, due to the strong atomic bonding in W2Zr intermetallic, the oxidation reactivity of the Zr atoms with oxygen in the air is significantly suppressed, limiting the effective energy release of W–Zr fragment under high-speed impacting process. In this study, based on the thermodynamic analysis, 30W-xTi-(70-x)Zr (wt.%) alloys were designed and prepared by powder metallurgy. It was found that the formation and stabilization temperature of W2Zr phase can be reduced by increasing the Ti content. The hard W-rich phase has changed from the coarse W2Zr particle to fine W2Zr precipitate and finally to the WTix solid solution with the increase of Ti content. Meanwhile, a semi-coherent interface between fine W2Zr precipitate and α matrix and even coherent interface between WTix and α matrix were formed, by which the intergranular fracture ratio between W-rich phases and α matrix was significantly decreased in the W–Ti–Zr alloys. Consequently, higher dynamic compressive strength and ductility of the W–Ti–Zr alloys were obtained by increasing the Ti content. The selected W–Ti–Zr alloys with high strength and proper failure strain exhibited good penetration and energy-releasing behaviors when they were used as reactive bullet launching at a velocity of about 1250 m/s. The relationship among the dynamic compressive strength, ductility and ballistic performance of the W–Ti–Zr reactive structural alloys was also discussed in detail.

Coupled Thermomechanical Responses of Zirconium Alloy System Claddings under Neutron Irradiation

Zirconium (Zr) alloy is a promising fuel cladding material used widely in nuclear reactors. Usually, it is in service for a long time under the effects of neutron radiation with high temperature and high pressure, which results in thermomechanical coupling behavior during the service process. Focusing on the UO2/Zr fuel elements, the macroscopic thermomechanical coupling responses of pure Zr, Zr-Sn, and Zr-Nb binary system alloys, as well as Zr-Sn-Nb ternary system alloy as cladding materials, were studied under neutron irradiation. As a heat source, the thermal conductivity and thermal expansion coefficient models of the UO2 core were established, and an irradiation growth model of a pure Zr and Zr alloy multisystem was built. Based on the user material subroutine (UMAT) with ABAQUS, the current theoretical model was implemented into the finite element framework, and the consequent thermomechanical coupling behavior under irradiation was calculated. The distribution of temperature, the stress field of the fuel cladding, and their evolution over time were analyzed. It was found that the stress and displacement of the cladding were sensitive to alloying elements due to irradiated growth.

Experimental investigation and thermodynamic assessment of the Mn–Zr system

The Mn–Zr binary system has been investigated via experimental measurements and thermodynamic calculations. In order to investigate phase equilibria in the Mn–Zr system, five alloys were prepared by arc melting under vacuum. All alloys were examined by means of X-ray diffraction, scanning electron microscopy and electron probe microanalysis after annealing at 650 °C for 70 days or 950 °C for 30 days. The homogeneity range of ZrMn2 was determined to be from 25.0 to 33.2 at.% Zr at 950 °C and from 26.7 to 34.3 at.% Zr at 650 °C. The solubility of Mn in (αZr) was 1.6 at.% Mn, while that of Zr in (αMn) was 0.2 at.% Zr at 650 °C. The invariant reaction temperatures of liquid → ZrMn2 + (βZr) and (βZr) → ZrMn2 + (αZr) were determined to be 1131 and 785 °C, respectively. A thermodynamic assessment of the Mn–Zr system was conducted by taking into account the present experimental results and reliable literature data. The calculated results using the presently obtained parameters can well reproduce the experimental data.

Heat capacity measurement of Zr2Fe and thermodynamic re-assessment of the Fe–Zr system

Critical evaluation of the Fe–Zr binary system has been performed based on the available experimental and calculated data. New experimental data on the heat capacity of Zr2Fe have been obtained using differential scanning calorimetry. Thermodynamic parameters have been optimized using the CALPHAD approach. New experimental results of specific heat capacity and ab-initio calculations for the ZrFe2, Zr2Fe and Zr3Fe intermetallic compounds have been taken into account in the optimization of the thermodynamic parameters. A self-consistent thermodynamic description of the Fe–Zr system has been obtained. Using the generalized “χ2”–criterion, the results calculated using the thermodynamic descriptions derived in the present work are compared with those previously published.

Studies on chain shuttling polymerization reaction of nonbridged half-titanocene and bis(phenoxy-imine) Zr binary catalyst system.

In this contribution, olefin block copolymers were produced via chain shuttling polymerization (CSP), using a new combination of catalysts and a chain shuttling agent (CSA) diethylzinc (ZnEt2). The binary catalyst system included nonbridged half-titanocene catalyst, Cp*TiCl2(O-2,6-iPr2C6H3) (Cat A) and bis(phenoxy-imine) zirconium, {η2-1-[C(H)=NC6H11]-2-O-3-tBu-C6H3}2ZrCl2 (Cat B), as well as co-catalyst methylaluminoxane (MAO). In contrast to dual-catalyst system in the absence of CSA, the blocky structure was obtained in the presence of CSA and rationalized from rheological studies. The binary catalyst system could cause the CSP reaction to occur in the presence of CSA ZnEt2, which yielded broad distribution ethylene/1-octene copolymers (Mw/Mn: 35.86) containing block polymer chains with high Mw. The presented dual-catalytic system was applied for the first time in CSP and has a potential to be extended to produce a library of olefin block copolymers that can be used as advanced additives for thermoplastics.

Experimental investigations and thermodynamic modelling of the Cr–Nb–Sn–Zr system

This work reports the Calphad modelling of the Cr–Nb–Sn–Zr quaternary system. In a previous paper, the thermodynamic modelling of the Cr–Nb–Sn system was presented. Since no experimental data were available for the Cr–Sn–Zr ternary system, new experimental data are provided, within this study, on the isothermal section at 900 °C. A ternary C14 phase has been identified on the Sn-poor side of the phase diagram. In addition to these experimental data, Density Functional Theory (DFT) calculations are carried out in order to determine formation enthalpies of the stable and metastable compounds. At last, the Special Quasirandom Structures (SQS) method is jointly used with DFT calculations in order to estimate the mixing enthalpies of the A2 and A3 binary solid solutions. Finally, these experimental and calculated data in addition to those from the literature, are used as input data for the Calphad modelling of the Cr–Zr, Nb–Zr and Sn–Zr binary systems and the Cr–Nb–Zr, Cr–Sn–Zr and Nb–Sn–Zr ternary systems. A complete database for the Cr–Nb–Sn–Zr quaternary system is provided.

Thermodynamic reassessment of the Al–Zr binary system

Based on the data of the literature reports, the Al–Zr binary system has been re-assessed thermodynamically through the CALPHAD (CALculations of PHAse Diagram) approach using Thermo-Calc software. The Redlich–Kister polynomials as well as the exponential temperature dependence model of Kaptay were used to describe the excess Gibbs energy of the liquid phase and the three terminal solid solutions: fcc_A1 (Al), bcc_A2 (βZr), and hcp_A3 (αZr). Additionally, the ten Al–Zr intermetallic compounds were treated as strict stoichiometric compounds. Finally, the comparison between the experimental and the two calculated phase diagrams, as well as the generated thermodynamic parameters, was critically discussed.

Measurement of interdiffusion and impurity diffusion coefficients in the bcc phase of the Ti–X (X = Cr, Hf, Mo, Nb, V, Zr) binary systems using diffusion multiples

The design and development of novel titanium alloys for structural and biomedical applications require reliable thermodynamic and kinetic databases. In this study, diffusion behaviors of six Ti–X (X = Cr, Hf, Mo, Nb, V, Zr) binary systems were systematically investigated at temperatures from 800 to 1200 °C using a set of five Ti–TiAl–Cr–Hf–Mo–Nb–V–Zr diffusion multiples. Concentration profiles of the six Ti–X binary systems were collected from binary regions of the diffusion multiples using electron probe microanalysis (EPMA). Both interdiffusion and impurity (dilute) diffusion coefficients in the Ti-rich bcc phase of these systems were extracted from the concentration profiles using the forward-simulation method. Twenty impurity diffusion coefficients of all the six elements in bcc Ti as well as Ti in bcc Zr at different temperatures obtained from this study are in excellent agreement with the literature data. The interdiffusion coefficients obtained from this study are also in good agreement with previous literature results. The large amount of new experimental data obtained from this study will be essential for establishing the mobility databases for the design and development of advanced titanium alloys.

Thermodynamic Database of the Phase Diagrams in the Sc-X Binary Systems

Sc-based alloys have been used as aero-structures materials, and Sc addition on wrought alloys has positive effects on weldability and welding properties. Phase diagrams play an effective role during the development of new type of alloy with good properties. Therefore, to establish the thermodynamic database of Sc-X binary systems is important and necessary.In the present work, the thermodynamic assessments of Sc-X (Ag, B, Cr, Er, Gd, Mo, Th, W, Y, Zr) binary systems was carried out by using CALPHAD (Calculation of Phase Diagrams) method based on the experimental data including thermodynamic properties and phase equilibria. The Gibbs free energies of the solution phases were described by the sub-regular solution model with the Redlich-Kister equation, and those of the intermetallic compounds were described by the sub-lattice model. A set of self-consistent thermodynamic parameters were derived for describing the Gibbs free energies of each solution phase and intermetallic compound. The calculated phase diagrams and thermodynamic properties are in good agreement with experimental data. The thermodynamic database of the Sc-X (Al, Ag, B, Ca, Co, Cr, Cu, Er, Fe, Ga, Gd, Ge, La, Li, Mg, Mn, Mo, Ni, Pb, Pd, Ru, Sn, Th, W, Y, Zn, Zr) binary systems have been developed, which can provide much important thermodynamic information for multicomponent Al-Sc based alloys.

Thermodynamic Assessments of the Sc-M (M: Cr, Gd, Mo, W and Zr) Systems

By using the calculation of phase diagrams (CALPHAD) method, the thermodynamic assessments of the Sc-M (M: Cr, Gd, Mo, W and Zr) binary systems were carried out based on the available experimental data including thermodynamic properties and phase equilibria. Gibbs free energies of the liquid, hcp and bcc phases in the Sc-M (M: Cr, Gd, Mo, W and Zr) binary systems were modeled by the substitutional solution model. An agreement between the present calculated results and experimental data was obtained.

Thermodynamic re-assessment of the Al–Gd and Gd–Zr systems

• The C15_laves phase Al 2 Gd was optimized to have a negligible homogeneity range. • Mixing enthalpy of Gd–Zr hcp phase was calculated by the first-principles method. • The inverse liquid miscibility in previous work was either reduced or eliminated. • Reasonable thermodynamic parameters were obtained for these two binary systems. Both Al–Gd and Gd–Zr binary systems were re-assessed using the CALPHAD (calculation of phase diagram) method to ensure a multi-component system containing them can be accurately described. Compared with previous assessments, the features of this work are reflected from the following aspects. Firstly, the C15_laves phase Al 2 Gd was treated as an intermetallic compound with a negligible homogeneity range using the two-sublattice model (Al, Gd) 2 (Al, Gd), meanwhile the liquid phase being described with the substitutional solution model. Secondly, first-principles calculations were carried out to provide theoretical information for optimization. The enthalpies of mixing of Gd 1− x Zr x ( x = 0.25, 0.5, 0.75) hcp_A3 solid solutions were calculated by applying the Special Quasirandom Structure containing 16 atoms (SQS_16). Finally, the inverse liquid miscibility appearing at high temperatures in previous studies was reduced for the Al–Gd system and eliminated for the Gd–Zr system. The calculated results for both binary systems reproduce the experimental and theoretical data satisfactorily, evidencing the reliability of the thermodynamic descriptions established in this work.

Thermodynamic assessment of the Al–Dy, Dy–Zr and Al–Dy–Zr systems

Like Al3Sc, the Al30Dy7Zr3 compound has an L12 structure, implying that it could probably be used to improve the strength of aluminum alloys at elevated temperatures. Thus, it is extremely important to understand the phase relations of the Al–Dy–Zr system in the Al-rich corner. Firstly, the phase diagram of the Al–Dy binary system was re-assessed with the C15_Laves phase treated as a stoichiometric compound. Then, using the special quasirandom structure containing 16 atoms (SQS_16) to simulate Dy1−x Zr x (x = 0.25, 0.5, and 0.75) hcp_A3 solid solutions, their enthalpies of mixing at 0 K were calculated by the first-principles method. Based on these results and the evaluated phase diagram in literature, the Dy–Zr binary system was optimized thermodynamically. Integrating the thermodynamic descriptions of the three constituent binary systems, the phase diagram of the Al–Dy–Zr ternary system in the Al-rich corner was optimized finally by coupling the first-principles calculation with the CALculation of PHAse Diagram method. A good agreement has been reached between the calculated phase relations and the experimental results, which indicates that the current thermodynamic description is reasonable.

Phase stability, elastic and electronic properties of Cu–Zr binary system intermetallic compounds: A first-principles study

First-principle calculations have been performed to investigate the structural, mechanical, thermodynamic and electronic properties of eight binary Cu–Zr intermetallic compounds. The results indicated that with increasing Zr concentration, the mass density decreases monotonously. All Cu–Zr intermetallic compounds considered here are mechanically stable structures, and they are ductile materials. Among the eight binary Cu–Zr intermetallic compounds, CuZr is the most ductile phase. Furthermore, the heats of formation of the Cu–Zr intermetallic compounds are negative. Furthermore, CuZr2 is a semiconductor with indirect band gap of 0.227eV, while the other seven Cu–Zr intermetallic compounds considered here are conductors.

Ir–Hf–Zr ternary refractory superalloys for ultra-high temperatures—Phase and microstructural constitution

A phase and microstructural evaluation of Ir–Hf–Zr ternary alloys with a composition below 30 mol% (Hf + Zr) was conducted by microstructural observation using scanning electron microscopy (SEM), composition analysis using electron probe microscopy analysis (EPMA), and phase identification using X-ray diffraction analysis (XRD). Partial isothermal sections of the Ir–Hf–Zr ternary system close to the Ir corner at 1800 °C and 2000 °C were determined. Research revealed that the f.c.c. and L12–Ir3(Hf, Zr) two-phase regions, which are shown in the Ir–Hf and Ir–Zr binary systems, were connected from the Ir–Hf side to Ir–Zr side in the Ir–Hf–Zr ternary system at Hf + Zr contents of less than 25 mol%. The L12–Ir3Hf and L12–Ir3Zr phases were fully soluble with each other. An Ir3(Hf, Zr)/Ir(Hf, Zr) two-phase structure was found in the Ir–15Hf–15Zr alloy with the Hf + Zr contents of 30 mol%. The potential of the Ir–Hf–Zr ternary alloys as ultra-high-temperature structural materials is discussed from the viewpoints of the microstructure and the lattice misfit between the f.c.c. and the L12 phases.