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In this study, we prepare Cr-doped Sb 70 Se 30 (SS) thin films via the magnetron sputtering. The influence of Cr doping on the crystallization behavior and structure characteristics of the SS thin films is systematically studied using a combination of experimental analyzes and theoretical calculations. The results reveal that compared with SS thin films, Cr-doped SS thin films exhibit higher crystallization temperature, better data retention capability, larger crystallization activation energy, and reduced resistance drift coefficient. In addition, the incorporation of Cr effectively suppresses grain growth in the SS thin films and refines the grain size. The electrical transport properties of the Cr-doped SS thin films are analyzed using a Hall system. Both X-ray photoelectron spectroscopy and first-principles calculations indicate that Cr is more prone to occupy Sb atoms and form stronger Cr–Se bonds, consequently enhancing the stability of the SS thin films. Raman spectroscopy confirms that the introduction of Cr leads to a decrease in bond length and an increase in bond energy. Moreover, the Cr-doped SS thin film exhibits minimal volume fluctuations and a smoother surface morphology, resulting in enhanced interface performance and reliability. Taken together, these results indicate that the introduction of Cr is an effective strategy for optimizing the properties and modifying the structures of SS phase-change materials. [ABSTRACT FROM AUTHOR]

The mechanical properties and ageing resistance of 0.5–10 mol% HfO 2 doped 3Y-TZP have been investigated. All samples were sintered at 1500 ◦C-2 h and characterized by density testing. Samples with polished surfaces were submitted to X-Ray diffraction (XRD) and microstructure testing and then cut into standards for 3-point bending testing. Group 2 was characterized by Vickers hardness and fracture toughness. Group 3 was accelerated ageing procession in autoclave condition containing at 134 °C and 0.2 MPa 10 h up to 40 h, and then detected by transmission electron microscopy (TEM) analysis. All sintered specimens presented nearly full densification. The grain size of 3Y0.5Hf-TZP was smaller than that of undoped 3Y-TZP after sintering. 3Y0.5Hf-TZP enhanced the bending strength by 34.6% compared to 3Y-TZP. The ageing kinetic parameter (n ∼ (0.66–1.64)) was related to the grain size and the ageing time from the onset of the transition until the transition reaches saturation. [ABSTRACT FROM AUTHOR]

MoCoB–Co cermets with varying Mo/B atomic ratios (AR Mo/B) and Co contents were fabricated, and their microstructure, mechanical properties, and corrosion behavior were investigated. The MoCoB hard phase exhibited the maximum grain size and anisotropy when the AR Mo/B was 0.84, which degraded the mechanical properties. For AR Mo/B ≥ 1.08, a third phase, Co 7 Mo 6 , and dense three-dimensional networks composed of stacking faults and ε-martensite plates were observed. These three-dimensional networks limited the dislocation slip in face-centered cubic γ-Co and ε-martensite, improving the hardness of the cermet and decreasing the transverse fracture strength (TRS). The corrosion resistance of the cermets was influenced by the MoCoB particle size, the Mo content of the binder phase, and the ε-martensite content. With an increase in the AR Mo/B , the corrosion resistance of cermets initially decreased and then increased. Additionally, as the Co content increased, the hardness gradually increased, whereas the TRS and fracture toughness steadily decreased. For AR Mo/B = 0.92 and a Co content of 45 at.%, the cermet displayed the best overall performance, with hardness, TRS, and fracture toughness values of HRA 89, 1720 MPa, and 13.2 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]

To develop tungsten-free cermets, a novel MoCoB–Co cermet composed of MoCoB as a hard phase and Co as a binder phase was synthesized by the reaction sintering of Mo, Co, and B powders. The microstructure evolution, phase transformation, and mechanical properties of the cermet were investigated. We demonstrated that the mixed powders experienced three solid-phase reactions, Co + B → Co 2 B, 11Mo + 15Co 2 B → Mo 2 Co 21 B 6 + 9MoCoB, and 4Mo + Mo 2 Co 21 B 6 → 6MoCoB +15Co, and underwent two liquid-phase reactions. Nanosized, tremella-like Co structures were formed on the surface of the particles between 1100 and 1200 °C. The formation of these structures may be due to the Kirkendall effect. Further, the first liquid, L 1 , was formed at 1242 °C by a eutectic reaction between the tremella-like Co structures and MoCoB. This led to an increase in the relative density of the sample from 43% to 71.7%. At 1268 °C, the second liquid, L 2 , was formed as a result of a eutectic reaction between Co and MoCoB that further increased the relative density of the sample to 95%. At 1300 °C, the cermet exhibited the highest hardness and transverse rupture strength of 83.9 HRA and 1700 MPa, respectively. [ABSTRACT FROM AUTHOR]

WCoB based cermets were prepared by spark plasma sintering at sintering temperature among 600°C-1200 °C. The phase evolution was investigated by detecting density behavior, phase composition, microstructure and mechanical properties during sintering process. The sintering process can be divided into three stages: powder densification, solid phase reaction and liquid phase sintering. WCoB hard phase forms at 1000 °C during solid phase sintering, showing better mechanical properties than Co 2 B, especially on Vicker's hardness. WCoB hard phase forms on the basis of Co 2 B binary boride and its content increases in liquid phase sintering stage with high density. The Vicker's hardness and transverse rupture strength (TRS) reach the maximum value of 1262 Hv and 1212 MPa at 1200 °C and 1170 °C, respectively. The fracture toughness reaches the maximum value of 21.8 MPa m1/2 at 1050 °C, and the inter-granular fracture is the main fracture mechanism. [ABSTRACT FROM AUTHOR]

The Mo–W–N and C–Mo–W ternary systems have been critically evaluated by means of the CALPHAD approach, wherein the C–Mo–W system was reassessed to ensure the model consistency. The Gibbs energies of individual phases in the ternary systems are described with corresponding models, such as substitutional solution model and sublattice model. A set of self-consistent thermodynamic parameters is obtained. Comprehensive comparisons between the calculated and reported phase diagram data show that the reliable information is satisfactorily accounted for by the present modeling. Based on the present work together with the previously reported assessments of C–Mo–N and C–W–N ternary sub-systems, a thermodynamic description of the C–Mo–W–N quaternary system is obtained and used to calculate the phase equilibria and thermodynamic stability of the hexagonal structured (Mo,W)(C,N) carbonitride phase. [ABSTRACT FROM AUTHOR]

The Ta–Mo–C system was assessed by means of the CALPHAD approach. All of the phase diagram and thermodynamic information available from the literature were critically reviewed. The liquid was modeled as substitutional solution phase, while the carbides including fcc-(Mo,Ta)C 1- x , bcc-(Mo,Ta), hcp-(Mo,Ta) 2 C and η-MoC were described by using corresponding sublattice models. The ζ-Ta 4 C 3- x was considered as a linear compound with carbon content fixed, while shp-MoC was treated to be a binary stoichiometric phase. There was no ternary compound reported in this system. The modeling of Ta–Mo–C ternary system covers the entire composition and temperature ranges, and a set of self-consistent thermodynamic parameters for the Ta–Mo–C system was systematically optimized. Comprehensive comparisons between the calculated and reported phase diagram and thermodynamic data show that the reliable information is satisfactorily accounted for by the present modeling. The liquidus projection and reaction scheme of the Ta–Mo–C system were also generated by using the present thermodynamic parameters. [ABSTRACT FROM AUTHOR]

The influence of N 2 atmosphere on the microstructure of gradient zone in Ti(C,N)-Mo 2 C-Ni cermet was systematically investigated by the coupling analysis of experimental characterization and thermodynamic calculation. Under the guidance of calculated carbon window, the composition of Ti(C,N)-Mo 2 C-Ni cermet was designed, and the cermet was produced via liquid-phase sintering at 1450 °C for 2 h under N 2 pressure of 20, 200, 400 and 600 mbar. The microstructure and element distribution of cermet were analyzed by using Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray spectroscopy (EDX). A homogeneous microstructure was obtained for cermet sintered in 20-mbar nitrogen atmosphere, whereas the thickness of gradient layer increased with nitrogen pressure. EDX mapping demonstrate that Mo and Ti are enriched in gradient zone, while Ni is lacking and partially segregated near the surface. The diffusion of elements in cermet is caused by the different nitrogen activity between surface and interior. The carbonitride grains show typical black core and gray rim structure in the bulk of cermets, while it present light-gray core and gray rim in the surface gradient layer. In addition, the Vickers microhardness measurement was performed for the gradient zone of cermets, and the hardness increased for cermets sintered in higher nitrogen pressures, which exhibit slower grain growth phenomena. [ABSTRACT FROM AUTHOR]

Highlights: [•] Using high velocity compaction we compact Cu–0.9Al2O3 composite powder. [•] At impact velocity 9.4m/s the relative green density was obtained 96.8%. [•] Axial and radial shrinkage increased with increase in sintering temperature. [•] The mechanical properties were improved with an increase sintering temperature. [Copyright &y& Elsevier]

Highlights: [•] Cholesterol (CL) was incorporated into pH-sensitive polymersomes. [•] The CL incorporation enhanced colloidal stability of the polymersomes. [•] The CL incorporation did not damage on pH sensitivity of the polymersomes. [•] CL-incorporating polymersomes played a role as an intracellular drug carrier. [Copyright &y& Elsevier]

Highlights: [•] Ti–10Mo alloy powder has been compressed by high velocity compaction technique. [•] Density of compacts depends on impact force per unit area of powder filled in die. [•] Maximum relative green density of the compacts was obtained 90.86% at 1615Nmm−2. [•] Spring back of compacts decreases with the increment of impact force. [•] Impact force per unit area affects the mechanical properties of the compacts. [Copyright &y& Elsevier]

Highlights: [•] Studying the W and Mo effect on the mechanical properties of Ti(C,N) cermets. [•] Studying the W and Mo effect on the electronic properties of Ti(C,N) cermets. [•] Distinguish the different property of hard phase and rim phase in Ti(C,N) cermets. [•] Explaining from theory the different property of Ti(C,N) and (Ti,Mo,W)(C,N) cermets. [ABSTRACT FROM AUTHOR]

Highlights: [•] We compacted Ti–6Al–4V powder by HVC technique. [•] As impact force rises up, the green density of the compacts increases gradually. [•] At impact force 1.857kN relative sintered density of the compacts reaches 99.88%. [•] Spring back of the green compact’s decreases gradually with increasing impact force. [•] Mechanical properties of the samples increases with increasing impact force. [ABSTRACT FROM AUTHOR]

A first-principles study on Ni-based superalloys is performed to estimate the properties of D0 22 structure Ni 3 X (Ni 3 Nb, Ni 3 Ta, Ni 3 V) phases and L1 2 structure Ni 3 Al phase with loading stress and high temperature. By stress-strain curve, the strength is higher in D0 22 structure Ni 3 X than in L1 2 structure Ni 3 Al. Loading stress causes systems unstable to increase decomposition tendency through calculating enthalpy and E above hull. The elastic properties reflect stress decreases system modulus and increases anisotropy. The lattice misfit is affected by stress and temperature. Loading stress increases lattice misfits of D0 22 structure Ni 3 X. Raising temperature decreases lattice misfit of each system. The effect on lattice misfit is larger in stress than in temperature. Ni 3 V can form negative lattice misfit with high temperature and low stress. Through overall comparison, the D0 22 Ni 3 V has advantages on high mechanical resistance, high thermodynamic stability, excellent elastic properties, negative lattice misfit in condition of high temperature and loading stress, which can be used to develop a new precipitation strengthening Ni-based superalloy. • First-principles to evolute stabilities of D0 22 Ni 3 X with stress and temperature. • Mechanical resistance is stronger in D0 22 Ni 3 X than in L1 2 Ni 3 Al. • D0 22 Ni 3 V has advantages on thermodynamic stability and lattice misfit. [ABSTRACT FROM AUTHOR]

Abstract: Micro powder injection molding (µPIM) differs from conventional powder injection molding (PIM) with respect to the effects of the mold dimensions. In this study, the rheological properties of the feedstock (mixture of carbonyl iron powders and binder) in molds with different diameters were analyzed by numerical simulation based on the powder-binder two fluid model. Viscosity, temperature, shear strain rate, velocity and the flow distance of the feedstock varied for different molds, but did not just reduce by proportion when the mold was smaller which would lead to many defects in green parts. The inner wall of the mold that was the key factor influencing the filling step in µPIM needed more studies. [Copyright &y& Elsevier]

Abstract: In this study, the hot deformation behavior of molybdenum was investigated by means of thermal simulation on a Gleeble-1500 machine. The experiments were carried out under different temperatures, ranging from 1100 to 1400°C, and with a strain rate of 1S−1 to 50S−1. The flow stress under the above mentioned hot deformation conditions was predicted using a back propagation (BP) artificial neural network. The architecture of the network included three input parameters: strain rate, temperature and true strain, and just one output parameter: the flow stress. One hidden layer was adopted, which include nine neurons. Compared with the prediction method of flow stress using the Zerilli–Armstrong model, the prediction method using the BP artificial neural network had higher accuracy. [Copyright &y& Elsevier]

Transition metal boride enable applications in fields of cutting tools as the hard phase, but their fabrication suffers from shortcomings in high temperature for binary and hard/soft phase balance. Here, we leveraged a WCoB-Co cermets prepared by using elemental powders of W, Co and B powders via in situ synthesis method and investigated the microstructure evolution of a composite structure of WCoB/Co. The phase evolution, microstructure evolution and mechanical properties were investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The complete sintering process consist of three solid-phase reaction stages and one liquid-phase sintering stage. The solid-phase reaction stage includes the following three reactions: B + 2Co → Co 2 B, 11 W +15 Co 2 B → 9WCoB + W 2 Co 21 B 6 , and 14 W + 2W 2 Co 21 B 6 → 12WCoB + 23Co + Co 7 W 6. The eutectic liquid phase, essential for the densification, forms at 1323 °C. The Rockwell hardness and density value reach 87.5HRA and 12.11 g/cm3, respectively. At 1380 °C, the traverse rupture strength (TRS) reaches the peak value of 1495 MPa. Moreover, the results show that transgranular fracture is the main fracture mode. The densification stage was completed at ~1400 °C. In particular, Co 7 W 6 phase was discovered during the study of the evolution of WCoB-Co cermets. An increase of the B content was found to be beneficial to eliminate the Co 7 W 6 phase that proved to be detrimental to mechanical properties. • WCoB-Co cermets were prepared using elemental powders. • The paper focuses on phase evolution and microstructure evolution. • Increasing the content of B element can improve the mechanical properties and eliminate Co 7 W 6 phase. [ABSTRACT FROM AUTHOR]

Currently, the lattice oxygen is the key factor affecting the thermal conductivity of AlN ceramics. In this paper, three methods are proposed to limit lattice oxygen, namely reducing the original powder oxygen content, changing the debinding atmosphere, and extending the sintering time. The results show that the low powder oxygen content and protective debinding atmosphere alter the carbon and oxygen content, and further promote the formation of the Y 4 Al 2 O 9 (YAM) phase. The generated YAM phase can effectively reduce the lattice oxygen in terms of thermodynamics. Prolonged high temperatures can provide kinetic conditions to reduce the lattice oxygen to 0.0343 wt%. In addition, morphological changes of the phase at the grain edges and their influence on the mechanical properties were noted. Finally, AlN ceramics with a thermal conductivity of 220 W m−1 K−1 and a flexural strength of 340 MPa were obtained. This study can provide a valuable reference for the industrial production of AlN ceramics. [ABSTRACT FROM AUTHOR]

The C-Co-Mo-W and C-Mo-Ni-W quaternary systems have been critically evaluated by means of the CALPHAD approach, in which the Co-Mo-W system was readjusted to ensure the model consistency. The thermodynamic models of Gibbs energies for individual phases in the ternary and quaternary systems are described, including substitutional solution model, sublattice model and linear compound model. The modeling covers the whole temperature and composition ranges, and a set of self-consistent thermodynamic parameters for the C-Co-Mo-W and C-Mo-Ni-W quaternary systems is obtained. According to the comprehensive comparisons between the reported and calculated phase diagram data, the reliable equilibria information is satisfactorily accounted for by the modeling. Based on the present work together with the previously reported assessments of binary, ternary and quaternary sub-systems, a thermodynamic database for the C-Co-Mo-Ni-W quinary system is constructed and applied to calculate the sintering region phase equilibria of the (W,Mo)C-(Co,Ni) cemented carbides. • Thermodynamic evaluations of C-Mo-W-Co/Ni quaternary systems are performed. • Reliable experimental data are well accounted for by the present modeling. • Calculated sintering region of (W,Mo)C-(Co,Ni) cemented carbides are presented. • The assessment is important to the design of (W,Mo)C-based cemented carbides. [ABSTRACT FROM AUTHOR]

The heat dissipation requirements of the new generation of semiconductors are placing higher demands on the overall performance of aluminum nitride (AlN) ceramics. This has led to an increasing emphasis on AlN ceramics that combine thermal conductivity and strength. AlN ceramics are often strengthened by hot-press sintering, but their thermal conductivity is typically modest. In this study, pre-sintering and annealing processes are introduced to optimize the thermal conductivity of hot-pressed AlN ceramics to avoid the detrimental effects of oxygen impurities in the AlN lattice. The effect of the oxide layer on the surface of commercial AlN particles is investigated, including density, phase composition, microstructure, and fracture behavior. The effect of annealing on the improvement of thermal conductivity and flexural strength is also verified. Electron paramagnetic resonance (EPR) analysis is performed to examine the concentration of intercrystalline defects under various conditions. Finally, AlN ceramics with a thermal conductivity of 204 W m−1 K−1 and a flexural strength of 376 MPa are obtained. [ABSTRACT FROM AUTHOR]

Highlights • The memory bearing can limit shear transfer in intermediate (immersion) joint of immersed tunnel. • The memory bearing was invented by trial-and-error tests of tearing metal rods. • The memory bearing enables the structure to fully utilize its capacity. Abstract The immersed tunnel in the Hong Kong–Zhuhai–Macao Bridge (HZMB) project has a deep alignment and poor geological conditions; the soft soil layer is up to 30-m thick. To protect the structure of the element joints of the immersed tunnel from differential settlement, we developed a special type of bearing that can be placed between the vertical shear keys of the element joints. These bearings 'remember' the maximum capacity that the tunnel structure can undertake so that they can guide the force flow from overloads via the tunnel structure to the foundation in the most appropriate manner to protect the shear-transferring structure while fully utilising it. As of now, all the element joints of the thirty-three elements in the HZMB tunnel are being protected with the bearings installed. This paper elaborates on our concept and experiments, based on which our design and applications were carried out. [ABSTRACT FROM AUTHOR]

MoCoB–Co cermets with different Mn contents were synthesized using an in-situ sintering reaction, and the effect of Mn addition on the microstructure, interfaces, and mechanical properties was investigated. The addition of Mn inhibited the transition of the binder phase from fcc to hcp. Adding an appropriate Mn can increase the density of the material and refine the hard phase grain. With increasing Mn content, the hardness decreased marginally and then gradually increased, and the transverse rupture strength (TRS) and fracture toughness (K IC) gradually decreased. The cermet with 6 wt% Mn addition had the smallest grain size and lower porosity. The hardness of the cermet increased from HRA 89.0 to HRA 91.7. The interface bonding strength of MoCoB/hcp-Co is higher than that of MoCoB/fcc-Co. After isothermal aging treatment, the content of hcp-Co in the binder phase increased markedly; thus, the K IC and TRS increased from 11.3 MPa m1/2 and 1200 MPa–13.3 MPa m1/2 and 1750 MPa, respectively. [ABSTRACT FROM AUTHOR]

A first-principles study was performed to assess the potential of MAB 2 (M = Nb, Ta; A = Co, Ni) ternary borides as friction-resistance cermet. The formation energy, decomposition energy, phonon dispersion curves and elastic constants were calculated to evaluate stabilities. The bulk modulus, shear modulus, Pugh's ratio, Poisson's ratio and elastic anisotropy were adopted to analyze elastic properties. The Debye temperature was used to reflect thermal conductivity. The density of states, charge density and Mulliken population were performed to reveal physical mechanisms. Through calculational results, MAB 2 possesses structure and mechanical stabilities, and then MAB 2 has excellent elastic properties. Both NbNiB 2 and TaCoB 2 are ductile materials; in addition, the thermal conductivity of NbNiB 2 and NbCoB 2 are satisfying. The calculations imply MAB 2 is a mixture of covalent, ionic and metallic bonds, indicating covalent bonds are vital. Especially, the theory hardness of NbCoB 2 , NbNiB 2 , TaCoB 2 and TaNiB 2 are 25.30, 27.71, 30.78 and 31.91 respectively, indicating MAB 2 has high-hardness potential. The comprehensive properties are more outstanding in MAB 2 than in MAB. The method from atomic scale to macroscale can accelerate optimization of novel friction-resistance cermet. • Studying the potential of MAB 2 -type borides as friction-resistance cermet. • Ratio of B in MAB 2 borides playing a vital role. • MAB 2 borides belonging to a mixture of covalent, ionic and metallic bonds. • Covalency mainly affecting properties of MAB 2 Borides. • Optimization way from atomic scale to macroscale. [ABSTRACT FROM AUTHOR]