Solid Matrix Phase Research Articles

Buoyancy-driven nano-suspension subject to interstitial solid/nanofluid heat transfer coefficient: Role of local thermal non-equilibrium (LTNE)

BackgroundBecause of the prominent temperature discrepancy between fluid and solid in porous material, local thermal equilibrium (LTE) is not suitable in case of high-conductivity foams and electronic equipment. In view of above situation, Darcy-Brinkman-Forchheimer model subject to local thermal non-equilibrium (LTNE) is implemented. LTNE technique finds real world applications include groundwater pollution, geothermal extraction, microwave heating, industrial separation process, and transpiration cooling featuring with porous structure. The present study aims at the investigation of the entropy and hydrothermal characteristics of buoyancy-driven TiO2-H2O nanofluid inside a cross-shaped domain embodying two hot and cold rings influenced by LTNE. MethodsFinite element method (FEM) has been considered to solve the dimensionless form of governing equations. Significant findingsAmplification of interstitial solid/nanofluid heat transfer coefficient accounts for the intensification of streamlines, velocities, and diminution of isothermal lines in both nanofluid and solid matrix phases under the influence of LTNE. Strengthening of medium porosity whittles down entropy due to thermal effects in both nanofluid and solid phases, and that ameliorates entropy due to fluid friction and porous medium irreversibilities. Local and average Nusselt numbers in nanofluid phase reduce by 29.31 %, 20.72 %, 17.16 %, and 14.78 % while that in solid phase decays by 13.18 %, 7.63 %, 4.9 %, and 2.8 % for rise in εfrom 0.1 to 0.3, 0.3 to 0.5, 0.5 to 0.7, and 0.7 to 0.9, respectively. Introduction of Darcy-Brinkman-Forchheimer model subject to LTNE yielded better results in hydrothermal behavior of TiO2-H2O nanofluid inside a cross-shaped domain emplacing two hot and cold rings than earlier published results.

Multiscale modeling of diffuse damage and localized cracking in quasi-brittle materials under compression with a quadratic friction law

The diffuse damage and localized cracking of quasi-brittle materials (i.e., rocks and concretes) under compression can be delineated by a matrix-microcrack system, wherein a solid matrix phase is weakened by a large number of randomly oriented and distributed microcracks, and the macroscopic cracking is formed by a progressive evolution of microcracks. Several homogenization-based multiscale models have been proposed to describe this matrix-microcrack system, but most of them are based on a linear friction law on the microcrack surface, rendering a linear strength criterion. In this paper, we propose a new quadratic friction law within the local multiscale friction-damage (LMFD) model to capture the plastic distortion due to frictional sliding along the rough microcrack surface. Following that, a macroscopic Ottosen-type nonlinear strength criterion is rationally derived with up-scaling friction-damage coupling analysis. An enhanced semi-implicit return mapping (ESRM) algorithm with a substepping scheme is then developed to integrate the complex nonlinear constitutive model. The performance of LMFD model is evaluated compared to a wide range of experimental data on plain concretes, and the robustness of ESRM algorithm is assessed through a series of numerical tests. Subsequently, to effectively describe the localized cracking process, a regularization scheme is proposed by combining the phase-field model with the established LMFD model, and the discretization independent crack localization is numerically verified.

Microstructures and Corrosion Behaviors of Non-Equiatomic Al0.32CrFeTi0.73(Ni1.50−xMox)(x = 0, 0.23) High-Entropy Alloy Coatings Prepared by the High-Velocity Oxygen Fuel Method

The non-equiatomic Al0.32CrFeTi0.73(Ni1.50−xMox) (x = 0, 0.23) high-entropy alloy (HEA) coatings were prepared by the high-velocity oxygen fuel (HVOF) method. The microstructures and corrosion behaviors of the HVOF-prepared coatings were investigated. The corrosion behaviors were characterized by polarization, EIS and Mott-Schottky tests under a 3.5 wt.% sodium chloride aqueous solution open to air at room temperature. The Al0.32CrFeTi0.73Ni1.50 coating is a simple BCC single-phase solid solution structure compared with the corresponding poly-phase composite bulk. The structure of the Al0.32CrFeTi0.73Ni1.27Mo0.23 coating, combined with the introduction of the Mo element, means that the (Cr,Mo)-rich sigma phase precipitates out of the BCC solid solution matrix phase, thus forming Cr-depleted regions around the sigma phases. The solid solution of large atomic-size Mo element causes the lattice expansion of the BCC solid solution matrix phase. Micro-hole and micro-crack defects are formed on the surface of both coatings. The growth of both coatings’ passivation films is spontaneous. Both passivation films are stable and Cr2O3-rich, P-type, single-layer structures. The Al0.32CrFeTi0.73Ni1.50 coating has better corrosion resistance and much less pitting susceptibility than the corresponding bulk. The corrosion type of the Mo-free coating is mainly pitting, occurring in the coating’s surface defects. The Al0.32CrFeTi0.73Ni1.27Mo0.23 coating with the introduction of Mo element increases pitting susceptibility and deteriorates corrosion resistance compared with the Mo-free Al0.32CrFeTi0.73Ni1.50 coating. The corrosion type of the Mo-bearing coating is mainly pitting, occurring in the coating’s surface defects and Cr-depleted regions.

Influence of variable viscosity and local thermal non-equilibrium on nanofluid flow stability in an inclined porous channel

This study delves into the influence of local thermal non-equilibrium and changing viscosity on the stability of nanofluid flow in an inclined porous channel. The flow in the porous region governs Brinkman’s equation as well as a three-field model for temperature, with each field constitute the fluid, particle, and solid-matrix phases individually. Eigenvalue problem for a perturbed state is obtained using a normal mode analysis, and the problem is afterwards solved by the utilization of the Chebyshev spectral collocation method. Impact of various local thermal non-equilibrium parameters, critical Rayleigh number, and associated wavenumber are graphically displayed. Increasing values of the modified thermal capacity ratios, modified thermal diffusivity ratios, variable viscosity parameter, and channel inclination decrease the system’s stability for the interphase heat transfer parameter, which means these parameters destabilize the flow. Flow is most unstable when the channel is vertically oriented and the variable viscosity parameter ([Formula: see text]) = 0.5.

Advanced Polycrystalline γ′-Strengthened CoNiCr-Based Superalloys

Novel compositionally complex CoNiCr-based superalloys with excellent mechanical properties have been developed, which combine the multiprincipal element nature of high-entropy alloys with the precipitation strengthening in superalloys. A series of advanced polycrystalline γ′-strengthened CoNiCr-based superalloys, called CoWAlloys, with varying contents of Al, W, Ti, Ta, Mo, and Nb are investigated in terms of microstructure, thermophysical properties, yield, and creep strength. The microstructure of all CoWAlloys consists of an fcc solid solution matrix phase (approximate γ composition in at. pct: 50Co–20Ni–20Cr–10X (X = other alloying elements)), which is strengthened by a multicomponent γ′ (Ni,Co)3(Al,Ti,Ta,W,Nb)-based precipitate phase with a very high-volume fraction of around 60 vol pct (approximate γ′ composition in at. pct: 45Ni–30Co–25X). These alloys have high solidus temperatures above 1300 °C and moderate γ′ solvus temperature between 985 °C and 1080 °C leading to a large processing window. The increasing content of γ′-forming elements Ti, Ta, W, and Nb decreases this window, but increases the γ/γ′ lattice misfit and the anti-phase boundary energy, which contribute to a significantly higher yield and creep strength. Their properties are discussed in comparison with conventional polycrystalline Ni-base superalloys and so-called L12-strengthened high-entropy alloys, revealing that the creep strengths of the CoWAlloys are significantly higher. This is due to the reduced strain rate sensitivity of the CoWAlloys due to different underlying deformation mechanisms: By increasing the anti-phase boundary energy, a transition to stacking fault shearing and microtwinning occurs, which leads to the enhanced creep strength. Based on these results, guidelines and strategies for the design of next-generation advanced high-temperature polycrystalline superalloys are proposed.Graphical

Predicting stress and interstitial fluid pressure in tumors based on biphasic theory

The uncontrolled proliferation of cancer cells causes the growth of the tumor mass. Consequently, the normal surrounding tissue exerts a compressive force on the tumor mass to oppose its expansion. These stresses directly promote tumor metastasis and invasion and affect drug delivery.In the past, the mechanical behavior of solid tumors has been extensively studied using linear elastic and nonlinear hyperelastic constitutive models. In this study, we develop a two-dimensional biomechanical model based on the biphasic assumption of the solid matrix and fluid phase of the tissues. Heterogeneous vasculature and nonuniform blood perfusion are also investigated by incorporating in the model a necrotic core and a well-vascularized zone. The findings of our study demonstrate a significant difference between the linear and nonlinear tissue responses to stress, while the interstitial fluid pressure (IFP) distribution is found to be independent of the constitutive model. The proposed biphasic model may be useful for elasticity imaging techniques aiming at predicting stress and IFP in tumors.

A dual-phase CrFeNbTiMo refractory high entropy alloy with excellent hardness and strength

In order to the research of new type of coal mining machine cut-off tooth material, the CrFeNbTiMo high entropy alloy (RHEA) are studied and prepared. The microstructure is composed of BCC/B2 solid solution matrix phase and Laves phase. The alloy has a high strength of 785.26 MPa and a high hardness of 931 HV. In addition, the alloy also exhibits better ductility and strength under a split Hopkinson rod. The high strength and hardness of CrFeNbTiMo provides a new option for coal mining cut-off teeth.

INFLUENCE OF LOCAL THERMAL NON-EQUILIBRIUM ON THE STABILITY OF NANOFLUID FLOW IN AN INCLINED CHANNEL FILLED WITH POROUS MEDIUM

The effect of local thermal nonequilibrium on the stability of nanofluid flow in an inclined channel filled with a porous medium is numerically investigated. The Buongiorno model for nanofluid and Darcy-Brinkman model for flow in a porous medium are utilized, along with a three-field model for temperature, with each field representing the fluid, particle, and solid-matrix phases individually. The Chebyshev spectral collocation approach is used to determine the solution of the eigenvalue problem, which is obtained for perturbed states using a normal mode analysis. The impacts of various local thermal nonequilibrium parameters, the critical Rayleigh number, and associated wavenumber are displayed through graphs. It is worth noting that the LTNE parameters have a major impact on convective instability. Also, the dynamics of the flow field, behavior of temperature, and volume fraction are presented through streamlines, isotherms, and isonanoconcentration at the critical level.

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.

The hot compressive deformation behavior of cast Mg-Gd-Y-Zn-Zr alloys with and without LPSO phase in their initial microstructures

Samples of Mg-8.2Gd-3.8Y-1.1Zn-0.4Zr alloy with and without an intragranular lamellae-shaped long period stacking ordered (LPSO) phase were prepared through heat treatment and a series of hot compression tests on these materials were conducted to examine and evaluate the influence of LPSO on the hot compressive deformation behavior and deformation mechanisms at a given alloy composition. The values of activation energy for plastic flow (Q c ) of the solution treated (without LPSO phase) and annealed alloys (with intragranular LPSO phase) were larger than that for pure Mg, indicating that the presence of a high amount of rare earth (RE) elements and LPSO in the Mg matrix significantly increases Q c . The Q c value of the annealed alloy was larger than that of the solution treated alloy at all the strain levels (223.3 vs. 195.5 kJ/mol in average) and the largest difference in Q c between the two alloys was recorded at the smallest strain of 0.1 where precipitation of LPSO during deformation was limited in the solution treated alloy. These observations imply that the formation of LPSO phase out of the RE-rich solid solution matrix during deformation increases Q c , but the increment is not so large. Analysis of the hot compressive data of the alloys with LPSO phase and the alloys with RE-rich solid solution matrix in literatures indicates the similarity of the effect of the LPSO and RE-rich solid solution matrix phases on Q c and high-temperature strength.

Interfacial characterization and mechanical properties of additively manufactured IN718/CoNiCrAlY laminate

IN718/CoNiCrAlY multi-material laminates were prepared using laser powder bed fusion. The microstructure, phase composition, grain orientation, microhardness, and tensile properties of the multi-material were investigated. The results showed that the interface between IN718 and CoNiCrAlY was compact without cracks and had good metallurgical bonding. The interface was mainly composed of the γ-Ni(Co, Cr) solid solution matrix phase, β-NiAl intermetallic compound, and some η-Ni3Al0.5Nb0.5 precipitated phase. The microstructure of the interface along the building direction consisted of columnar dendrites with a strong (100) <001> cubic texture. A higher kernel average misorientation value was observed at the interface, indicating stress concentration, which was attributed to the intrinsic stress caused by the lattice differences between the two materials. The microhardness increased first and then decreased from IN718 to CoNiCrAlY along the building direction, and the hardness in the transition region was the highest (367.0 ± 3.7 HV). The ultimate tensile strength of IN718/CoNiCrAlY joint was 871.4 ± 13.0 MPa, which was lower than that of single IN718 and single CoNiCrAlY. Fracture analysis revealed that the multi-material specimen fractured in the transition region, and the fracture morphology was a mixed mode of cleavage fracture and micropore aggregation fracture.

Investigation on the Corrosion Resistance of Laser Cladding Fe-Based Alloy Coating Against Molten Zinc

In this paper, laser cladding technology was used to prepare an Fe-based coating on H13 steel substrate and its corrosion behavior in molten zinc was studied. The results show that a laser-cladding Fe-based coating can effectively protect the substrate from the corrosion of molten zinc, which is mainly related to its microstructure. The typical microstructure of the coating is composed of α-(Fe, Cr) solid solution matrix and CrFeB eutectic phases continuously distribute around the matrix. When molten zinc is in contact with the surface of the coating, it corrodes the α phase matrix preferentially and CrFeB eutectic phases with better corrosion resistance interweave with each other to form a three-dimensional skeletal structure that can play the role of diffusion barrier and slow down the diffusion rate of liquid zinc. The corrosion by molten zinc leads to the formation of a transition layer and an outer corrosion layer above the coatings. With the prolongation of the corrosion time, a large number of microcracks are generated inside the transition layer and fracture gradually occurs under the action of thermal stress. The partial spalling of the transition layer and the corrosion of α phase matrix occur at the same time, making the corrosion depth of the coating increase continuously. However, the dense corrosion layer above the coating and the dispersed boride fragments can still function as a barrier to the inward diffusion of molten zinc.

Effect of Local Thermal Nonequilibrium on the Stability of the Flow in a Vertical Channel Filled With Nanofluid Saturated Porous Medium

Abstract The stability of nanofluid flow in a vertical channel packed with a porous medium is examined for the local thermal nonequilibrium state of the fluid, particle, and solid–matrix phases. The effects of Brownian motion along with thermophoresis are incorporated in the nanofluid model. The Darcy–Brinkman model for the flow in a porous medium and three-field model, each representing the fluid, particle, and solid–matrix phases separately, for the temperature is used. A normal mode analysis is used to obtain the eigenvalue problem for the perturbed state, which is then solved using the Chebyshev spectral collocation technique. The critical Rayleigh number and corresponding wavenumber are presented graphically for the effect of different local thermal nonequilibrium parameters. It is noticed that the influence of local thermal nonequilibrium (LTNE) parameters on convective instability is significant.

A novel drying system – simultaneous use of ohmic heating with convectional air drying: System design and detailed examination using CFD

This paper introduces a novel drying system called ohmic assisted drying (OAD) – the simultaneous combination of ohmic heating and convectional air drying. The OAD system improved the drying characteristics of potato slices. Depending on the process conditions, drying time was shortened by 20–60% by OAD compared to conventional air-drying system. The level of applied voltage and air temperature were effective on drying time reduction. To achieve a better understanding of the changes in potato slices during OAD, a 3D mechanistic model was developed and validated with experimental moisture and temperature results. The model involves coupled heat, mass, momentum transfer as well as heat generation due to electrical current through the porous media. A non-conjugate, macroscopic, non-equilibrium modelling approach helps to define OAD process. Drying material (potato) consists of solid matrix, water, and gas phases, where pressure-driven flow, binary diffusion and phase change in drying volume were considered. The model predicts the spatial distribution of temperature, moisture, and pressure in the drying material. The prediction performance of the model is satisfactory especially in terms of moisture content since the standard error of estimate changes between 0.05 and 0.23. A deeper understanding is presented about the mechanisms of OAD highlighting strengths and weaknesses of the model and the drying system.

Comparative irradiation response of an austenitic stainless steel with its high-entropy alloy counterpart

Two metallic alloys in the quaternary system Fe–Cr–Mn–Ni were irradiated in situ within a transmission electron microscope (TEM) using Xe+ heavy ions in the temperature range of 293–873 K and in the regime of low- (30 keV) and medium-energies (300 keV) with respective maximum doses of around 40 and 140 dpa. The first alloy is the FeCrMnNi high-entropy alloy (HEA) synthesised with the alloying elements close to equimolar composition. The second alloy is a commercial austenitic stainless steel AISI-348 (70.5Fe-17.5Cr-1.8Mn-9.5Ni wt.%), selected as the “low-entropy” counterpart of the FeCrMnNi HEA. Microstructural characterisation was carried out in the TEM with in situ heavy ion irradiation to investigate the role of entropy on radiation induced segregation and precipitation (RIS and RIP). The results demonstrated that among all the irradiation cases investigated, the FeCrMnNi HEA had its random solid solution matrix phase preserved in 80% of the experiments whilst the austenite matrix of the AISI-348 steel underwent RIP in 80% of the cases. It is therefore demonstrated that small differences between two alloys can lead to different radiation responses, confirming the trend that, by tuning the elemental composition superior radiation resistance can be achieved in metallic alloy systems, but emphasising that some of the constitutive core-effects of HEAs are still in need of further confirmation especially when the application of HEAs in energetic particle irradiation environments is considered.

3D Printing of Liquid Crystal Elastomer Foams for Enhanced Energy Dissipation Under Mechanical Insult

Polymer foams are an essential class of lightweight materials used to protect assets against mechanical insults, such as shock and vibration. Two features are important to enhance their energy absorption characteristics: the foam structure and the matrix phase mechanical behavior. This study investigates novel approaches to control both of these features to enhance the energy absorption capability of flexible lattice foams. First, we consider 3D printing via digital light processing (DLP) as a method to control the foam mesostructure across a suite of periodic unit cells. Second, we introduce an additional energy dissipation mechanism in the solid matrix phase material by 3D printing the lattice foams with polydomain liquid crystal elastomer (LCE), which undergo a mechanically induced phase transition under large strains. This phase transition is associated with LC mesogen rotation and alignment and provides a second mechanism for mechanical energy dissipation in addition to the viscoelastic relaxation of the polymer network. We contrast the 3D printed LCE lattices with conventional, thermomechanically near-equivalent elastomer lattice foams to quantify the energy-absorbing enhancement the LCE matrix phase provides. Under cyclic quasi-static uniaxial compression conditions, the LCE lattices show dramatically enhanced energy dissipation in uniaxial compression compared to the non-LCE equivalent foams printed with a commercially available photocurable elastomer resin. The lattice geometry also plays a prominent role in determining the energy dissipation ratio between the LCE and non-LCE foams. We show that when increasing the lattice connectivity, the foam deformation transitions from bending-dominated to stretching-dominated deformations, which generates higher axial strains in the struts and higher energy dissipation in the lattice foam, as stretching allows greater mesogen rotation than bending. The LCE foams demonstrate superior energy absorption during the repeated dynamic loading during drop testing compared with the non-LCE equivalent foams, demonstrating the potential of LCEs to enhance physical protection systems against mechanical impact.

Multi-fracture interactions during two-phase flow of oil and water in deformable tight sandstone oil reservoirs

Tight oil reservoirs are complex geological materials composed of solid matrix, pore structure, and mixed multiple phases of fluids, particularly for oil reservoirs suffering from high content of in situ pressurized water found in China. In this regard, a coupled model considering two-phase flow of oil and water, as well as deformation and damage evolution of porous media, is proposed and validated using associated results, including the oil depletion process, analytical solution of stress shadow effect, and physical experiments on multi-fracture interactions and fracture propagation in unsaturated seepage fields. Then, the proposed model is used to study the behavior of multi-fracture interactions in an unsaturated reservoir in presence of water and oil. The results show that conspicuous interactions exist among multiple induced fractures. Interaction behavior varies from extracted geological profiles of the reservoir due to in situ stress anisotropy. The differential pressures of water and that of oil in different regions of reservoir affect interactions and trajectories of multi-fractures to a considerable degree. The absolute value of reservoir average pressure is a dominant factor affecting fracture interactions and in favor of enhancing fracture network complexity. In addition, difference of reservoir average pressures in different regions of reservoir would promote the fracturing effectiveness. Factors affecting fracture interactions and reservoir treatment effectiveness are quantitatively estimated through stimulated reservoir area. This study confirms the significance of incorporating the two-phase flow process in analyses of multi-fracture interactions and fracture trajectory predictions during tight sandstone oil reservoir developments.

Optical and electronic properties of CdTe quantum dots in their freezed solid matrix phase and solution phase

The present work deals with the comparison of sizes, optical and electronic properties of COOH functionalized CdTe quantum dots (QDs) in freezed solid polymeric (polyvinyl alcohol (PVA) matrix and in solution phase (water). PVA has been chosen as host material for guest CdTe QDs because of its unique properties like hydrophilicity, good thermo stability, and easy process ability. Experimental absorption, emission, X-Ray diffraction spectra and electronic band gap have been studied by UV–Vis absorption, luminescence and X-Ray diffraction spectroscopy. The smaller size of CdTe QDs in solid PVA polymer matrix (∼6 nm) and larger band gap of ∼9.5 eV validates their quantum confinement regime in freezed solid phase. The smaller particle size in solid phase compared to that of the particle size in its solution phase (8 nm) validates the non existence of agglomeration in solid phase. Appearance of high intense and wide luminescence emission in solid form proves the strong candidature of CdTe QDs as promising sensors for today’s optoelectronic and biomedical industry.

Numerical Simulation of Two-Phase System of “Combustible Liquid – Solid Fuel” Combustion in a Fixed Bed

Investigation of combustion of complex heterogeneous systems and particularly of twophase “combustible liquid – solid fuel” systems is topical because of the need to improve combustion of multicomponent and non-standard fuels as well as for resolution of specific ecological problems. The qualitative and quantitative peculiarities of combustion of two model combustible systems, notionally corresponding to the “sawdust – oil” and “wood chips – oil” mixtures are investigated numerically. The main peculiarity of the systems is volatility of the fluid component, being gaseous-flow driven inside porous media. A one-dimensional plain problem of combustion of compact layer with the ignition from the bottom and from the upper side is considered. It is demonstrated that due to low gas permeability of the fine-dispersed solid matrix (sawdust), air flow velocity is relatively low which results in slow formation of the combustion front (the characteristic time is tens of minutes). In case of coarse solid phase (wood chips), airflow rate is higher and corresponding time of temperature fronts formation is smaller (a few minutes). Both for the cases of fine-dispersed and coarse particles solid matrix phase, when set on fire from below, the fluid component is evacuated from the hot zone before the combustion front is formed. Since that, the main characteristics of the temperature front dynamics correspond to “dry” fuel system. In case of upper side ignition the combustion wave is formed at the time of the order of 100 s (when the used magnitudes of parameters are being used again), then it spreads downstream of the layer, accompanied by incomplete oxidation of solid fuel and complete combustion of oxygen. The effect of incomplete solid fuel combustion was noted earlier in the investigations of combustion of lean coal layer and some other systems. The velocity of the combustion wave propagation does not differ much for the cases of upper side and bottom side ignition. But the time of establishing the quasi-stationary velocity of the front to the steady-state value at the initial stage is much less in case of bottom side ignition. The results obtained by the authors can be utilized for optimization of multi-phase fuels combustion in compact layer, the regime parameters of in-situ combustion method of oil recovery increase as well as for improvement of some specific chemical processes.

Volume and size effects of intermetallic compounds on the high-temperature oxidation behavior of Mo-Si-B alloys

In this study, we investigated the high-temperature oxidation behavior of Mo-Si-B alloys with different volume fractions or sizes of intermetallic compound phases. Mo-Si-B alloys with uniformly dispersed intermetallic compound phases (Mo5SIB2 and Mo3Si) in Mo solid solution matrix phase were fabricated using a novel powder metallurgical route, as introduced in our previous study. An isothermal oxidation test was conducted at 1300 °C for up to 10 h. The high-temperature oxidation resistance of Mo-Si-B alloys improved by increasing the volume fraction of intermetallic compound phases; this was a result of the increased amount of protective oxidized layers, which protect the Moss phase from oxidation by covering the surface. In addition, Mo-Si-B alloy with smaller intermetallic compound phases pulverized by high-energy ball milling had better high-temperature oxidation resistance compared to Mo-Si-B alloy with as-synthesized intermetallic compound phases.