Eutectic Compounds Research Articles

A Review of the Performance Improvement Methods of Phase Change Materials: Application for the Heat Pump Heating System

With the development of the economy and society, energy problems have become a great concern. The heat pump-coupled thermal energy storage (TES) system is a potential form of building heating, which can improve the stability of the grid and promote the consumption of renewable energy. Phase change materials (PCMs) are widely used in the field of building heating, but there are still some problems such as unsatisfactory melting points, low thermal conductivity, phase separation, and supercooling, which limit the application of PCMs in heat pump heating systems. Therefore, it is very important to improve PCMs by a performance improvement method. This work first summarizes the classification, advantages and disadvantages of PCMs, and introduces the connection between PCMs and heat pumps. Then, a detailed summary of PCMs applied in heat pump heating systems is presented, and a comprehensive review of the performance improvement methods for PCMs, which include additives, encapsulation, and eutectic compounds, is discussed. Finally, the existing problems, solutions, and future research directions are proposed. The emphasis of the research is to clarify the influence of PCMs on heat pump performance and the effect of different performance improvement methods on PCMs, and to illustrate the future development direction for PCMs in heat pump heating technologies, including the matching of heat pumps and PCMs, multi-standard decision methods and advanced control strategies.

Eco-friendly and economical preparation of permanent ferrite magnet with ultrapure magnetite concentrate: Focus on the action mechanism of silicon and aluminum impurities

In this study, ultrapure magnetite concentrate (UMC) was used to replace high-quality iron oxide red (IOR) for permanent ferrite magnet (PFM) preparation. UMC needs to be pre-oxidized to eliminate FeO which easily generates nonmagnetic phases in PFM. The magnetic powder and PFM products prepared with UMC and IOR had close magnetic properties, but the calcination temperature was lower and calcination time was shorter with UMC. Si and Al impurities in UMC could not only form eutectic compounds but also dissolve into the ferrite grain by substituting Fe. Those eutectic compounds benefited uniformity of grains by inhibiting grain overgrowth but decreased the purity of PFM because they were non-magnetic substances. Mn impurity in IOR entered into the ferrite grain by replacing Fe instead of participating in the formation of eutectic mixtures, while Cl impurity was evaporated during calcination, causing equipment erosion and environment pollution. UMC has the advantages of low raw material cost, good product property and non-pollution, and thus it has a broad application prospect in PFM preparation.

Глубокие эвтектические растворители в химическом анализе. Возможности и ограничения

Deep eutectic solvents (DES) are a mixture of two or more components, the melting point of which is significantly lower than the melting points of the starting materials. Environmental safety, ease of preparation in the laboratory, and low cost of DES have led to the fact that they have recently found increasing use in analytical chemistry. DES are most widely used in separation and concentration methods as effective extractants for the isolation of both hydrophobic and hydrophilic analytes from various objects of analysis. However, the possibility of their application is not limited to use only as extractants. This paper presents the classification of DES according to the criterion of their stability in the aqueous phase, the possibilities and examples of the separation of analytes from liquid, solid-phase and gaseous samples into the DES phase are also considered. In addition, various schemes for the implementation of liquid microextraction based on the principles of the formation and destruction of DES and methods for their automation based on the principles of flow methods are considered. The possibility of using eutectic compounds as effective dispersants in dispersive liquid extraction has been demonstrated. The possibility of simultaneous use of eutectic solvents both as extractants and as reagents for the derivatization of analytes to convert them into an analytical form directly in the extraction process, is shown. The possibility of modification of various sorption materials with eutectic solvents for the method of solid-phase microextraction, is shown. The paper touches upon the problems and limitations associated with the use of DES in chemical analysis, as well as the main prospects for its development.

Mechanical properties and microstructure of a high-quality Mg-Nd alloy ingot with large size manufactured by direct chill casting

In this work, a high-quality Mg-2.85Nd-0.25Zn-0.5Zr (wt%) alloy ingot with a diameter of 280 mm was successfully fabricated by direct chill casting. There was no obvious composition segregation along the radial direction of the ingot. The large temperature gradient along the radial direction, accurately the higher cooling rate in the surface, gives rise to both grain size and eutectic compounds fraction to gradually decrease from the center to the surface. This results in varying mechanical properties at different positions, such as higher strength and ductility in the surface than in other positions. The peak-aged alloy exhibited a higher strength-ductility synergy, with tensile strength of 282 MPa and elongation of 12.5%, than other Mg-Nd based alloys processed by permanent mold casting and sand casting. Furthermore, it is worth noting that the peak-aged alloy manifested significant strain hardening and high heat resistance, as evidenced by liner strain hardening at temperatures between 100 and 250 °C, which is mostly due to stable solute hardening triggered by the large atomic radius of Nd atoms in the α-Mg matrix. These findings provide references for the application and manufacture of large-scale magnesium alloy ingots. • A high-quality Mg-2.85Nd-0.25Zn-0.5Zr (wt%) alloy ingot with a diameter of 280 mm was successfully fabricated by direct chill casting. • The fraction of eutectic compounds increases and the grain size decreases from the center to the surface. • The alloy exhibited higher strength-ductility synergy than other Mg-Nd based alloys processed by permanent mold casting and sand casting. • The alloy showed abnormal strain hardening at high temperatures, rather than strain softening.

Deep eutectic solvents-based headspace single-drop microextraction for the chromatographic determination of phenols and aliphatic alcohols in atmospheric air

In this work, the possibility for gas chromatography determination of volatile organic compounds in atmospheric air with preliminary microextraction into single drop of a deep eutectic solvent is presented for the first time. Highly toxic compounds (phenol, o-cresol) and aliphatic alcohols (methanol, n-butanol, n-pentanol) were selected as analytes for which low MPCs in the atmospheric air were established. A eutectic mixture of natural, environmentally friendly substances menthol and thymol was used as an extractant. The resulting eutectic solvent forms a stable drop that allows the rapid extraction of analytes from the gas phase. 30 min of sampling is enough to achieve sensitivity at the level of maximum permissible concentrations of these analytes in atmospheric air. At the same time, the volatility of the components of the eutectic compound themselves made it possible to introduce this solvent directly into the gas chromatograph without dilution. The developed procedure was used to analyze real air samples and standard gas mixtures. The limits of detection for analytes were in the range 0.001–0.01 mg L−1. The RSD for all analytes was <5 %. This sample preparation method can be easily and efficiently combined with subsequent chromatographic detection.

Microstructure design to achieve optimal strength, thermal stability, and electrical conductivity of Al-7.5wt.%Y alloy

Aluminum-rare earth (Al-RE) alloys are being increasingly evaluated as new generation heat resistant conductor materials owing to their superior thermal stability, which is attributed primarily to the limited solubility of RE elements in the Al matrix and resulting RE-containing eutectic intermetallic compounds formed in their microstructure. This paper describes the main results from an experimental investigation into tailoring the contrasting strength-electrical conductivity characteristics of an Al–Y eutectic alloy by manipulating several microstructural features using multi-passes cold drawing and annealing processes. High strength of the alloy was achieved not only owing to substantial grain refinement, high dislocation density, and β-Al3Y intermetallic phases but also by forming stacking faults and inducing <111> fiber texture via cold drawing. The alloy was found to preserve fine grains in its annealed state, which is attributed to the β-Al3Y intermetallic phases at grain boundaries stimulating nucleation but also preventing grain growth. Moreover, <111> fiber texture and some stacking faults remained stable during annealing, while the β-Al3Y intermetallic phases spheroidized. As a result, the alloy exhibited extraordinary thermal stability with some loss of strength originating mainly from the reduction in dislocation density upon annealing. Importantly, the novel Al–Y wires exhibit superior heat resistance over the commercial Al–Zr wires. Finally, electrical conductivity of the Al–Y wires improved with annealing, which is primarily due to the release of interfacial energy accompanying spheroidization of β-Al3Y phases and underlying decrease in interfacial scattering at β-Al3Y/α-Al interfaces.

Eutectic intermetallic formation during solidification of a Mg-Sn-Al-Zn-Mn alloy

Multiple primary and eutectic intermetallic compounds (IMCs) often form during the solidification of multicomponent magnesium alloys. Here, we comprehensively explore eutectic intermetallic formation in Mg-4Sn-3Al-1.5Zn-0.6Mn (wt%) as-cast alloy, in comparison with Mg-3Al-1Zn-0.3Mn, to better understand Mg 2 Sn formation during complex multiphase solidification and how it affects the formation of other IMCs. Various IMCs formed at different stages of solidification: τ-AlMn and Al 8 Mn 5 early during solidification and Mg 2 Sn, β-Mg 17 Al 12, and τ-MgAlZn as late forming eutectic phases. Most Mg 2 Sn phase shared a faceted interface with β-Mg 17 Al 12 and τ-MgAlZn grains, forming a fully divorced eutectic particle containing multiple phases. EBSD-based trace analysis in combination with XCT and TEM results revealed that β-Mg 17 Al 12 and τ-MgAlZn phase grew adjacent to the {100} growth facets of Mg 2 Sn. Within multi-phase particles, seven types of reproducible orientation relationships (ORs) were measured between each intermetallic. The ORs between Mg 2 Sn and τ-MgAlZn were found to have the best lattice match among the observed phase pairs. For the defined ORs, Mg 2 Sn can be correlated with the icosahedral coordination in τ-MgAlZn. • Multi-phase eutectic particles investigated in a Mg-4Sn-3Al-1Zn-0.6Mn alloy. • β-Mg 17 Al 12 and τ-MgAlZn phase grew adjacent to the {100} growth facets of Mg 2 Sn. • Reproducible orientation relationships measured between eutectic intermetallics. • For the ORs, Mg 2 Sn correlated best with the icosahedral coordination in τ-MgAlZn.

Creep and Oxidation Behaviors of 25 wt.% Cr–Containing Nickel-Based Alloys Reinforced by ZrC Carbides

Three alloys based on nickel, rich in chromium due to their oxidation resistance at high temperature and containing ZrC carbides for their mechanical reinforcing against creep, were elaborated by foundry. After control of their as-cast microstructures, these alloys were subjected at 1100 °C to flexural creep and to oxidation in air. Script-like ZrC carbides were obtained in the interdendritic spaces, forming a eutectic compound with a part of the matrix. One of the alloys additionally contained Cr7C3 eutectic carbides. By comparison with a Ni–Cr–C reference alloy with similar contents in Cr and C, the three alloys demonstrated a much better creep resistance for the same conditions of stress and temperature. However, their oxidation rates were much greater than for the reference alloy. In contrast with the chromia-forming reference alloy, several kinds of oxides formed in the case of the three alloys, as NiCr2O4 spinel and oxides involving zirconium. A significant inward interdendritic oxidation progression was noticed for the three studied alloys. To benefit from the interesting creep resistance of these alloys for long sustainability in service, it appears necessary to significantly improve their oxidation behavior.

Green Designer Solvents for Boosting the Extraction of Biocompounds from Eugenia pyriformis Cambess Leaves

This work aimed at evaluating eutectic mixtures as green and designer solvents to extract bioactive compounds from Eugenia pyriformis Cambess (EPC) leaves. First, it was defined through the Folin–Ciocalteu (F–C) reducing capacity and antioxidant activity the optimized conditions of solid–liquid extraction (SLE). Consecutively, this condition (65 °C, 1:30 (m/v) solid–liquid ratio, and 150 min of process) was applied to evaluate the effect of the eutectic mixture-forming compounds in the SLE. The results showed that the lactic acid-based eutectic mixture was the most suitable solvent to preserve bioactive compounds from EPC leaves. Moreover, according to F–C analysis, the lactic acid-based eutectic mixtures boosted the SLE (163.14 ± 5.81 mg gallic acid/g sample). Regarding the phenolic profile, the EPC leaves showed the presence of quercetin, naringin, rutin, catechin, and gallic acid. These findings proved the eutectic mixtures and their forming compounds designer ability to extract valuable biocompounds from EPC leaves.

Role of interlayer composition in microstructure and mechanical properties during TLP bonding of GTD-111/IN-718 superalloys

An investigation was carried out to assess the applicability of transient liquid phase bonding of two dissimilar super-alloys with different interlayers. The effect of using three types of interlayer such as BNi-2, BNi-3, and BNi-9 on microstructure and mechanical properties was studied in the GTD-111/IN-718 system at 1100 °C for different bonding time. To determine the compositional changes and microstructure in the joint region, field emission scanning electron microscopy equipped with energy dispersive spectroscopy was utilized. The formation of Ni3B in the athermally solidified zone (ASZ) is controlled by the B content and, accordingly, the morphology of Ni3Si is governed by the Si content. The Cr content might impede the relocation of B from the interlayer into the base metal and the formation of CrB inside the ASZ is dominated by the Cr content. The high micro-hardness of the eutectic compounds is originated from the formation of boride matrixes such as Ni or Cr boride. The shear strength of the joint using BNi-9 after the completion of isothermal solidification is lower compared that that using BNi-3 and BNi-2, which could be related to the absence of Si in the filler metals constituent and the significant presence of Cr in BNi-9.

Investigation of microstructure evolution and strength mechanism of the Cu coated BNi-7 core-shell structure filler metal

In this paper, a novel method of using the Cu coated BNi-7 core-shell structured composite filler metals to braze was adopted to alleviate the residual thermal stress in the joints of Inconel 718. A pure Cu layer coated with the BNi-7 powders was successfully prepared by electroless plating to fabricate ductile filler metal with excellent mechanical properties. The obtained BNi-7 powders with 2 μm thick Cu coating exhibit dense and uniform structure through the elemental mapping analysis of the composite filler metal. The thickness and the content of the Cu layer could be determined by electroless plating time and the pH value of the plating solution. Meanwhile, the thermal physical parameters of the obtained composite filler were characterized by DSC analytical method, and the result indicated that the melting point was higher than the BNi-7 filler metal. The Inconel 718 were brazed without any defects using the composite filler metal in a vacuum. Compared to the BNi-7 filler metal, the Cu coated BNi-7 composite filler metal could form plenty of uniform reticular solid solutions during the high-temperature brazing process instead of acicular eutectic compounds. When adding the Cu powders mechanically into the original BNi-7 filler metals, voids and cracks could be found through the joints due to the uneven distribution of the Cu. The typical interfacial sequence of the joints was Inconel 718/Ni(Cu)ss+ σ-FeCr/Ni5P2 + Ni3P + Ni(Cr)ss + Ni2Cr + Ni(Cu)ss + σ-FeCr + Ni(Cu, Cr, Fe)ss/Ni(Cu)ss+ σ-FeCr/Inconel 718. The formation of the reticular Ni(Cu, Cr, Fe)ss phase released the stress in the brittle phase adjacent leading to the increasing ductility of the joints. The addition of the Cu-coated layer significantly enhanced the strength of the joint at room temperature, and the strengthening mechanisms were proposed.

New insights into microstructural changes during transient liquid phase bonding of GTD-111 superalloy

The effects of joining temperature (TJ) and time (tJ) on microstructure of the transient liquid phase (TLP) bonding of GTD-111 superalloy were investigated. The bonding process was applied using BNi-3 filler at temperatures of 1080, 1120, and 1160 °C for isothermal solidification time of 195, 135, and 90 min, respectively. Homogenization heat treatment was also applied to all of the joints. The results show that intermetallic and eutectic compounds such as Ni-rich borides, Ni−B−Si ternary compound and eutectic-γ continuously are formed in the joint region during cooling. By increasing tJ, intermetallic phases are firstly reduced and eventually eliminated and isothermal solidification is completed as well. With the increase of the holding time at all of the three bonding temperatures, the thickness of the athermally solidified zone (ASZ) and the volume fraction of precipitates in the bonding area decrease and the width of the diffusion affected zone (DAZ) increases. Similar results are also obtained by increasing TJ from 1080 to 1160 °C at tJ=90 min. Furthermore, increasing the TJ from 1080 to 1160 °C leads to the faster elimination of intermetallic phases from the ASZ. However, these phases are again observed in the joint region at 1180 °C. It is observed that by increasing the bonding temperature, the bonding width and the rate of dissolution of the base metal increase. Based on these results, increasing the homogenization time from 180 to 300 min leads to the elimination of boride precipitates in the DAZ and a high uniformity of the concentration of alloying elements in the joint region and the base metal.

MoSe2 monolayer crystallinity improvement and phase engineering for ultrasensitive SERS detection

Alkali metal halides (AMHs) interaction with metal oxide precursors has been demonstrated to be an exciting and reliable method in the deposition of several atomically thin layered materials since the reaction rate is considerably enhanced. Using three different AMHs (KBr, NaCl, and KCl), we assisted the synthesis of MoSe2 monolayers (MLs) in the atmospheric pressure chemical vapor deposition (APCVD) process in demonstrating that it is possible to improve the crystallinity of the MoSe2 flakes and to induce the formation of 1T domains in the 2H MoSe2 lattice that can be used to perform ultrahigh sensitive surface-enhanced Raman spectroscopy (SERS) detection. We observed that even though NaCl promotes the growth of large-sized MoSe2 MLs, we found critical photoluminescence (PL) quenching originated from forming a Na-O layer underneath the MoSe2 crystals. On the other hand, resonant Raman measurements show a prominent peak around 255 cm−1 only in KBr-MoSe2 single crystals originated from a double-resonant Raman process involving the ZA acoustic phonon and the C exciton, indicating optoelectronic-grade crystalline quality, thus explicating the higher PL emission in comparison with the other two AMH-assisted samples. KCl-MoSe2 X-ray photoelectron spectroscopy (XPS) and Raman spectra display features matching the structural properties of 1T-MoSe2 polyphase, confirming the existence of 1T domains embedded in the 2H-MoSe2 lattice. Moreover, thermogravimetric analysis (TGA) measurements show that the KCl-MoO2 mixture induces different sublimation processes compared with pure MoO2, probably producing potassium-rich eutectic compounds that could stabilize the 1T-MoSe2 domains. Finally, we demonstrate that the 1T-2H MoSe2 monolayers synthesized at 750 °C showed a significant surface enhance Raman scattering activity towards the Rhodamine 6G and Methylene blue, with a detection limit comparable with plasmonic surfaces.

Revealing joining mechanism in refill friction stir spot welding of AZ31 magnesium alloy to galvanized DP600 steel

The application of magnesium (Mg) inevitably involves dissimilar welding with steel. A novel solid state spot welding method, refill friction stir spot welding (refill FSSW), was utilized to weld AZ31 Mg alloy to galvanized DP600 steel. Although Mg/Fe is an immiscible alloy system, defect-free welds with high strength were successfully obtained in a wide parameter window. The results of microstructure, interfacial reactions, and mechanical properties are reported to reveal the underlying joining mechanism. Due to the melting of Zn coating and subsequent Mg-Zn reactions, Mg-Zn eutectic and intermetallic compounds were detected within welds. Heterogeneous interfacial reactions occur along Mg/steel interface, and the relationship between interfacial structure and fracture behavior was investigated. The joining mechanism is associated with Zn coating and Fe-Al layer: 1) the presence of Zn coating is beneficial for achieving high-quality welding between Mg and steel, it protects the interface from oxidation and contributes to brazing of the weld; 2) the Al present in Mg alloy reacts with Fe, resulting in the growth of Fe-Al layer, which contributes to the diffusion bonding in the interface. The overall results clearly show that refill FSSW is a competitive welding method for joining Mg and galvanized steel.

A novel severe plastic deformation method for manufacturing Al/Mg bimetallic tube

A new severe plastic deformation for manufacturing Al/Mg bimetallic tube called the TES (tube extrusion shearing) process, which combines direct extrusion with two-step shearing, has been developed to manufacture Al/Mg bimetallic tube. Load evolution with stroke at different temperatures has been simulated by establishing three-dimensional finite element simulation of the TES process of Al/Mg bimetallic tubes. To explore the deformation mechanisms of the Al/Mg bimetallic tube during the TES process, the microstructures and phase compositions and microhardnesses of the bonded layer have been observed and analyzed. A higher extrusion temperature would decrease the extrusion loads. Defects of bonding layer appear less if the extrusion temperature is higher, and the bonding layer of the bi-metal tube has better quality. Three eutectic compounds, Mg2Al3, MgAl, and Mg17Al12, can be formed in the interface transition zone. The average hardness of the bonding layer is very high. The results indicate that the TES process can produce large plastic deformation and manufacture Al/Mg bimetallic tube and improve the bonding layer.

Melting Characteristics of Coal Ash and Properties of Fly Ash to Understand the Slag Formation in the Shell Gasifier.

The flow temperature (FT) of the coal ash from the Liuqiao no. 2 mine in North Anhui Province (C00) is too high (∼1520 °C) to fit the Shell gasifier due to its relatively high content of SiO2 and Al2O3. To solve this problem, a series of coals were blended with C00 with different ratios, and the relations between FT and the ash composition were investigated. The coal ash was analyzed by X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy–EDX to elucidate the mechanism of the improved ash fusion performance and the slag formation in the waste heat boiler of the gasifier. It is shown that FT is relevant to the coal ash compositions as well as the structures formed at high temperatures. The existence of alkaline oxides (CaO, MgO, and Fe2O3) decreases the coal ash FT to a low level. The FT can decrease to <1350 °C to cater to the Shell gasifier by blending C00 and C03 with a mass ratio of 4:6 owing to the plentiful alkaline oxides in C03. The FTIR results indicate that the high flow temperature of C00 is attributed to the formation of mullite at high temperatures. The coal blending with various ratios changes the compositions of CaO, MgO, and Fe2O3, which can form some low-melting-point eutectic compounds with SiO2 and Al2O3 under high temperatures, inhibit the formation of mullite, and thus decrease the ash FT. The coal ash FT was found to have a good linear relation with the ash compositions, which can sever as a reference to the coal blending. According to the model parameters, it is shown that Mg has the most significant promoting effect on the decrease in FT of the coal ash. The caking tendency of fly ash increases with the rising Ca content and an excessive Ca-based fluxing agent used in the coal blending will lead to the aggregation of the Ca-rich clasts around the fly ash particle, resulting in the plugging of the waste heat boiler in the gasifier. Therefore, the Mg-based fluxing agent is more promising to improve the ash fusion performance and reduce the caking tendency of the coal fly ash.

Effects of solid solution treatment on microstructure and mechanical properties of SiCp/2024 Al composite: A comparison with 2024 Al alloy

The effects of solid solution treatment on microstructure and mechanical properties of SiC p /2024 Al matrix composite fabricated via powder thixoforming were investigated, as well as those of 2024 matrix alloy for comparison. The results indicate that the solution progress of the composite is more hysteretic than that of the alloy due to the obstacle role of SiC p to eutectic dissolution and grain coarsening. Interestingly, interface reactions of SiC p /2024Al, similar to those during fabrication, continuously occur during the solution treatment. Simultaneously, two constituents of the interface reaction layer, Al 2 Cu and MgAl 2 O 4 phases, change from the original agglomerated distribution to uniform distribution and finally to segregated form again accompanied by coarsening and phase transformation of Al 2 Cu into Al 2 CuMg. Such changes of the reaction layer significantly affect the interface debonding of SiC p /matrix or SiC p cracking during tensile test, and thus, the fracture regime and mechanical properties of the composite. The achieved modified shear-lag strengthening model by considering the strengthening effect of eutectic compounds can well interpret the strengthening mechanisms of these two materials, especially the variations of each strengthening mechanism contribution with solution time and the corresponding differences between these two materials. • The solution progress of SiC p /2024 Al matrix composite is more hysteretic than that of the 2024 Al alloy. • Interface reactions of SiC p /matrix still continuously operate during solution treatment. • The microstructure evolution of reaction layer plays an important role for mechanical properties of the composite. • The established strengthening model can well interpret the mechanical property variations of the two materials.

Separation and encapsulation of Persian red rose oil by eutectic compounds

In this work, the applicability of eco-friendly choline chloride-based deep eutectic solvents (DESs) in the extraction of β-phenylethyl alcohol (PEA) as the main ingredient of red rose oil from Iranian red rose blossoms have been investigated for the first time and the results were compared to the several conventional organic solvents including tetrahydrofuran (THF), n-hexane, cyclohexane, methyl ethyl ketone (MEK) and isobutyl alcohol (iBuOH). The Iranian red rose oil compositions were determined using the gas chromatography (GC) technique. The main compounds of Iranian red rose oil were PEA (63–69%), citronellol (10–11%), geraniol (8–9%), heptadecane (0.5–5%), nerol (4–5%), nonadecane (0.5–2.5%), methyl eugenol (2–3%), eugenol (2.5–3%) and benzyl alcohol (0.9–1.1%). The results indicate that choline chloride:sucrose DES with (1:2) mole ratio performs better in the extraction of PEA than the conventional solvents. The results were confirmed using Hansen solubility parameters (HSP) and the activity coefficient model. The extracted red rose oil was encapsulated for the first time in N-butyl palmitate/stearate (BPS) with a 24.6 °C melting point as the thermosensitive shell. The narrow particle size distribution of the produced nanocapsules of (70–550) nm were found.

Effect of microstructure aspects on mechanical properties of nanoparticle-assisted transient liquid phase (NP-TLP) joints for AZ31 alloy

To study the effect of nanoparticles on strengthening the transient liquid phase (TLP) joints of AZ31 alloy, different interlayers including pure copper, pure copper+TiO 2 nanoparticles, pure copper+Al 2 O 3 nanoparticles and pure copper+SiC nanoparticles were used. The pure copper was coated on the surfaces to be joined via electroplating. The samples were TLP bonded at 525 °C for 1 and 2 h under the pressure of 1 MPa, in an atmosphere-controlled furnace. After that, the microstructure of the joints were studied using optical and scanning electron microscopy and phase analysis as conducted using Energy-dispersive X-ray spectroscopy. The joints' shear strength was evaluated via a tensile test machine equipped with a special designed fixture and X-Ray Diffraction was utilized to analyze the related fracture surfaces. Microstructural studies showed that athermal solidification induced eutectic compounds at the joints were reduced with increasing bonding time and therefore, the isothermal solidification became more completed. This also increased the homogenity and uniformity of the microstructure and the joint's shear strength. The highest and lowest shear strength was observed for the joints made using pure copper+TiO 2 nanoparticles and pure copper+SiC nanoparticles-containing interlayers, respectively, about 90% and 15% of the base metal's shear strength. Also, the shear strength of the joints made using pure copper+Al 2 O 3 nanoparticles was higher for the 20 nm particles, compared to the 50 nm ones. • Exploring TLP bonding process for AZ31 alloy as an Mg-based one • Using nanoparticles-including interlayers with different materials and sizes • A reverse relationship between the nanoparticle size and joint's shear strength • Obtaining the highest joint's shear strength about 98% of that of the base metal • ASZ size and nanoparticles surface area as the factors of the joint's strength

The effect of bonding time on the microstructure and mechanical properties of dissimilar transient liquid phase bonding between UNS N08825 alloy and UNS S32750 super duplex stainless steel using the BNi-2 interlayer

• The dissimilar transient liquid phase (TLP) bonding of the UNS N08825 alloy to UNS S32750super duplex stainless steel was successfully accomplished using the BNi-2 interlayer. • The complete isothermal solidification occurred at 1050 °C and the bonding time of 300 s. • Shear strength of the TLP joints improved by increasing the holding time. In this study, the microstructure and mechanical properties of transient liquid phase, dissimilar joints between UNS N08825 alloy and UNS S32750super duplex stainless steel was investigated. The joining process was carried out at 1050 °C for 0, 60, 120, and 300 s using an BNi-2 interlayer. The transient liquid phase bonding area was divided into three zones: (i) the isothermal solidification zone which contained γ-Ni solid solution, (ii) the a-thermal solidification zone which consisted of Ni- and Cr-rich borides and Ni 3 Si precipitates, (iii) and the diffusion affected zone in which Cr-Ni-Fe-Mo-Cu-rich borides constituents existed. The hard and brittle eutectic compounds in the bonding zone posed deleterious effects on the mechanical properties of the joints. By increasing the holding time, the amount of these detrimental phases in the bonding zone decreased before finally a eutectic-free joint was achieved at the bonding time of 300 s, which was notably low as compared to the previous studies. The joint held for 0 s had the widest a-thermal solidification zone and the highest hardness was measured at the center of it (546 Hv). The average hardness of the diffusion affected zone on the UNS S3750 super duplex stainless steel side was approximately 450 Hv, which was markedly higher than that of the diffusion affected zone on the UNS N08825 side (302 Hv). The joint held for 0 s showed the lowest shear strength (239 MPa), while the maximum shear strength was obtained for the joint with a holding time of 300 s, approximately 487 MPa. Moreover, it was demonstrated that eutectic compounds were the principal cause of the brittle fracture in the joints containing the a-thermal solidification zone, whereas the joint with a complete isothermal solidification experienced a brittle fracture that occurred at the diffusion-affected zone of UNS N08825 alloy.