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The defects on TB6 titanium alloy were repaired using pulsed TIG（tungsten inert gas） additive manufacturing technology， and the effects of process parameters （pulse current and pulse time） and heat treatment on the microstructure and mechanical properties of the repaired TB6 titanium alloy were studied to determine the optimal heat treatment process parameters. The results show that the mechanical properties are relatively better in the as-repaired state when the pulse current is 50 A and the pulse time is 40 ms， with a tensile strength of 1113 MPa and an elongation of 5.26%. These samples are sequentially subjected to solid solution and aging heat treatment. When the samples are solid solution treated for 2 h under different temperatures （740， 760， 780 ℃）， the primary α phase is increasingly dissolved， while the β phase gradually grows and evenly distributes in the matrix. After water quenching， the growth of the β phase is inhibited， and acicular rhombic martensite α'' phase is precipitated in β grains， resulting in a decrease in tensile strength and a remarkable increase in elongation. Under different aging temperatures （500， 520， 540 ℃） for 8 h， the α'' phase continuously grows and gradually transforms to equiaxial grain， and the mechanical properties are greatly improved. The optimal microstructure and mechanical properties are achieved under the conditions of 780 ℃/2 h WC+520 ℃/8 h AC， with a tensile strength of 1119 MPa and an elongation of 7.36%.

Variable stiffness (VS) composite structures can significantly reduce weight by adjusting fiber orientation. However, in current designs, the directional properties of composites cannot be fully utilized due to the lack of comprehensive mechanical characterization of VS laminates. This paper aims to investigate the compressive and out‐of‐plane bending behavior of steered laminates. Firstly, the critical steering radius theory was studied and derived. Secondly, five steered laminates with different radii and one "baseline" laminate were designed, manufactured, and tested to examine the effects of fiber steering on compressive and interlaminar shear strength (ILSS). The results indicate that, compared to the "baseline" laminate, the steered laminates exhibit a decreasing trend in both compressive strength and ILSS, with the maximum reductions being 32.1% in compressive strength and 9% in shear strength. Meanwhile, the microstructure was observed to gain an in‐depth understanding of the changes in the mechanical properties of the steered laminates. This study comprehensively evaluates the mechanical performance of steered laminates and provides appropriate steering limits for the design and manufacture of VS structures. Highlights: The critical steering radius theory was studied and derived.Five steered laminates with different radii and one "baseline" laminate were designed, manufactured, and tested to examine the effects of fiber steering on compressive and ILSS.The microstructure was observed to gain an in‐depth understanding of the changes in the mechanical properties of the steered laminates. [ABSTRACT FROM AUTHOR]

Achieving the development of ultra-light Al–Li alloys with high strength and excellent corrosion resistance is always a challenge. In this study, the precipitation characteristics and electrochemical corrosion behaviours after isothermal aging of cast Al–Li alloys with two different Li contents were comparatively analysed. The results showed that the increase in Li content from 0.7 wt-% to 1.3 wt-% retarded the peak hardening and improved the Al–Li alloy hardness and strength by promoting the precipitation of the S′ (Al2CuMg) and T1 (Al2CuLi) phases. Besides, the galvanic coupling corrosion of the alloying element Cu with the aluminium matrix was reduced by more Li addition, thus improving the corrosion resistance of the alloy. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond compact (PDC) with different grain sizes were fabricated and the multi-physical behaviors, including mechanical-, thermal-, and magnetic performances, and the microscopic features were examined to study the grain size dependence of wear behavior while cutting dense granite. The results showed that the coarse grade PDC had higher impact resistance and fracture toughness. However, the fine grade PDC had higher cobalt content, hardness and thermal resistance. Among these properties, the wear resistance changed the same way as thermal expansion properties proving the strong correlation. Moreover, the crack network caused by thermal mismatch, and the peeling/fracture of metallic phases and diamond promoted fracture wear and played the critical roles in the wear of coarse grade PDC. [ABSTRACT FROM AUTHOR]

Application of the 316 L stainless steel (SS) is limited by its relatively low wear resistance, insufficient strength, and poor corrosion resistance in special environments. To this end, effects of Mo particles addition on the microstructure, mechanical properties, and corrosion resistance of the laser powder bed fusion (LPBF) 316 L SS are investigated in this study. The results show that the addition of Mo particles from 0 wt.% to 10 wt.% can modify the crystal orientation and improve the strength, wear resistance, and corrosion resistance of LPBF 316 L SSs. Particularly, the LPBF 316 L SS forms a biphasic structure with a similar ratio of α-Fe to γ-Fe with 5 wt.% Mo addition. As a result, the corresponding samples possess both the excellent toughness of austenitic SSs and the high strength and corrosion resistance of ferrite SSs, which reaches a high tensile strength of about 830 MPa, together with a low friction coefficient of 0.421 μ. Since the Mo particles addition is beneficial to increase the content of Cr2O3 on the samples surface from 13.48% to 22.68%, the corrosion current density of 316 L SS decreases by two orders of magnitude from 569 nA to 6 nA, while the mechanical properties remain favorable. This study is expected to serve as a reference for the preparation of LPBF SSs with excellent integrated performance. [ABSTRACT FROM AUTHOR]

Spark plasma sintering (SPS) is a new sintering method having shorter sintering time and higher densification speed than the traditional sintering methods. In this paper, the Si3N4/TiC ceramic tool material is sintered by SPS. The microstructure and mechanical properties of the material under different sintering parameters are compared. The sintering process of the material is then analyzed, and the best sintering parameters are obtained. Heat the material to 1600°C and keep the temperature for 15 min, then continue to heat to 1700°C and keep the temperature for 10 min, Si3N4/TiC ceramic tool material has high mechanical properties, its bending strength, fracture toughness, and Vickers hardness are 959 MPa, 8.61 MPa·m1/2, and 15.21 GPa, respectively. The scanning electron microscope (SEM) analysis shows that under this condition, the sintering additives and Si3N4/TiC material form the liquid phase, which makes the Si3N4 particles rearrange, dissolve, precipitate, and transform into rod shape β‐Si3N4. In addition, under the action of pulse current and external pressure, electric sparks are generated between TiC particles, which allows the material transfer and particle refinement. Therefore, the β‐Si3N4 has uniform grain size, and it is vertically and horizontally arranged in the structure, which makes the material have excellent mechanical properties. [ABSTRACT FROM AUTHOR]

Augite-based glass ceramics were synthesised using ZnO, FeO, and Fe2O3 as additives, and the spinel formation, matrix structure, crystallisation thermodynamics, and physicochemical properties were investigated. The results showed that oxides resulted in numerous preliminary spinels in the glass matrix. FeO, ZnO, and Fe2O3 influenced the formation of spinel, while FeO simplified the glass network. FeO and ZnO promoted bulk crystallisation of the parent glass. After adding oxides, the grains of augite phase were refined, and the relative quantities of augite crystal planes were also influenced. All samples displayed good mechanical properties and chemical stability. The 2wt% ZnO-doping sample displayed the maximum flexural strength (170.3 MPa). Chromium leaching amount values of all the samples were less than the national standard (1.5 mg/L), confirming the safety of the materials. In conclusion, an appropriate amount of zinc-containing raw material is beneficial for the preparation of augite-based glass ceramics. [ABSTRACT FROM AUTHOR]

Graphite ore and graphite tailings were blended into iron-tailings-based cementitious mortars, and their mechanical properties and microstructure were experimentally investigated. The flexural and compressive strengths of the resulting material were tested to compare the effects of graphite ore and graphite tailings as supplementary cementitious materials and fine aggregates on the mechanical properties of iron-tailings-based cementitious mortars. Additionally, their microstructure and hydration products were mainly analyzed using scanning electronic microscope and X-ray powder diffraction techniques. The experimental results showed that the mechanical properties of the mortar material incorporating graphite ore were reduced due to the lubricating properties of graphite ore. As a result, the unhydrated particles and aggregates were not tightly bound to the gel phase, making the direct application of graphite ore in construction materials unfeasible. In the iron-tailings-based cementitious mortars prepared in this work, the optimal incorporation rate of graphite ore as a supplementary cementitious material was 4 wt%. The compressive strength of the optimal mortar test block after 28 days of hydration was 23.21 MPa, and the flexural strength was 7.76 MPa. The mechanical properties of the mortar block were found to be optimal with a graphite-tailings content of 40 wt% and an iron-tailings content of 10 wt%, resulting in a 28-day compressive strength of 48.8 MPa and a flexural strength of 11.7 MPa. By observing the microstructure and XRD pattern of the 28-day hydrated mortar block, it was determined that the hydration products of the mortar with graphite tailings as an aggregate included ettringite, Ca(OH)2, and C-A-S-H gel. [ABSTRACT FROM AUTHOR]

To solve the problems that ceramic tools were sensitive to cracks, ZrSi2 crack repairing agent was added into Si3N4/TiC ceramic tool material matrix, which made ceramic tools have crack repairing ability. When ZrSi2 content was as 10% (volumn fraction), Si3N4TiC/ZrSi2 ceramic tool materials had better comprehensive properties, with flexural strength of 815 MPa, fracture toughness of 8.06 MPa ⋅ m1/2, Vickers hardness of 15.91 GPa and relative density of 99.72%). Cracks were introduced into the surface of ceramic tool materials by Vickers hardness tester, and the optimal repair parameters and repair mechanism of cracks in Si3N,/TiC-based ceramic materials with ZrSi2 as repair agent, were studied. The research shows that the flexural strength of Si3N4TiC/ZrSi2 prefabricated crack specimen with 10%) ZrSi2 added may be restored to 92.02%) of that of smooth specimen after heat treatment at 800 °C for 60 min in air atmosphere, and the crack with the surface length of 300 ~ 350 µm is completely repaired, and an oxide layer mainly composed of ZrO2 and SiO2 is formed on the surface of the specimen. The mechanism of crack repair of ceramic cutting tool materials is analyzed as follows-, in the air heat treatment processes, ZrSi2, a healing agent at the crack and the surface of the material, preferentially reacts with oxygen to generate ZrO2 and SiO2, which heal the crack on the surface of the material and restore the strength of the crack sample. At the same time, during cutting, ZrO2 and SiO2, oxidation products of ZrSi2 at the cracks and material surfaces, may repair the crack in time and improve the wear resistance of the tool. [ABSTRACT FROM AUTHOR]

Thin-wall samples of 17-4 PH stainless steel were prepared by pulsed TIG wire arc additive manufacturing technology (P-TIG WAAM), and the microstructure and mechanical properties of the samples in different regions (bottom, middle, top) were studied. The results show that the microstructure of the thin-wall samples are mainly consisted of martensite matrix embedded by worm-like (bottom) and strip-shaped (top) δ-ferrite, with a small amount of austenite. The δ-ferrite content gradually decreases along the building direction, resulting in a gradual increase in microhardness from the bottom to the top. Along the building direction, the precipitation density and size distribution of nano-scale CRPs (Cu-rich precipitates) in δ-ferrite and martensite, as well as at the δ-ferrite/martensite interface are significantly different: the CRPs in δ-ferrite is precipitated with lower density, larger size, and inhomogeneous distribution at the bottom region, while that in martensite is precipitated with higher density, smaller size, and homogeneous distribution. At the bottom region, a chain of large size fcc-CRPs (∼65 nm) is precipitated along the δ-ferrite/martensite interface to coordinate the strain between them and improve the strength and ductility simultaneously, thus excellent mechanical properties (tensile strength = 1356 ± 24 MPa, elongation = 15.16 ± 2.6 %) are obtained. The relationship between the evolution of CRPs and the intrinsic heat treatment (IHT) during P-TIG WAAM is also discussed. [ABSTRACT FROM AUTHOR]

Due to the development of advanced packaging technology such as Package on Package (POP), traditional Sn-Ag-Cu (SAC) solder can no longer meet the demand. Utilizing the differences in temperature and performance of various solder materials to create composite structures for soldering is an effective method to achieve PoP interconnection. In this research, the microstructure of the interface between SAC305 and liquid in the incomplete dissolved solider ball was observed, and the grain orientation after solidification was analyzed. In addition, the effect of SnBi ratios on the microstructure and mechanical properties of SAC305-SnBi composite solder balls, and the fracture mechanism was analyzed according to the fracture morphology. The results show that according to Electron Backscatter Diffraction (EBSD) analysis, the grain size of Sn-Ag-Cu-Bi is small, and the orientation tends to be the same. With the rise in SnBi content, the eutectic structure in the solder ball exhibited a progressive increase and the IMC at the interface gradually changed from uneven rod-like structure to more uniform scallop-like structure. When the weight fraction of SnBi is 66.7%, the shear strength researches a maximum value of 62.2 MPa. As the SnBi content increases, there is an observable shift in the fracture location from the IMC to the solder. • The differences in temperature and properties of SnAgCu and SnBi solders are exploited to create composite structures for soldering. • The microstructure of the interface between SAC305 and liquid in the incomplete dissolved solider ball was observed, and analyzed the grain orientation after solidification. • The effect of SnBi ratios on the microstructure and mechanical properties of SAC305-SnBi composite solder balls, and the fracture mechanism was analyzed according to the fracture morphology. [ABSTRACT FROM AUTHOR]

A novel Fe/Cu interface with excellent mechanical properties in a magnetic yoke was fabricated by friction stir welding. This method eliminated defects that commonly form during conventional bead welding. The thick oxidisation layer at the Cu/Fe surface that formed due to fusion welding was eliminated during friction stir welding (FSW). Combined with the severe deformation introduced by FSW, the Cu/Fe interface obtained by fusion welding was hardly distinguishable due to mutual embedding at the Cu/Fe interface. The in situ digital image correlation analysis indicated that this Cu/Fe interface reconstruction also modified the deformation and crack propagation behaviours. The tensile load and displacement of the joint by FSW were remarkably improved while maintaining magnetic isolation. [ABSTRACT FROM AUTHOR]

Summary: The effects of enzymolysis with four different enzymes on the free amino acid content (FAA) and protein subunit composition (SDS‐PAGE) of chickpea milk, as well as the rheological behaviour, microstructure and aroma volatile compounds of fermented chickpea milk (FCM), were investigated. After enzymatic catalysis, 7S and 11SA globulin were all slightly degraded and a certain amount of free amino acids could be released. Moreover, FCM with enzymolysis possessed lower elastic modulus (G′) and viscous modulus (G″) than FCM. The SEM micromorphology and rheological characteristics of FCM hydrolysed with papain (C1 FCM) were substantially improved. Principal component analysis (PCA) results grounded on E‐nose can distinguish the flavour changes in FCM with enzymolysis to some extent. Totally, sixty‐six volatile aroma compounds were detected by GC‐MS. The varieties of volatile aroma compounds in C1 FCM (41) were more than that in FCM (24). These findings indicated that enzymolysis, especially with papain, could be used as an effective method to improve the structure, rheological characteristics and flavour of FCM. [ABSTRACT FROM AUTHOR]

Poor ductility is the primary concern of magnesium matrix composites (MMCs) inflicted by non-deformable ceramic particle reinforcements. Metal particles which melt at elevated temperature can be used as reinforcement to improve the deformation characteristics. Ti-6Al-4V particles reinforced AZ31 MMCs were produced through friction stir processing (FSP) which was carried out in a traditional vertical milling machine. The microstructural features as well as the response to external tensile load were explored. A homogenous distribution of Ti-6Al-4V was achieved at every part of the stir zone. There was no chemical decomposition of Ti-6Al-4V. Further, Ti-6Al-4V did not react with Al and Zn present in AZ31 alloy to form new compounds. A continuous strong interface was obtained around Ti-6Al-4V particle with the matrix. Ti-6Al-4V particles underwent breakage during processing due to severe plastic strain. There was a remarkable refinement of grains in the composite caused by dynamic recrystallization in addition to the pinning of smaller size broken particles. Dense dislocations were observed in the matrix because of plastic deformation and the associated strain misfit. Ti-6Al-4V particles improved the tensile behavior and assisted to obtain appreciable deformation before fracture. Brittle mode of failure was avoided. [ABSTRACT FROM AUTHOR]

To prepare a self-lubricating ceramic tool with excellent mechanical properties and crack healing ability, the h-BN@Al 2 O 3 solid lubricant with a core-shell structure was prepared by the heterogeneous nucleation method, and was added into Al 2 O 3 /TiC ceramic matrix together with TiB 2. Examination of the micro-morphology and phase composition of h-BN@Al 2 O 3 found that the surface of the solid lubricant h-BN was coated with Al(OH) 3 at first, and after calcination at 1200 °C, a dense and uniform Al 2 O 3 shell was formed. At the same time, the effects of the h-BN@Al 2 O 3 addition on the ceramic tool material were studied. The mechanical properties of the ceramic tool material with h-BN@Al 2 O 3 were improved relative to than those with h-BN. The optimal content of h-BN@Al 2 O 3 solid lubricant was 5 vol%. In the friction and wear test, h-BN in h-BN@Al 2 O 3 particles can be stripped to form a solid lubricating film on the material surface, which plays a good role in reducing wear and resisting wear. The crack healing ability of the self-lubricating ceramic tool material was studied by prefabricating cracks with a length of 400 μm on the surface. After a heat treatment at 700 °C for 60 min, the surface cracks of the ceramic tool material were completely healed, and the flexural strength was restored to 90% of that of the smooth samples. The oxidation of TiB 2 and h-BN in ceramic tool materials is the main reason for crack healing. [ABSTRACT FROM AUTHOR]

The development of hybrid solder for chip packing is a major 3D packaging research topic. The incorporation of with low melting points into solder materials has been used in low-temperature packaging. Hybrid solder struggles to enhance low-temperature solder efficiency and mechanical properties. This work examined the effects of Co elements on microstructure and intermetallic compound (IMC) morphology of SAC305-SnBi-Co hybrid solder generated by reflow welding on electroless nickel immersion gold (ENIG) substrate at various temperatures. Moreover, mechanical characteristics and failure behavior of joints were extensively explored. The results show that the addition of 0.05% Co reduced the melting range of the solder and improved the wettability of SnBi solder. According to transmission electron microscopes (TEM) and electron diffraction spots (EDS), the crystal structure of the grains is (Cu, Co) 6 Sn 5 basic-centered monoclinic crystal. Fourier analysis of high-resolution images yields deformed lattice fringes, indicating that Co atoms fill Cu 6 Sn 5 's lattice gap in IMC. The shear strength of SAC305/SnBi hybrid solder joints with Co rises and then decreases with temperature. The highest shear strength of solder joints with 0.05% Co (40 nm) is 73.2 MPa at 220 °C, whereas joints with 0.1%Co are 67.5 MPa. Combined with the fracture morphology, the proportion of IMC fracture mode decreased after adding Co element. • Hybrid solder was combined with Co nanoparticles (0.05%, 0.1%) and reflow welded on the ENIG to generate solder joints. Co elements' effects on microstructure and IMC morphology at various temperatures were examined, which were calculated using thermodynamics. • TEM was used to examine Co element existence and study IMC development. Using material analysis software, the energy change before and after the IMC element change was simulated, and the thermodynamics of Co element on IMC development was examined. • Mechanical characteristics of SAC305/SnBi hybrid solder joints containing Co nanoparticles were examined at various temperatures (170 °C–230 °C), and fracture modes, shear strength, and fracture shape were analyzed to understand solder joint failure. [ABSTRACT FROM AUTHOR]

• Recycling waste tires can protect environment and achieve sustainable development. • The properties of CRC are systemically discussed and compared with those of NAC. • The microstructure of CRC is summarized. The utilisation and reuse of waste tire rubber in concrete can reduce the consumption of raw materials, which leads to economic efficiency and sustainable development of the construction industry. In this review, we conclude the major achievement of crumb rubber concrete (CRC) in nearly 5 years, discuss and analyse its fresh concrete properties, mechanical properties, durability and other properties. Results show that utilising the hydrophobic nature of rubber particles and appropriate admixture can increase slump and improve the workability of concrete. Concrete incorporating crumb rubber (CR) particles decreases the fresh density, and it decreases linearly with the increase in the CR content. The mechanical properties of concrete generally decrease as the CR content incorporated increases. However, the compressive and flexural strength of CRC, which is slightly above that of natural aggregate concrete (NAC), is limited to fine CR size that replaces sand and optimum CR replacement level (CR content from 0% to 10% increases the compressive strength by 2%, and the flexural strength is increased by 7%–21% in mixes with 10%–20% CR). CRC has higher water absorption and permeability than NAC. Nevertheless, small amounts of rubber replacement level (2.5%–7.5% CR) and mixing different rubber particle sizes can reduce the water absorption of concrete. CRC exhibits high freeze–thaw resistance, electrical resistance, abrasion resistance and resistance to sulfuric and sulfate attack when incorporating proper CR content at concrete mixes. The depth of chloride-ion penetration of CRC decreases with low CR content (up to 27.3% of reduction for CR content of 5%) but increases when the CR content exceeds 20%. A clear advantage of CRC is favourable thermal and acoustic insulation. The mechanical properties and durability of CRC can be improved by adding treated CR particles, fibres and supplementary cementing materials. Further research is needed to improve the weak bonding in the interfacial transition zone between CR aggregates and cement paste, thereby increasing the mechanical properties and durability of CRC. Discussions in this paper can provide new knowledge and information on the applications of green and sustainable CRC. [ABSTRACT FROM AUTHOR]

Glass ceramics were synthetized using Cr 2 O 3 and CaF 2 as additives, and their structure, crystal growth behavior, and physicochemical properties were investigated. The results showed that an excessive amount of Cr 2 O 3 leads to the formation of a spinel structure in the glass matrix and an increase in the number of Q3Si units. The addition of CaF 2 promoted the decomposition of Q2Si into Q1Si and Q3Si. Compared with the sample with Cr 2 O 3 alone, the addition of CaF 2 helped reduce the glass transition and crystallization temperatures, forming sharper crystallization peaks. Although CaF 2 increased the activation energy of crystallization, it increased the degree of crystallinity and Avrami parameter (2.019). In terms of the microstructure, the sample added with CaF 2 formed a snowflake-like structure with a spinel core. An excessive amount of spinel reduced the strength of the samples. The samples (1.5Cr 2 O 3 -3.5CaF 2) exhibited a maximum flexural strength of 149.85 MPa and a good chemical resistance. [ABSTRACT FROM AUTHOR]

Carbon nanotubes reinforced aluminum matrix nanocomposites were fabricated by friction stir processing. Raman spectroscopy, scanning electron microscope, transmission electron microscopy and tensile tests were used to characterize microstructures and mechanical properties of the nanocomposites. Effects of energy input during friction stir processing on microstructures and mechanical properties of the nanocomposites were investigated. It was found that the grain of aluminum matrix in the nanocomposites was coarsened slightly with the increase of energy input. Microstructure analysis showed that carbon nanotubes were successfully incorporated into aluminum matrix by friction stir processing and well bonded interfaces between the carbon nanotubes and aluminum matrix were formed. However, the carbon nanotubes dispersion and mechanical properties of the nanocomposites fabricated with different energy inputs were quite different, in which better carbon nanotubes dispersion and higher tensile strength could be obtained by applying higher energy input during the fabrication process. By applying the highest energy input, the tensile strength of the nanocomposite was 53.8% higher than that of the unreinforced aluminum. Meanwhile, the elongation of the nanocomposite was 31.2%, which showed an excellent ductility. The strengthening mechanisms were the synergy of Orowan looping, load transfer and grain refining. The present findings may provide the guidance on the optimization of the processing parameters during friction stir processing for fabricating the high performance aluminum/CNTs nanocomposites. • Effects of energy input during FSP on CNTs/aluminum composites were investigated. • CNTs dispersion was improved with the increase of energy input. • The tensile strength of composites was enhanced with the increase of energy input. • Three possible strengthening mechanisms were discussed. [ABSTRACT FROM AUTHOR]

Cr 2 O 3 is often used as a glass additive to prepare glass ceramics. Chromium element exists mainly in two parts in the glass ceramics: chromium-containing spinel and soluble chromium in glass matrix. Herein, effect of soluble chromium on the CaO-MgO-SiO 2 -(Na 2 O) glass system is researched. Glass and glass ceramics were characterized by Raman spectrum, X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry. It is found that the addition of Cr 2 O 3 increased the Q2si structure unit in glass networks, especially in glass systems with high MgO content. The crystallization temperatures of the systems were increased with the addition of Cr 2 O 3. Soluble chromium reduced the crystallization activation energy of the glass system slightly, but did not alter its crystallization behavior (surface crystallization). With the increase of MgO content, the mineral phases of the glass ceramics gradually changed from wollastonite to diopside. Cr 2 O 3 reduced the lattice parameters of the mineral phases. The addition of Cr 2 O 3 has a significant effect on grain refinement and structural compactness of the glass ceramics system with high MgO content. [ABSTRACT FROM AUTHOR]

Highlights • A four-stage cycle of surface, mortar, ITZ and natural aggregate crushing was proposed for C-RCA. • Carbonation treatment exerted a greater effect on the stress at the initial crack than the maximum stress. • A smaller C-RCA particle size resulted in a higher crushing stress. • Carbonation treatment of RCA improved both the attached mortar and the ITZ. Abstract This work investigated the effects of the carbonation treatment on the crushing characteristics of recycled concrete aggregates (RCAs). Single-particle crushing test was conducted on more than 300 RCAs and carbonated RCAs (C-RCAs) with particle sizes of 20–30, 30–40, and >40 mm. The results indicated that the single-particle crushing test of the C-RCA had a four-stage crushing cycle which was on repeat because of the presence of natural aggregates. Carbonation treatment increased the crushing stresses and reduced the water absorption (WA) of the RCA. The stress at the initial crack and maximum stress of the C-RCA were higher than those of the RCA, and carbonation treatment exerted a greater influence on the former than on the latter. A weak linear relationship was detected between the two stresses and the physical properties (WA and attached mortar content) of the C-RCAs and the RCAs. Moreover, CO 2 could be captured more effectively with smaller RCAs. Compared with RCAs with different particle sizes, the C-RCA with particle size of 20–30 mm showed significantly improved stress at the initial crack and maximum stress. By contrast, the >40 mm C-RCA had little difference from the RCA. The microhardness and scanning electron microscopy analyses of the C-RCA mesostructure agreed with the results of the WA, stress at initial crack and maximum stress of C-RCA, confirming that the carbonation treatment of RCA enhanced not only the original interfacial transition zone but also the attached mortar in the RCA, although the former was more significantly enhanced than the latter. [ABSTRACT FROM AUTHOR]

Microwave Hybrid Heating (MHH) is a novel approach for material joining that is gaining attention due to its ability to achieve selective and uniform heating compared to conventional methods. In this experimental study, we prepared and characterized Sn-3.0Ag-0.5Cu nanoparticles. We investigated the interface morphology, phase composition, and mechanical properties of joints fabricated using the nano-Sn-3.0Ag-0.5Cu soldering paste and MHH technique with varying exposure times. Additionally, a reliability assessment was performed on these joints. This research investigated the impact of varying exposure times, ranging from 165 s to 420 s, on both the microstructure and strength of the joints. The joints were successfully produced under conditions of 900 W and 195 s using the MHH technique. Analysis was conducted to assess the joint morphology and mechanical properties of the after undergoing thermal shock tests, aiming to assess the reliability of joints manufactured through the MHH technique. The experimental findings revealed that the shear strength attained its peak value of 44.8 MPa when subjected to a microwave power of 900 W and an exposure time of 195 s. Moreover, the shear strength of MHH joints exhibited a 24.4% decrease after 1200 thermal shocks. Fracture analysis consistently indicated ductile fracture during thermal shocks, with no alteration in fracture mode observed. • A novel synthesis method of Sn-3.0Ag-0.5Cu nano-solder paste was fabricated and optimized, which had better mechanical properties in joining field. • Microwave Hybrid Heating (MHH) was presented as an emerging material joining technique known for its uniform heating compared to conventional methods. • Analysis was performed to evaluate the joint morphology and mechanical properties of the after undergoing thermal shock tests, aiming to assess the reliability of joints manufactured through the MHH technique. [ABSTRACT FROM AUTHOR]

Diopside is the main crystalline phase in silicate materials such as ceramics and glass-ceramics. Herein, the effect of Cr 2 O 3 on the microstructure and crystallization behavior of synthetic diopside, as well as the solubility of Cr 2 O 3 in diopside is discussed. Samples were prepared by the melting method and characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, and confocal laser scanning microscopy. Results show that the maximum achievable solubility of Cr 2 O 3 in diopside is between 1% and 3% by weight, and that the magnesiachrome spinel formed by Cr 2 O 3 can act as a nucleating agent for the diopside phase. Glass ceramics was prepared by synthesis slag which simulates the chromium-containing waste. The activation energy of crystallization is 274 KJ/mol and Avrami parameter is 3.23. The leaching behavior of glass ceramics was studied. Additionally, the effect of Cr 2 O 3 on the mechanisms of phase change were discussed. The study provides a theoretical basis for the preparation of chromium containing waste-based silicate materials with diopside as the main crystalline phase. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the hydrogen embrittlement (HE) susceptibility and influence mechanism of X80 weld joints. Slow strain rate testing (SSRT) under in situ H-charging, combined with microstructure and fracture analysis, was performed on the base metal (BM), weld metal (WM), thermally simulated fine-grained heat-affected zone (FGHAZ) and coarse-grained heat-affected zone (CGHAZ). Results showed that the WM and simulated HAZ had a greater degree of high local strain distribution than the BM; compared to the CGHAZ, the FGHAZ had lower microhardness and more uniformly distributed stress. SSRT results showed that the weld joint was highly sensitive to HE; the HE index decreased in the following sequence: FGHAZ, WM, CGHAZ and BM. The effect of the microstructure on HE was mainly reflected in microstructure, local stress distribution and microhardness. [ABSTRACT FROM AUTHOR]

A rapid and efficient method is particularly necessary in the timely disposal of seriously radioactive contaminated soil. In this paper, a series of simulated radioactive soil waste containing different contents of neodymium oxide (3–25 wt.%) has been successfully vitrified by microwave sintering at 1300 °C for 30 min. The microstructures, morphology, element distribution, density and chemical durability of as obtained vitrified forms have been analyzed. The results show that the amorphous structure, homogeneous element distribution, and regular density improvement are well kept, except slight cracks emerge on the magnified surface for the 25 wt.% Nd 2 O 3 -containing sample. Moreover, all the vitrified forms exhibit excellent chemical durability, and the leaching rates of Nd are kept as ∼10 −4 –10 −6 g/(m 2 day) within 42 days. This demonstrates a potential application of microwave sintering in radioactive contaminated soil disposal. [ABSTRACT FROM AUTHOR]

Ti-Cu-N coatings with three different Cu contents on Ti-6Al-4V alloy (TC4) were obtained via laser cladding together with laser nitriding (LC/LN) technology. Phase constituents, microstructure, microhardness, and wear resistance of the coatings were investigated. The evolution of the coefficients of friction for the three coatings was measured under dry sliding conditions as a function of the revolutions until the coating failure. The results show that the coatings are mainly composed of TiN, CuTi and some TiO phases dispersed in the matrix. A good metallurgical bonding between the coating and substrate has been successfully obtained. The prepared Ti-Cu-N composite coatings almost doubly enhance the microhardness of the TC4 alloy and reduce the friction down to 1/4-1/2 of the TC4 alloy, and thus significantly improve the wear resistance. The coefficient of friction depends on the Cu content in the coating. [ABSTRACT FROM AUTHOR]

Strontium titanite (SrTiO 3 ), which is an experimentally-friendly thermoelectric material, could be a promising candidate for thermoelectric power generation applications. The theorectical study indicates the co-doping of La and Nb could enhance the thermoelectric performance, however, the thermoelectric figure of merits ( ZT s) of SrTiO 3 are still low because the co-doping process at nano-scale is experimentally difficult to control. Here we report a high performance SrTiO 3 with La-Nb co-doping, which are prepared by a combination of hydrothermal method and high-efficiency sintering. Nano-scale co-doping is successfully modulated by hydrothermal method, and nano-inclusions precipitate during sintering process, to form complex microstructures. In this case, the electrical and thermal transport properties are optimized simultaneously by doping concentration and dopants type, resulting in a record-high ZT >0.6 at 1000−1100 K in the 10 mol% La and 10 mol% Nb doped SrTiO 3 bulk materials. The nano-scale modulation doping and microstructure controlling approach validated in the present study should be also applicable for other thermoelectric materials. [ABSTRACT FROM AUTHOR]

The optical quality and microstructure of the Tb3Al2.5 Ga2.5O12 transparent ceramic were investigated and compared with those of terbium gallium garnet (Tb3Ga5O12 TGG) and terbium aluminum garnet (Tb3Al5O12 TAG). The transmission of the Tb3Al2.5 Ga2.5O12 ceramic was as high as 80% in the visible and near-infrared ( IR) regions, which was close to the theoretical value. The Verdet constant of the Tb3Al2.5 Ga2.5O12 ceramic measured at 632.8 nm and room temperature was −150.6 rad/Tm, which was 12% larger than that of the TGG single crystal and 13% smaller than that of the TAG single crystal, and the Tb3Al2.5 Ga2.5O12 ceramic showed the highest transparency among these three samples. [ABSTRACT FROM AUTHOR]

Red mudstone landslides are widespread in southwest of China. The development and distribution of deep-seated landsides with slow inclination are closely related to the special soft rock properties of the red mudstone layers. Most previous studies focused on the failure mechanisms of rain-induced shallow landslides. Studies on deep-seated landslides in red layer zones are still limited. In order to ascertain the basic failure mechanisms of red layer landslides with a gentle inclination, a fatal landslide named as Shibangou landslide, which occurred in Sichuan, China, was investigated. This paper aims to (1) conduct laboratory tests on the reduction in shear strength of a red layer to identify the water–rock coupling effect; (2) investigate variations in the microscopic structure of the soft rock found within a red layer after rainfall infiltration; (3) discuss the failure mechanisms of red layer landslides with slow inclination. Results from shear test of mudstone from the Shibangou landslide revealed that there is a tendency that behavior of soft rock can be transferred to soil in different days of immersion. The delineation threshold of shear strength of the red layer is determined as 6 days of immersion. Microstructures of clay minerals become loose and porous due to the contacts between the particles transferred from the face–edges, face–face associations into edge–edge, and face–edge associations. Therefore, the intramolecular and cemented expansions of illite are the basic mechanisms which lead to structural damage, structural decay, and strength attenuation of soft rock in red layer under the condition of rainwater infiltration. [ABSTRACT FROM AUTHOR]