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This work models the microstructural evolution as a function of position in laser-wire deposited Ti–6Al–4V parts using a classical multi-component JMAK nucleation and growth model with additive isothermal time-steps. Model predictions are compared to experimental observations. The model can be used to interpret nucleation and growth kinetics of various characteristic features of the microstructure that are inaccessible by experiments. It explains the presence of "layer bands" at specific locations unrelated to the weld bead structure. The last re-heating (of multiple thermal cycles) of a solidified layer, and where it peaks, plays a key role in increasing the nucleation density at specific locations, resulting in full α -colony microstructures constituting the "layer bands," while the rest of the build is predominantly basketweave. Additionally, changes in the basketweave α -lath thickness as a function of the distance from the substrate are studied and compared with an Arrhenius-type function, with results highlighting a more complex relationship than an Arrhenius-type function would suggest. [ABSTRACT FROM AUTHOR]

This study investigates the influence of super-fast heating rate and holding time on the microstructure and mechanical properties of dual-phase (DP) Fe-0.16C-1.4Mn sheet steel. Super-fast heating and cooling rates were achieved via induction heating and gas quenching. The results were also compared with those for a conventional low-speed heat treatment. The microstructures were characterized in detail using X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, and electron probe microanalysis. The results showed that the layered structure of the DP Fe-0.16C-1.4Mn steel after super-fast heating was mainly composed of recrystallized ferrite, martensite clusters, and a small amount of residual austenite. Compared with the conventional method, super-fast heating significantly refined the grains and improved yield and tensile strength, but it slightly reduced the elongation. The fraction of martensite, which depends on the nucleation and growth behavior of austenite, was significantly affected by the heating rate and holding time. The DP structure of Fe-0.16C-1.4Mn steel had an atypical layered heterogeneous structure, with an uneven plastic strain between the two phases occurring during the deformation process, which is something that can improve fracture elongation. [ABSTRACT FROM AUTHOR]

In this paper, the nucleation and growth of austenite are controlled through a two-step annealing process to achieve multi-scale distribution and content increase of retained austenite in low manganese series medium-Mn steel. Combining SEM, EBSD, AES, and other experimental equipment, the evolution rules of the microstructure, properties, and element distribution behavior of the test steel during the annealing process are studied. Compared with one-step annealing, the two-step annealing significantly broadens the size distribution range of retained austenite. In the first step, after annealing at a higher intercritical temperature (760 °C), the ferrite and the M/A island are obtained, completing the initial partition of Mn and the refinement of microstructures. During the second step of annealing (720 °C), the primary Mn-rich martensite region provides higher nucleation driving force and finer dispersed nucleation sites, promoting the nucleation and growth of reverse transformation austenite. At the same time, the metastable-retained austenite formed after the first step of annealing continues to grow through interface movement. Furthermore, a high proportion (23.4%) of retained austenite with multi-scale distribution is formed in the final microstructure, and the product of strength and elongation increased from 21.8 GPa·% by the one-step annealing process to 30.1 GPa·%. [ABSTRACT FROM AUTHOR]

The computer-aided cooling curve analysis (CA-CCA) was employed to investigate the solidification behavior of Al-Ce-Mg-xCe (x = 0, 0.5, 1.0, 1.5, and 3.0 mass %) alloys. Field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques were used, along with the liquidus projection of ternary Al-Cu-Mg and Al-Cu-Ce phase diagrams, to evaluate the microstructure and predict the sequence of main reactions involved in the solidification of alloys. According to the results, Al2CuMg, Al2Cu, Al15(CuFeMn)3Si2, and Mg2Si were found to be the main compounds present in the microstructure of Al 2024 alloy. The addition of Ce up to 1.5 mass % resulted in the formation of AlCeCuSi, Al8CeCu4, and Al24Cu8Ce3Mn compounds in the microstructure. Further addition of Ce up to 3.0 mass % promoted the formation of a new Ce-rich phase (Al4Ce) in the microstructure. The formation temperature (range) and reactions during which the Ce-rich compounds are formed were also suggested. The formation of Al4Ce compound in the microstructure of 3 mass % Ce-containing samples suppressed the nucleation and growth temperatures of the Al2Cu eutectic, prolonged the solidification time, significantly reduced the solidification end temperature, and increased the alloy solidification range. [ABSTRACT FROM AUTHOR]

Dislocation tangle and coarse precipitate segregation cause incalculable damage to the strength and ductility of high-strength Al-Zn-Mg-Cu aluminum alloys. These drawbacks are inevitable for the alloys undergoing deformation and artificial aging. In this work, electroshock treatment (EST) was successfully introduced between deformation and artificial aging of the alloys to improve their strength and ductility. The uniaxial tensile test results show that the elongation of the samples with EST could increase by 28.8%, and the ultimate strength simultaneously increases by 20 MPa relative to that without EST samples. Through microstructure characterization, it was found that EST eliminates dislocation tangle resulting from pre-stretching in the material. Furthermore, the distribution of coarse precipitates in EST samples is more uniform, and the size of precipitates is smaller in comparison with non-EST samples. The dislocation evolution induced by EST could be attributed to the non-equilibrium scattering of electron-dislocation, and a kinetic model for nucleation and growth of precipitates has been proposed to reveal the mechanism of precipitate evolution. [ABSTRACT FROM AUTHOR]

The phase transformations in an as-cast Fe-30Mn-8.8Al-0.3Si-0.15C steel were analyzed experimentally and numerically with a Calphad-based method during heat treatment. The nonequilibrium phases were determined using the Thermo-Calc Scheil module and the equilibrium phases with Themo-Calc based on the steel chemical composition. The precipitated phases were analyzed with TC-PRISMA using the chemical composition, nucleation site, and temperature among other factors. An ingot of this chemical composition was vacuum-melted using pure elements under an Ar gas atmosphere. As-cast steel specimens were annealed and solution-treated, quenched, and then aged at different temperatures. Heat-treated specimens were analyzed by different techniques. The results indicated that the microconstituents are the α and γ phases for the as-cast, homogenized, and quenched conditions. The main difference among these conditions is the distribution and size of the γ phase, which produced a change in hardness from 209 to 259 VHN. In contrast, the aging treatment at 750 °C caused a decrease in hardness from 492 to 306 VHN, which is attributable to the increase in volume fraction of the γ phase. On the other hand, the aging treatment at 550 °C promoted precipitation hardening from 259 to 649 VHN because of the κ precipitate formation. The calculated results for the different heat treatments with the Calphad-based method agreed well with the experimental ones. In addition, the intragranular precipitation of the κ phase could be simulated using the nucleation and growth and coarsening mechanisms based on a Calphad method. [ABSTRACT FROM AUTHOR]

Mg-Al layered double hydroxide (LDH) films were fabricated on LA103Z Mg-Li alloy substrates by an in situ hydrothermal method that involved various Al(NO3)3 concentrations. The microstructure, composition, and morphology of the Mg-Al LDH films were investigated via x-ray diffraction, energy-dispersive x-ray spectroscopy, and scanning electron microscopy, respectively. The corrosion behaviors of the LDH films were characterized using electrochemical measurements and a hydrogen evolution rate test. The results revealed that the concentration of Al(NO3)3 was a key factor in the formation of the LDH that affected the nucleation and growth process of the LDH. An appropriate increase in the Al(NO3)3 concentration promoted the growth of the LDH and thus improved the anticorrosion properties of the film. At an Al(NO3)3 concentration of 0.05 M, the LDH film was uniform and dense with optimal thickness. The results of electrochemical and corrosion tests showed that the anticorrosion properties of the bare substrate were markedly improved. The enhancement effect of the film prepared using 0.05 M Al(NO3)3 was the best. Its hydrogen evolution rate was 0.01082 mL cm−2 h−1, and its corrosion current density was 7.369 × 10−5 A/cm2. [ABSTRACT FROM AUTHOR]

Typically, in the manufacturing of GH4169 superalloy forgings, the multi-process hot forming that consists of pre-deformation, heat treatment and final deformation is required. This study focuses on the microstructural evolution throughout hot working processes. Considering that δ phase can promote nucleation and limit the growth of grains, a process route was designed, including pre-deformation, aging treatment (AT) to precipitate sufficient δ phases, high temperature holding (HTH) to uniformly heat the forging, and final deformation. The results show that the uneven strain distribution after pre-deformation has a significant impact on the subsequent refinement of the grain microstructure due to the complex coupling relationship between the evolution of the δ phase and recrystallization behavior. After the final deformation, the fine-grain microstructure with short rod-like δ phases as boundaries is easy to form in the region with a large strain of the pre-forging. However, necklace-like mixed grain microstructure is formed in the region with a small strain of the pre-forging. In addition, when the microstructure before final deformation consists of mixed grains, dynamic recrystallization (DRX) nucleation behavior preferentially depends on kernel average misorientation (KAM) values. A large KAM can promote the formation of DRX nuclei. When the KAM values are close, a smaller average grain size of mixed-grain microstructure is more conductive to promote the DRX nucleation. Finally, the interaction mechanisms between δ phase and DRX nucleation are revealed. [ABSTRACT FROM AUTHOR]

Calcium oxalate kidney stones, the most prevalent type of kidney stones, undergo a multi-step process of crystal nucleation, growth, aggregation, and secondary transition. The secondary transition has been rather overlooked, and thus, the effects on the disease and the underlying mechanism remain unclear. Here, we show, by periodic micro-CT images of human kidney stones in an ex vivo incubation experiment, that the growth of porous aggregates of calcium oxalate dihydrate (COD) crystals triggers the hardening of the kidney stones that causes difficulty in lithotripsy of kidney stone disease in the secondary transition. This hardening was caused by the internal nucleation and growth of precise calcium oxalate monohydrate (COM) crystals from isolated urine in which the calcium oxalate concentrations decreased by the growth of COD in closed grain boundaries of COD aggregate kidney stones. Reducing the calcium oxalate concentrations in urine is regarded as a typical approach for avoiding the recurrence. However, our results revealed that the decrease of the concentrations in closed microenvironments conversely promotes the transition of the COD aggregates into hard COM aggregates. We anticipate that the suppression of the secondary transition has the potential to manage the deterioration of kidney stone disease. [ABSTRACT FROM AUTHOR]

Additive manufacturing is increasingly being employed to produce components of complex geometries in structural alloys because of the expected energy savings associated with the near-net-shape capability and the ability to build in novel internal features that are not possible with many conventional manufacturing approaches. However, because of the extreme thermal conditions encountered, the non-equilibrium microstructures produced during powder bed-based additive manufacturing processes must be subjected to custom post-heat treatment processes to recover the target mechanical properties. Phase-field models and simulation techniques have matured to a state where the microstructure evolution paths, and the morphologies of the resulting precipitate phases can be predicted reasonably accurately, considering alloy-specific thermodynamic and kinetic aspects of the nucleation and growth processes. However, phase-field simulations are computationally intensive, which precludes the ability to apply the simulations directly to the length scale of the entire component. Therefore, it is highly desirable to develop low-computational-cost surrogate models that effectively capture the physics at the microstructural length scale, while facilitating the design of optimized processing conditions resulting in location-specific targeted microstructures at the component scale. The work presented here demonstrates the application of the materials knowledge system framework to develop a surrogate model that effectively captures the microstructural path during annealing of a Ni–Mo–Nb alloy containing different Mo and Nb compositions known to segregate during solidification under additive manufacturing conditions. Specifically, the surrogate model built in this work is based on a Gaussian process autoregressive model informed by statistical representation of simulated microstructures using two-point correlations and dimensionality reduction through principal component analysis. This surrogate model is shown to capture the bifurcation of the microstructural path during precipitation, which yields a microstructure dominated by the γ ′ ′ phase at high Nb concentrations and the δ phase at low Nb concentrations. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) aerogels with spider network structure, bead-like connected microsphere structure, and cluster petal structure were fabricated by precisely controlling the phase separation behavior (nucleation growth and spinodal separation) of the ternary solution system. The PLA aerogel with ideal spider network structure achieved an extremely high porosity of 96% and a high specific surface area of 114 m2/g, which rendered it with excellent triboelectric energy generation performance. [Display omitted] Aerogels with 3D porous structures have been attracting increasing attention among functional materials due to their advantages of being lightweight and high specific surface area. Precise control of the porous structure of aerogel is essential to improve its performance. In this work, polylactic acid (PLA) aerogels with distinctly different microstructures were fabricated by precisely controlling the phase separation behavior of the ternary solution system. Rheological and theoretical analyses have revealed that the interactions between polymer molecules, solvents and non-solvents play a crucial role in determining the nucleation and growth of poor olymer and rich polymer phases. By adjusting the non-solvent type and the solution composition, aerogels with spider network structure, bead-like connected microsphere structure, and cluster petal structure were obtained. Ideal spinodal phase separation conditions were obtained to produce aerogels with a homogeneous fiber network structure. The optimum PLA aerogel achieved an extremely porosity of 96 % and a high specific surface area of 114 m2/g, which rendered it with excellent triboelectric generation performance. Thus, this work provides fundamental insights into the precise regulation of the phase separation behavior and the structure of the aerogel, which can help boost the performance and expand the applications of PLA aerogels. [ABSTRACT FROM AUTHOR]

The static recrystallization behaviour and microstructure evolution of cold rolled (CR) Ti-B20 alloy with high strength during annealing were investigated using electron back-scattered diffraction and x-ray diffraction methods. Results suggest that the deformation bands and grain boundaries in the CR Ti-B20 alloy became a preferred nucleation position of recrystallized grains, which led to the formation of an uneven microstructure at the initial stage of annealing. After a given annealing time, the nucleation and growth rate of recrystallized grains accelerated with increasing annealing temperature. The relationship among the volume fraction of recrystallized grains, annealing temperature and annealing time can be described by the Johnson–Mehl–Avrami–Kolmogorov equations X 800 = 1 - exp (- 0.00011 ∗ t 1.64 and X 820 = 1 - exp (- 0.00009 ∗ t 1.98) . For the CR sheet specimens, a typical cold texture was formed, such as γ-fiber components of {111} < 110 > and {111} < 112 > textures. When complete recrystallization occurs for the CR sheet, the texture component primarily consists of {112} < 021 > for the CR sheet annealed at 800 and 820 °C. [ABSTRACT FROM AUTHOR]

In this study, X80 pipeline steel is prepared with different Nb contents through the thermo-mechanically controlled rolling process. The effects of using two different Nb contents on the impact toughness and microstructure of the pipeline steel are examined using various experimental techniques. The results show that with the increase in Nb content, the transformation temperature Ar3 decreases, and the nucleation and growth of bainitic ferrite with lath features (LB) are promoted, while those of granular bainite (GB) are inhibited. In addition, the stability of the austenite phase increases with the increase in Nb content. Therefore, the volume fractions of LB and martensite–austenite (M/A) constituents increase, while the proportion of high-angle grain boundaries (HAGBs) decreases. The impact energy of pipeline steel at −45 °C is closely related to the Nb content. Specifically, the impact energy decreases from 217 J at 0.05 wt.% Nb to 88 J at 0.08 wt.% Nb. The cracks are preferentially formed near the M/A constituents, and the HAGBs significantly inhibit the crack propagation. The steel with 0.05 wt.% Nb has a lower content of M/A constituents and a higher proportion of HAGBs than the one with 0.08 wt.% Nb. In addition, as the Nb content increases, the crack initiation energy and the crack propagation energy decrease. Thus, the 0.05 wt.% Nb steel has a higher low-temperature impact energy. [ABSTRACT FROM AUTHOR]

In this study, precursor decomposition as well as nucleation and growth processes during the preparation of In 2 O 3 powders via chemical precipitation were investigated. This is to provide guidance for the preparation of high-quality In-based oxide target powders. In-situ phase and microstructure evolution during thermal decomposition of precursors were analyzed. In addition, decomposition behavior of precursors at different heating rates was explored. Results show that amorphous In(OH) 3 precursor powder gradually decomposes and transforms into crystalline In 2 O 3 powder during heating process. Its degree of crystallinity increases with the increase in temperature. Fine and homogeneous In 2 O 3 powder with average grain size of 54.46 nm was obtained by holding the powder at 770 °C for 3 h. The decomposition of precursors at any given heating rate can be divided into two stages: (i) dehydration and (ii) nucleation and crystallization. However, higher heating rate clearly results in temperature hysteresis effect, the occurrence of decomposition reaction at higher temperature, and an increase in the maximum reaction rate of decomposition reaction. Moreover, activation energy of thermal decomposition was obtained using model-free transformation method. Decomposition reaction model of In(OH) 3 precursor was established using model-fitting method. It was deduced that first-stage reaction mechanism is three-dimensional diffusion. Reaction rate in this stage is controlled by product layer diffusion. Furthermore, second-stage reaction mechanism is random nucleation and subsequent growth. Reaction rate in this stage is controlled by nucleation and growth rates. [ABSTRACT FROM AUTHOR]

The effects of rare earth (RE) on the microstructure and mechanical properties of a pearlitic steel wire rod are investigated under the dual‐low‐oxygen condition. The results show that the wire rods with different RE contents all have pearlite microstructure. As RE content increases from 0 to 310 ppm, the pearlite substructures such as interlamellar spacing, pearlite colony size, and ferrite grain size decrease remarkably, indicating that the nucleation and growth behavior of pearlite change. This is attributed to the combined effects of stimulating nucleation by a large number of micrometer‐scale RE‐containing inclusions and decreased carbon diffusion due to RE in solution. As a result, the changes in microstructure lead to simultaneous enhancement of strength, plasticity, impact toughness, and microhardness of pearlite wire rod, demonstrating that adding appropriate content of RE under the dual‐low‐oxygen condition is an effective alloying method to optimize the microstructure and mechanical properties of pearlitic steel wire rod. [ABSTRACT FROM AUTHOR]

The effects of starting microstructure and intercritical annealing temperature on the phase‐transformation kinetics and microstructural evolution of a prototype Fe–0.15C–5.56Mn–1.1Si–1.89Al medium‐Mn third‐generation advanced high‐strength steel are examined. The starting microstructures comprise 1) an as‐received cold‐rolled (CR) microstructure containing a significant fraction of ferrite and tempered martensite and 2) an austenitized and quenched martensite–ferrite (MF) microstructure. Based on the microstructural observations, two different scenarios for austenite formation during intercritical annealing are proposed. For the CR starting microstructure, austenite can nucleate at ferrite/cementite interfaces, and at ferrite grain boundaries. In the case of the MF starting microstructure, which contains thin films of interlath retained austenite (RA), austenite forms on the martensite lath boundaries or grows directly from the existing interlath RA. The studies are interpreted using the DICTRA module of Thermo‐Calc. At 665 °C, the austenite reversion kinetics of the MF samples are faster than the transformation kinetics in the CR structure. At higher temperatures where most of the cementite has dissolved, the austenite fraction in both starting microstructures is very similar. [ABSTRACT FROM AUTHOR]

This year marks the 70th anniversary of the discovery of glass-ceramics. On this occasion, a review paper presenting this material and its progress from discovery to the present day is given. This paper explains what glass-ceramics are and points out the growth of interest in such materials and their commercial success. The process of preparing glass-ceramics is described, while special attention is paid to the role of nucleating agents, and the process of nucleation and growth. Factors that decisively affect the properties of glass-ceramics, such as the crystalline phase, its proportion, the composition of the remaining glass phase, and the microstructure, are listed. Owing to the influence of the mentioned factors, it is possible to prepare different types of glass-ceramics with various crystal phases and morphologies, and consequently different properties suitable for various purposes. The most important systems and types of glass-ceramics are presented, their properties and uses are described and explained. The names of the most important brands of commercial glass-ceramics are also mentioned. In the conclusion, a view of the perspective of this material, glass-ceramic types, and areas of application in which the progress is most certain are provided. [ABSTRACT FROM AUTHOR]

This paper investigated the combined effect of chemical activators and nano-SiO2 on the hydration reaction and the microstructure of γ-C2S. The hydration reaction of γ-C2S slurry activated with chemical activators (NaHCO3, NaOH, K2CO3, and KOH at 1 mol/L) was enhanced by 1% nano-SiO2. The hydrate reaction rate was determined by isothermal calorimetry, and the hydrated samples were characterized by XRD, TGA/DTG, SEM-EDS, and 29Si MAS/NMR. The results revealed a substantial enhancement in the hydration activity of γ-C2S due to the presence of the alkaline activator. Furthermore, nano-SiO2 did not alter the composition of γ-C2S hydration products, instead providing nucleation sites for the growth of hydration products. Incorporating nano-SiO2 promoted the formation of C-(R)-S-H gel with a low calcium-to-silica ratio and increased its polymerization levels, resulting in more favorable structures. Among all the activators used in this study, potassium salts had a better activation effect than sodium salts. After 28 days of curing, the degree of hydration reaction in the KC+Si group was 48% and about 37% for the NHC+Si group. Whereas, the KH+Si and NH+Si groups only reached approximately 20% after the same hydration duration. [ABSTRACT FROM AUTHOR]

Introduction: Metallographic replication has become an effective method in the study of residual life, to the point where normative documents of wide international application have been developed, such as the ASTM E1351-01 standard. Although this standard contemplates the use of scanning electron microscopy, it does not yet consider the use of transmission electron microscopy, despite it being convenient and feasible from a practical point of view. Objective: To establish the microstructural condition of the material of a SA335 Grade P11 steel steam pipe with over 20 years of service at 480 °C, using metallographic replication. Materials and Methods: Direct extraction replication was applied, combined with TEM. Results and Discussion: The microstructure present in the steel was of the ferrite-perlite type. The ferrite exhibited regular and uniformly sized intergranular and intragranular precipitation (approximately between 50 and 100 nm). At the service temperature, the ferrite would have reached, with respect to M2C (88% Mo, 6% Fe, and 6% Cr), a composition close to equilibrium after a process of nucleation and growth of M2C. Conclusions: The SA335 Grade P11 steel, after more than 20 years in service at 480 °C, exhibited a ferrite-perlite microstructure with intergranular and intragranular precipitation in the ferrite. The occurrence of competitive growth phenomenon due to the time and service temperature was evidenced. Metallographic replication, using MET, constitute an effective method to evaluate the microestructura of steam pipes. [ABSTRACT FROM AUTHOR]

Cu–15Ni–8Sn alloy is the best choice to replace beryllium bronze alloy. This alloy has unparalleled application value in aerospace, ocean engineering, electronic information, equipment manufacturing, and other fields. However, the application of Cu–15Ni–8Sn alloy is challenged and limited because of a series of problems in its preparation and processing, such as easy segregation, difficult deformation, and discontinuous precipitation. It is an effective way to improve the comprehensive properties of Cu–15Ni–8Sn alloy using alloying design and process optimization to control the as-cast, deformed, and heat-treated microstructures. At present, it is a hot spot for scholars to study. In this paper, the grade generation, system evolution, and preparation technology development of Cu–15Ni–8Sn alloy are comprehensively reviewed. The phase transformation sequence of the Cu–15Ni–8Sn alloy is discussed. The influence of the type, amount, and existing form of alloying elements on the strength of Cu–15Ni–8Sn alloy and its mechanism are systematically summarized. Furthermore, the latest research progress on the effects of solid solution, cold deformation, and aging on the phase structure transformation and mechanical properties of Cu–15Ni–8Sn alloy is summarized. Finally, the future development trend of the Cu–15Ni–8Sn alloy is projected. The research results of this paper can provide a reference for the control of the microstructure and properties of high-performance Cu–15Ni–8Sn alloys used in key fields, as well as the optimization of the preparation process and alloy composition. [ABSTRACT FROM AUTHOR]

Herein, non‐quenched and tempered forging steels containing V and V–Nb are designed, and the mechanical properties and microstructure of two steels are compared and analyzed. The comprehensive mechanical properties of V–Nb containing steel are as follows: the yield strength is 525.1 MPa, the impact energy AkV is 62.1 J at ambient temperature, and the elongation is 26.1%. It is shown in the results that the addition of Nb element can refine the grain size (17.2 μm), increase the ferrite content (54.1%), and refine the lamellar spacing of pearlite (274 nm). The formation of V (C, N) particles on MnS inclusions can promote fine ferrite nucleation and growth, and Nb element can further promote ferrite nucleation by forming coarser (V, Nb) (C, N) particles. The difference of yield strength and hardness between the two steels is mainly caused by the difference of precipitation strengthening, the precipitation‐strengthening increment of V–Nb containing steel is 18.31 MPa higher than that of V containing steel, which is because the coarser‐size (V, Nb) (C, N) particles produce stronger precipitation‐strengthening effect. But the large‐sized MnS inclusions are beneficial to the increase of crack driving force and reduce the plasticity and toughness. [ABSTRACT FROM AUTHOR]

Coarse-grain heat-affected zone (CGHAZ) properties of steel deteriorate when it is welded using high heat input, which always restricts the promotion and use of high heat input welding steel. TiN particles significantly inhibit the growth of austenite and improve the microstructure and properties of high heat input welding steel. Effects of different Ti/N ratios on the CGHAZ microstructure and properties of high heat input welding steel were studied using welding thermal simulations and in situ observations. Results showed that a higher Ti/N ratio led to the abnormal growth of austenite grains and promoted the nucleation and growth of lath ferrite, which made the microstructure of the CGHAZ heterogeneous. In contrast, austenite grains were more uniform at a lower Ti/N ratio. Thus, the microstructure was refined, the brittle structure was reduced, and the properties of the CGHAZ were improved. In addition, when Ti/N = 5.85, the impact absorption energy of the CGHAZ obviously fluctuated. However, when Ti/N = 2.82, the impact absorption energy of the CGHAZ was higher and more stable. These results provided a new idea for the development of high heat input welding steel based on TiN theory. [ABSTRACT FROM AUTHOR]

The low‐dimensional (LD) perovskites are proven to be capable of blocking moisture erosion and thereby improving the photovoltaic device stability. In this review, the low‐dimensional (LD) perovskite materials are carefully summarized that are induced by A‐position organic substituents, starting from the crystal microstructure and electronic structure of LD (2D, 1D, and 0D) perovskite materials with regulating dimensions, combined with first principles calculation (DFT). By further studying the thermodynamics and dynamics of crystallization nucleation and growth of LD–3D perovskite thin films in the heterojunction region, LD–3D heterojunction perovskite thin films and solar cells with controllable dimensions can be in situ prepared. Various LD–3D perovskite structure photovoltaic devices are systematically summarized, which shows flexible regulation of the energy band structure and carrier transport characteristics, locks the water oxygen corrosion channel with close‐fitting conjugated structure, and improves the long‐term stability of the LD–3D perovskite solar cells. This review is expected to provide some guidance for the perovskite development and multipurpose use through in depth understanding of the structurally dimensional engineering in perovskite photovoltaics. [ABSTRACT FROM AUTHOR]

Microstructure is a significant factor that influences the mechanical properties of alloys. The effect of multiaxial forging (MAF) and subsequent aging treatment on the precipitated phases of Al-Zn-Mg-Cu alloy remains unclear. Therefore, an Al-Zn-Mg-Cu alloy was processed by means of solid solution and aging treatment, and MAF and aging treatment in this work, and the composition and distribution of precipitated phases were characterized in detail. The MAF results for dislocation multiplication and grain refinement were found. The high density of dislocation greatly accelerates the nucleation and growth of precipitated phases. Thus, the GP-zones almost transform into precipitated phases during subsequent aging. The MAF and aging alloy has more precipitated phases than the solid solution and aging treated alloy. The precipitates on the grain boundary are coarse and discontinuously distributed due to dislocation and grain boundary promoting the nucleation, growth and coarsening of the precipitates. The hardness, strength, ductility and microstructures of the alloy have been studied. Without compromising the ductility much, the MAF and aging alloy has higher hardness and strength, with values of 202 HV and 606 MPa, respectively, and an appreciable ductility of 16.2%. [ABSTRACT FROM AUTHOR]

Intermetallic compounds (IMCs), known for their hardness, play an important role in the precipitation strengthening of alloys. However, precipitation in excessive amounts or as large particles can result in embrittlement of the material. Thus, controlling the distribution of IMCs among the matrix is crucial for the design of strong and ductile alloys. In this research, a supersaturated Ti-Cu alloy formed by Laser Powder Bed Fusion (L-PBF) was heat-treated at different phase regions to produce lamellar, network, and dispersed distributions of Ti2Cu IMC precipitates. To comprehensively understand the formation mechanisms of each IMC distribution structure, in-situ microstructure observation was performed during the heat-treatments. The lamellar IMC structure obtained from heat treatment above the beta-transus temperature, was found to derive from the rejection of Cu atoms towards the boundaries of lamellar alpha grains formed during cooling. The network IMC structure obtained from heat-treatment in the α+β phase region involved the formation of a Cu-rich β-Ti layer between α-Ti grains during heating, and subsequent precipitation of Ti2Cu into an α-encapsulating network upon cooling. Finally, the dispersed structure of IMCs was observed to result from regular nucleation and growth of Ti2Cu during heat treatment in the α+IMC region. [ABSTRACT FROM AUTHOR]

The present work investigated the electrochemical properties of laser-based additively manufactured CoCrMo in simulated body fluid, at physiological temperature (37 ∘ C). The extremely rapid thermokinetics inherently associated with the laser-based additive manufacturing led to heterogeneous microstructural evolution with cellular dendritic solidification and selective elemental segregation in CoCrMo fabricated using five different laser parameters. Such heterogeneous microstructure and composition led to spatially non-uniform corrosion response in additively manufactured CoCrMo. Despite such unique heterogeneity, the potentiodynamic polarization and electrochemical impedance spectroscopic parameters of the additively manufactured samples varied marginally compared to those of a conventionally manufactured CoCrMo sample. The heat treatment in argon at 1150 ∘ C for 150 min followed by furnace cooling led to a spatially uniform corrosion pattern with enhanced equilibrium potential in additively fabricated CoCrMo. Such improved corrosion response of additively fabricated CoCrMo samples was attributed to the formation of coarser equiaxed grains with discontinuous precipitation of Cr and Mo rich compounds/carbides at the boundaries and the absence of high-energy ϵ -martensite phase. [ABSTRACT FROM AUTHOR]

The effects of mixing temperature, i.e., the temperatures of two precursor melts (pure Al and Al-12Si), on the temperature and solute fields of resultant mixture, the nucleation and growth, and the size and morphology of primary grains during controlled diffusion solidification (CDS) of Al-8Si alloy were investigated by using simulation and calculation. The results indicate that a lower mixing temperature is helpful for achieving more supercooled microscale Al-rich pockets in the mixture, and increasing the width and supercooling degree of supercooling zone in the Al-rich pockets, and thus, the nucleation rate. The nuclei grow up in nondendritic mode, resulting in spheroidal, at least, nondendritic grains. In a successful CDS, the superheat degrees of the two precursor melts should be limited within several degrees, and it is not necessary to extra stipulate the superheat degree of target alloy melt (Al-8Si) when the requirement about Gibbs energies of the three melts is matched. Subsequent observation on casting microstructures shows that the employed simulation and calculation processes are reasonable and the achieved results are reliable. [ABSTRACT FROM AUTHOR]

Coal gasification coarse slag (GFS) is a byproduct of coal gasification technology, which contains abundant amorphous aluminosilicate minerals. GFS has low carbon content, and its ground powder has potential pozzolanic activity, which can be used as a supplementary cementitious material (SCM) for cement. Herein, GFS-blended cement was studied in terms of ion dissolution characteristics, initial hydration kinetics, hydration reaction process, microstructure evolution process, and the development of the mechanical strength of their paste and mortar. Enhanced alkalinity and elevated temperature could increase the pozzolanic activity of GFS powder. The specific surface area of GFS powder and its content did not change the reaction mechanism of cement. The hydration process was divided into three stages: crystal nucleation and growth (NG), phase boundary reaction (I), and diffusion reaction (D). A higher specific surface area of the GFS powder could improve the chemical kinetic process of the cement system. The degree of reaction of GFS powder and blended cement had a positive correlation. A low GFS powder content (10%) with a high specific surface area (463 m2/kg) showed the best activation in cement as well as improving the late mechanical properties of cement. The results show GFS powder with low carbon content has the application value as SCM. [ABSTRACT FROM AUTHOR]

The particle size distribution and solidification of dispersed Cu-rich particles within the core region of stable core shell microstructures in drop tube processed metastable Cu-50 at. % Co alloy was studied with a view of understanding the evolution and growth of these microstructures. Microstructural evidence indicates that the formation of the core shell microstructures is highly influenced by nucleation and growth phenomenon. Coalescence propelled by collision is favoured in smaller droplets owing to their higher cooling rates and subsequent higher degree of undercooling to facilitate the liquid phase separation process. Weaker Marangoni motion impeded the further convergence of the Cu-rich particles within the core region. [ABSTRACT FROM AUTHOR]

To continue to meet the future materials' requirements for advanced power generation systems, enhancing the mechanical properties and long-term phase stability of Ni–Fe-based alloys is needed. In this study, alloying modifications were made to improve the phase stability and 0.2 pct yield strength of modified cast austenitic stainless steels used for high-temperature heat exchanger applications. The focus was to investigate the influence of Cr concentration and the ratio of Ni/Fe in the alloy system on the elevated temperature yield strength, ductility, and its matrix phase stability. Over the range of experimental alloy compositions investigated, the best balance of mechanical properties in tension at 750 °C was achieved through a modest reduction in Cr as this alloy possessed a yield strength of 630 MPa and 28 pct elongation. The σ phase volume fraction was also limited compared with other alloys. The modifications in Cr concentration and Ni/Fe ratio to the alloy system are independent with the γ′ precipitate solvus temperature and volume fraction formed during aging. However, decreasing Cr concentration from 21 at to 18 at.pct was observed to increase the yield strength and decrease the fraction of σ phase precipitation. Reductions in the Ni/Fe ratio led to a reduction of the tensile ductility as this tended to promote the formation of discontinuous precipitation along the grain boundary. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nonferrous Metals (Mining Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The microstructural evolution of a T800 2 × 2 twill weave carbon fiber/benzoxazine resin composite was quantified through the pyrolytic decomposition region of 250–800°C. In performing kinetic analysis, three stages of mass loss were identified and quantified through a non-isothermal kinetics model. The kinetics model parameters were determined at each state of the reaction, and the corresponding decomposition gases were analyzed to gain insight into pyrolytic reactions. The kinetics model was then used to design a heat treatment cycle that isolated each stage of the reaction so that the effects on the progression of the porous microstructure could be characterized. In the first stage of the reaction, the nucleation and growth of voids were dominant. In the second stage, the initiation of microcracks within the matrix was observed. The third stage saw the formation of an interconnected porous network in which cracks propagated throughout the composite and formed a continuous pathway from the surface to the centermost voids. To evaluate these microstructural features, X-ray computed tomography was utilized. In doing so, the various damage phenomena including void size, the degree of open and closed porosity, and the crack density were quantified. [ABSTRACT FROM AUTHOR]

The aluminum alloys corresponding to the 6000 series are mainly manufactured by mechanical forming processes. Their properties are enhanced by the homogeneous distribution of intermetallic phases such as β-Al5FeSi or α-Alx (Fe, Mn) Si. By thermal homogenization treatment, the intermetallic compound β-Al5FeSi changes its morphology from a needle type with a monoclinic structure to an acicular form known as α-Al12(Fe, Mn)3Si with an fcc structure. In the present study, samples of the 6063 alloy were subjected to different temperatures of homogenization (798, 823, and 848 K) and treatment times from 0 to 660 min (in intervals of 30 min) to evaluate their effects on the microstructures and morphologies of the intermetallic phases. For the kinetic study, the microstructures of the β and α intermetallic phases were quantified using the Image-Pro software. The results indicate that as the temperature and homogenization time increase, the percentage of phase α also increments. The results of the kinetic analysis revealed that the β → α transformation is controlled by two stages; the first corresponds to the diffusion of Mn atoms from the matrix to the interface of reaction for the formation of the intermetallic phases, while the second corresponds to the nucleation and growth of the iron- and manganese-rich intermetallic phases. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of Cu-12.5Ni-5Sn-xY alloys with different Y addition amounts prepared using spark plasma sintering (SPS) were investigated, and the relationship was discussed. Results indicate that the addition of Y could significantly improve the mechanical properties. When 0.4 wt% Y is added, the maximum hardness and yield strength are approximately 329.5 HB and 691.9 MPa, which are approximately 31 % and 48 % higher than that without Y, respectively. The addition of appropriate amount of Y can significantly refine the grains, promote the transformation of γ-phase in the α + γ coexisting structure from lamellar-shape to needlelike-shape, and significantly inhibit the nucleation and growth of discontinuous precipitation (DP). Especially, when 0.4 wt% Y is added, the nano-scale NiY 3 particles precipitated at the grain boundary can hinder the migration of the grain boundary and occupy the nucleation sites of the γ-phases. In general, grain refinement, nano-precipitation strengthening and inhibition of DP are the main reasons for the improvement of mechanical properties. [Display omitted] • The relationship between microstructure and properties of Cu-12.5Ni-5Sn-xY alloys is discussed. • The maximum hardness and yield strength of alloy are 31 % and 48 % higher than that without Y. • When the addition of Y is 0.4 wt%, its existence is nano-scale NiY 3. • Almost no DP is observed when the addition of Y is 1.0 wt%. [ABSTRACT FROM AUTHOR]

In the paper, the effect of CoCrMoW high entropy alloy (HEA) binder in cemented carbide on the microstructure and wear-resistant and oxidation-resistant properties of the coating is investigated to provide reference for the exploration and development of new wear resistance and oxidation-resistant materials. The results indicate that the coated WC-HEA has a dense coating structure and possesses excellent high-temperature wear resistance. Compared with the Ni or Co binder phase, the coated cemented carbide containing HEA binder phase has a large difference in the matrix microstructure, cross-section morphology, mechanical properties and friction and wear properties. It is also found that a significant amount of W in the substrate diffuses through grain boundaries into the TiN coating and TiCN coatings and forms a TixWxN solid solution at the interface between the TiN coating and the matrix. In particular, the uniformity of the distribution of HEA binder in the matrix directly affects the nucleation growth of the coatings. Nanohardness results indicate that the wear resistance of TiN/TiCN/Al 2 O 3 coating is in the order of WC-Ni < WC-HEA < WC- Co. These differences come from the effect of binder on the nucleation growth and textured orientation of the coating. The comprehensive mechanical properties of the WC-HEA are similarly that of WC- Co, and it has great potential to replace WC- Co. Compared with Ni and Co binder phases, the WC-HEA coating sample is more wear-resistant at 750 °C. • The effect of CoCrMoW binder phase on the friction characteristics of coated cemented carbide are studied at different temperatures. • The friction characteristics of the coating are affected by the hardness difference between the coating and the substrate. [ABSTRACT FROM AUTHOR]

A phase field model is developed to study the discontinuous (cellular) precipitation (DP) reaction in a hypothetical A-B miscibility gap system. Unlike previous treatments, the model employs an interaction energy term which couples the composition and the phase field variable to enable the necessary grain boundary movement. The influence of factors such as interaction energy, interfacial mobility and grain boundary diffusivity on the transformation rate and overall microstructure evolution are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Discontinuous α-Cr precipitates grew along the Ni twins and stacking faults. • The cell growth rate was influenced by the wetting of grain boundaries. • The growth mechanism of discontinuous precipitation was restated. The Growth of discontinuous precipitates (DPs) is crucial in alloys that are strengthened by the DPs. Our research has demonstrated that DPs nucleate at grain boundaries and grow along twins and stacking faults in the (1 1 1) direction as a result of the twinning effect. Moreover, the growth rate is influenced by the wetting of grain boundaries. It restates how DPs evolute and provides a strategy by manipulating twins and stacking faults. [ABSTRACT FROM AUTHOR]

This study proposes a two-scale model for tricalcium silicate (C 3 S) hydration to examine the microstructure of hydrated C 3 S paste. The needle-like morphology of a calcium silicate hydrate (C-S-H) layer, as observed in many studies, was constructed using this model based on the assumption of C-S-H needles. The boundary nucleation and growth pattern of the C-S-H needles were illustrated, and the impingement among C-S-H needles and particles was considered. The pore size distribution was calculated using the rolling sphere method for the hydrated particle system and C-S-H layer. The simulation results were compared with existing experimental data, revealing consistency for the C 3 S paste with different hydration times. The shape and growth parameters of the C-S-H needles were studied to model their microstructure. The microstructure constructed using this model was found to be more reasonable and could provide a more accurate description of the C-S-H morphology. [ABSTRACT FROM AUTHOR]

The stratigraphic variation of plagioclase grain shape in the marginal regions of tabular bodies of magma provides a record of the balance of heat loss into the surroundings and heat brought into the body by magma flow during inflation and propagation. This record has the potential to constrain the amount of magma flow past any point in a sill, enabling mapping the construction of any extensive sill network. The variation of plagioclase grain shape in lava lakes may preserve a detailed history of lake filling, whereas the history of inflation of a thick ponded flood basalt flow is likely to be lost by melt-back of any early formed chill during prolonged flow at the base. Convection sufficiently vigorous to entrain crystals from the marginal solidification fronts is recorded by stratigraphic invariance of plagioclase grain shape and is not generally found in sills: instead, plagioclase grain shape varies with stratigraphic height, attesting to a predominance of in situ plagioclase nucleation and growth at the intrusion margins. While the stratigraphic variation of plagioclase grain shape in sills thinner than ~100 m is symmetrical, that in thicker sills varies in an asymmetric way with stratigraphic height, suggestive of a slower rate of inwards propagation of the roof solidification front compared to the floor, most likely indicative of moderately vigorous convection. Sills are generally finer grained than dykes of the same thickness, regardless of whether the spatial variation of plagioclase shape is consistent with convection during solidification: this is likely to be a consequence of a greater extent of Ostwald ripening of suspended grains during long-lived convection in vertically extensive dykes. [ABSTRACT FROM AUTHOR]

The mechanical properties of nanocrystalline pure Ni films are degraded due to grain coarsening with exposure for a long time in ambient. In order to further improve the mechanical properties of Ni-based thin films, as-sputtered Mo-W co-doped Ni/Ni3Al multilayered structures were constructed. When the individual layer thickness (h) is lower than 40 nm, both the average grain sizes and the crystallinity degrees are degraded, showing a tendency for the formation of the amorphous phase. With h = 40 nm, nano-twins were observed as (111) twining interfaces for the multilayers due to the reduction of the stacking fault energy by the co-doping of Mo-W, whereas the nucleation and growth of the nano-twins were limited, without observations for the Mo-W co-doped Ni/Ni3Al multilayer with h = 10 nm. The hardness of the multilayers was enhanced, and the elastic modulus was reduced at a lower h, owing to the grain refinements and layer interface barriers for strengthening, and the existence of the amorphous phase with the inferior modulus, respectively. The resistance against the fracture was enhanced due to toughening by the lamellar structure for the Mo-W doped Ni/Ni3Al multilayer at h ≤ 40 nm. Comprehensively, the Mo-W-doped Ni/Ni3Al multilayer with 10 nm displays a superior mechanical performance. [ABSTRACT FROM AUTHOR]

Here, we report on fracture behaviors of Al–Mg–Si alloys (LT21 Al) decommissioned from a research reactor in service for 30 years. Microscopic characterizations show that the initial microstructures of the long-term low-dose-rate neutron-irradiated LT21 Al are dominated by a large number of micrometer-sized voids and second-phase particles, different from short-term high-dose-rate neutron-irradiated materials. Quasi-static tensile and shock spall experiments on the irradiated and unirradiated LT21 Al reveal considerable irradiation-induced softening (larger than 40%) in both the tensile and spall strength. We attribute the irradiation softening to the over-aging process promoted by irradiation enhanced diffusion during the long-term service. Postmortem characterizations on shock-recovered samples indicate that the long-term low-dose-rate neutron irradiation-induced microstructures (micrometer-sized voids and second-phase particles) facilitate nucleation and growth of the dynamic damage in irradiated materials, thus playing an important role in the change in facture behaviors. [ABSTRACT FROM AUTHOR]

The effects of different size and number distributions of particles after intermediate annealing treatment on the final microstructure, texture and formability of Al–Mg-Si-Zn alloy after solution treatment were systematically investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometer (XRD) and tensile testing machine. The results indicated that there were significant differences in grain size and the texture intensity and volume fraction of the CubeND {001} < 310 > texture of three alloy sheets (annealed at different heating and cooling rates) after solution treatment due to the effect of different particle sizes and number distribution on the nucleation and growth of recrystallized grains. As a result, the recrystallized grain nucleation and growth mechanisms of those three alloy sheets were established, and the relationship between microstructure, texture and formability was analyzed. In addition, the distribution of the size and number of particles formed by annealing treatment with rapid heating (heating rate of 70 °C/min) and air cooling was more favorable to the formation of finer recrystallized grains and weaker texture, so that the sheet obtained higher average plastic strain ratio r ¯ values and lower anisotropic index Δr values, which improved the formability. [ABSTRACT FROM AUTHOR]

Microstructures and mechanical properties of Al-5Zn-2.6Mg alloys with 0.24, 0.43, and 0.91 wt.% Cu were studied and the precipitation rate and activation energy at 378, 393, and 408 K were calculated using the Arrhenius equation in this work. The aging reaction rate k increased and the precipitation activation energy Ea decreased from 25.7 to 15.0 kJ/mol. The η' distribution density of the precipitates clearly increased with increasing Cu content. However, the size and number of coarse second phase with Fe and Mn impurities also increased, which increased the tendency for crack initiation and propagation at the grain boundary, resulting in a decrease in dimple area. The fracture morphology transformed from plastic transgranular fracture to brittle intergranular fracture and the elongation of the alloys decreased by 3.8%. The contribution of Cu content to yield strength was predominantly due to precipitation strengthening rather than grain boundary strengthening and solid solution strengthening. The tensile strength of the Al-5Zn-2.6Mg alloys with 0.91 wt.% Cu subject to peak aging at 393 K increased by 10.2%. [ABSTRACT FROM AUTHOR]

The microstructure and kinetics of discontinuous precipitation in Cu–3.2Ti–0.2Fe–xV (x = 0, 0.1, 0.2 and 0.3 wt.%) alloys aged at 723, 773, 823 and 873 K were studied by using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS), with the help of CALculation of PHAse Diagram (CALPHAD) method and Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation. The volume fraction of Laves_C14 was increased with raising V content, leading to the effective grain refinement during casting and the inhibiting grain growth in solution treatment process. The activation energies of Cu–3.2Ti–0.2Fe–xV (x = 0, 0.1, 0.2 and 0.3 wt.%) alloys were 196.4, 172.9, 147.4, 154.1 kJ mol−1, respectively. The discontinuous precipitation was promoted and controlled by grain boundary diffusion in the early stages at low temperature, while it was inhibited by bulk diffusion at high temperature or in the later stages at low temperature. In addition, the peak-aged hardness was improved with proper amount of V addition due to the strengthening of Laves_C14 and grain refinement, as well as the inhibition of discontinuous precipitation.

In the present study, Mo was added to Cu–15Ni–8Sn alloy as the fourth element to solve the limitation of service performance of the alloy by composition design. The phase composition, microstructure transformation and mechanical properties of Cu–15Ni–8Sn–xMo (x = 0.3, 0.9, 1.5 wt.%) alloy were systematically studied by simulation calculation and experimental characterization. The results show that the addition of Mo can improve the as-cast structure of Cu–15Ni–8Sn alloy and reduce segregation and Cu–Mo phase precipitates on the surface with the increase in Mo contents. During solution treatment, Mo can partially dissolve into the matrix, which may be the key to improving the properties of the alloy. Furthermore, the discontinuous precipitation of Sn can be effectively inhibited by adding the appropriate amount of Mo to Cu–15Ni–8Sn alloy, and the hardness of alloy does not decrease greatly after a long-time aging treatment. When Mo content is 0.9 wt.%, the alloy reaches the peak hardness of 384 HV at 4 h of aging. These results provide new ideas for composition optimization of Cu–15Ni–8Sn alloy. [ABSTRACT FROM AUTHOR]

Taking the high volume fraction SiCp/6061Al-based composite material prepared by the powder metallurgy method under different sintering temperatures and holding times as the research object, the microstructure and interface actions are investigated by X-ray diffractometer, scanning electron microscope, transmission electron microscope, etc. The results show that as the sintering temperature increases, the interface reaction between SiC and Al intensifies, producing brittle phase Al4C3 and MgAl2O4 and MgO interface products. The nucleation and growth of Al4C3 are controlled by the sintering temperature and time. When preparing large-size workpieces with high volume fraction SiCp/6061Al-based composite materials, the sintering temperature should be controlled below 6 7 0 ∘ C, and the holding time should not exceed 24 h. [ABSTRACT FROM AUTHOR]