945 results about "Grain boundary" patented technology

The invention discloses an yttrium-rich neodymium-iron-boron magnet and a preparation method thereof, and belongs to the technical field of rare earth permanent magnet material preparation. The preparation method comprises the following steps: mixing yttrium-rich neodymium-iron-boron matrix alloy powder with grain boundary doped alloy powder containing Gd and / or Ho, and carrying out compression molding and sintering tempering treatment to obtain a first yttrium-rich neodymium-iron-boron magnet. According to the invention, the grain boundary doped alloy powder containing Gd and / or Ho is added into the yttrium-rich neodymium iron boron matrix alloy powder and then is sintered, so that a continuous and uniform non-magnetic thin-wall grain boundary phase structure is formed in the grain boundary, and the coercive force of the magnet is enhanced. Dy and / or Tb heavy rare earth element grain boundary diffusion is carried out based on the first yttrium-rich neodymium-iron-boron magnet after grain boundary modification, a second yttrium-rich neodymium-iron-boron magnet is obtained, the diffusion depth of Dy and / or Tb in the magnet can be increased, the utilization rate can be increased, the cost can be reduced, the coercivity of the magnet can be improved, and the adverse effect of Dy and / or Tb on residual magnetism can be reduced.

The invention discloses a method for improving performance of rare earth permanent magnet sintered neodymium iron boron grain boundary diffusion, and belongs to the technical field of rare earth permanent magnet materials. The method comprises the steps that a low-melting-point metal layer and a diffusion layer containing heavy rare earth elements are sequentially formed on the surface of a clean sintered neodymium-iron-boron magnet, and then vacuum diffusion heat treatment and tempering treatment are conducted. Wherein the low-melting-point metal layer comprises at least one of copper, aluminum, gallium and tin or an alloy of the copper, the aluminum, the gallium and the tin; the heavy rare earth element comprises at least one of dysprosium, terbium, holmium and gadolinium. The low-melting-point metal layer is preferentially diffused and wets the grain boundary in the heat treatment process, heavy rare earth elements are promoted to be deeply and uniformly diffused towards the interior of the magnet along the grain boundary, so that a heavy rare earth-rich shell layer is formed outside main phase grains of the magnet, and the intrinsic coercive force is improved; meanwhile, the low-melting-point metal forms a strengthening phase at the grain boundary, the brittleness of the magnet after diffusion is improved, the surface corrosion phenomenon is restrained, and collaborative optimization of the comprehensive performance of the magnet is achieved.

The invention provides a nickel-based rare earth composite powder material for high-speed laser cladding and a preparation method of a nickel-based rare earth composite coating, and relates to the technical field of laser cladding and metal surface modification. The nickel-based rare earth composite coating takes Inconel 625 nickel-based alloy as a matrix phase material; a trace amount of rare earth oxide Y2O3 is introduced into a powder system to serve as a second phase enhancing component, and the material is prepared and formed at a time under the condition of a high-speed laser cladding process; in the high-speed laser cladding process, due to high scanning speed, low heat input per unit length and high cooling rate, metal liquid in a molten pool has the characteristic of rapid solidification; the rare earth oxide Y2O3 can stably exist in a molten pool, the particle surface of the rare earth oxide Y2O3 provides a large number of heterogeneous nucleation cores for the alloy solidification process, meanwhile, grain growth is restrained through the grain boundary pinning effect, and therefore the solidification structure form of the nickel-based cladding coating is remarkably improved.

The invention discloses a corrosion-resistant copper alloy pipe. The corrosion-resistant copper alloy pipe comprises the following components in percentage by mass: 0.05-0.40% of P, 0.001-0.1% of X, and the balance of Cu and inevitable impurities, wherein the X is selected from at least one of Al, Ni or RE; in the structure of the copper alloy pipe, the volume fraction of the small-angle grain boundary is 40-65%, and the volume fraction of the large-angle grain boundary is 25-50%. The copper alloy pipe has good corrosion resistance and oxidation resistance, and meanwhile beneficial bending, flaring, welding and pressure resistance are guaranteed. The invention further discloses a preparation method of the copper alloy pipe. The technological process of the preparation method comprises the steps of smelting, casting, face milling, rolling, stretching, rewinding and secondary annealing. Wherein the secondary annealing temperature is 350 to 580 DEG C, and the annealing time is 0.5 to 3.5 hours. The invention further discloses application of the copper alloy pipe and the copper alloy pipe prepared through the preparation method to preparation of a heat conduction pipe of an air conditioner heat exchanger, an air conditioner indoor and outdoor unit connecting pipe or a built-in pipe or a pipe assembly.

The invention relates to preparation of a ZTA composite ceramic material, and belongs to the field of inorganic nonmetal composite materials. The raw material composition formula comprises aluminum oxide, zirconium oxide, zirconium dioxide, yttrium oxide, magnesium oxide and titanium dioxide. The low-sodium microcrystalline alumina powder with the original grain size of 0.40 [mu] m is selected and ground to the original grain size in advance, so that zirconia can be more uniformly distributed between alumina grain boundaries, which is a precondition for obtaining more uniform ZTA. Zirconium dioxide is creatively introduced, and compared with a conventional method in which stable zirconium oxide is directly used, the cost of ZTA is greatly reduced. The pre-calcined granulation powder is adopted, so that a ZTA product which is uniformly mixed in the early stage is cured by adding a stabilizer, and then the uniform and stable ZTA ceramic can be obtained through later-stage forming and firing.

The invention provides a Y-rich rare earth permanent magnet and a preparation method and a magnetic performance improving method thereof, and the performance improving method comprises the steps: uniformly mixing to-be-diffused metal powder containing Dy and / or Tb elements with an organic solvent to obtain to-be-diffused alloy liquid; the alloy liquid to be diffused is attached to the surface of the Y-rich rare earth permanent magnet, and the Y-rich rare earth permanent magnet is placed in a vacuum sintering furnace; the Y-rich rare earth permanent magnet is subjected to grain boundary diffusion heat treatment through the vacuum sintering furnace, so that Dy and / or Tb elements are diffused into the surface layer of a main phase lattice of the Y-rich rare earth permanent magnet; and carrying out tempering treatment on the Y-rich rare earth permanent magnet. The problems that the coercive force of an existing Y-containing magnet is difficult to effectively improve, and residual magnetism is easily reduced can be effectively solved.

The preparation method of the A1-grade nondestructive inspection high-impact-toughness TC4 titanium alloy large-size bar comprises the steps that a secondary finished product cast ingot is subjected to a multi-heating-number high-temperature single-phase beta-region large-deformation forging process in the cogging stage, and as-cast grains are fully crushed and refined in the modes of axial upsetting, lateral upsetting, diagonal upsetting and the like; then, high-low-high-low repeated forging is conducted at the temperature above and below the phase transformation point, grain homogenization is achieved through high-temperature dynamic recrystallization, an original grain boundary is eliminated, and deformation dead zones of a corner angle area are effectively reduced in combination with multi-heating-number diagonal drawing-out forging; and finally, multi-heating-number forging is conducted in the two-phase region, a heat treatment process is combined, the microstructure form is further optimized, and a lamellar alpha structure is controlled to guarantee the low-temperature impact performance. According to the method, the structure uniformity of the TC4 alloy bar can be remarkably improved, the A1-level nondestructive testing requirement is met, and the method has excellent axial and chordwise mechanical properties and is suitable for ocean equipment and other high-end application fields with strict requirements for the comprehensive performance of materials.

The invention relates to the technical field of ceramic manufacturing processes, and particularly discloses a preparation method of a 96 aluminum oxide ceramic substrate, which comprises the following steps: slurry preparation: carrying out ball milling treatment on high-purity aluminum oxide powder, a sintering aid, a binder, a plasticizer, an organic solvent and a dispersing agent, and fully mixing to obtain tape casting slurry; forming a green body, coating a carrier film with the tape casting slurry through a tape casting machine with a wet film which is uniform in thickness and flat in surface, and drying the carrier film through a drying box in a partitioned manner to obtain a cured green body; and sintering densification treatment: carrying out glue removal treatment on the green body, and carrying out stepped heating sintering to obtain the 96 aluminum oxide ceramic substrate. According to the 96 aluminum oxide ceramic substrate prepared by the scheme, a large number of uniform crystal cores can be formed, small crystal grains can be dissolved, large crystal grains grow at a constant speed, and the uniformity of the crystal grain size is ensured, so that scattering of phonons on a crystal boundary can be reduced, and a structural foundation is laid for improvement of heat conductivity.

The invention provides a sulfide electrolyte material and a preparation method and application thereof, and the preparation method comprises the following steps: mixing lithium sulfide, phosphorus pentasulfide, rare earth sulfide and a solvent, and reacting to obtain a sulfide electrolyte precursor; and carrying out pressing treatment on the sulfide electrolyte precursor, and carrying out low-temperature sintering on the material obtained by pressing at 250-500 DEG C to obtain the sulfide electrolyte material. According to the method disclosed by the invention, the synthesis of the rare earth element doped sulfide precursor is realized by adopting a pure liquid phase method, particles are dispersed in a liquid phase solvent, and the particle uniformity and dispersity of the obtained finished product are obviously superior to those of a solid phase method. After the precursor obtained by the liquid phase method is pressed and sintered at low temperature, the crystal boundary between crystals of the electrolyte material is relatively small, the energy barrier of ion transmission is remarkably enhanced, the conductivity of the electrolyte is optimized, and the long-cycle stability of the all-solid-state battery is improved.

The invention provides a grain boundary diffusion neodymium iron boron magnet and a preparation method thereof, and relates to the technical field of magnetic materials. The preparation method comprises the steps of surface pretreatment and purification, precise diffusion source construction through magnetron sputtering and diffusion promotion through vacuum heat treatment. The core function of pretreatment is to remove surface impurities and lay a foundation for subsequent deposition of alloy films; the proportion of Tb, Al and Cu in a diffusion source is accurately regulated and controlled in the magnetron sputtering stage, and the synergistic effect is achieved; and the vacuum heat treatment promotes Tb to diffuse into the neodymium iron boron. According to the method, a technical closed loop with pretreatment as a basis, a diffusion source as a core and heat treatment as power is formed, the microstructure of the neodymium-iron-boron magnet is optimized, a complete and continuous shell structure with the moderate thickness is formed, the diffusion depth of heavy rare earth is greatly increased, and the service life of the neodymium-iron-boron magnet is prolonged. Finally, the coercive force of the neodymium-iron-boron magnet is remarkably improved, and the utilization rate of heavy rare earth elements is effectively improved. The problem of low Tb utilization rate in the prior art is solved, and the bottleneck of coercive force improvement is broken through.

A ferrite structure edge extraction method based on a microstructural phase diagram of steel, comprising: performing edge detection on a metallographic image of a low-carbon steel cold rolled sheet; closing grain boundaries; removing redundant boundaries; detecting grain parts of unconnected parts and grain unclosed parts in a labeled image on the basis of a network topology structural diagram, performing grain boundary edge determination, and when the vertex of each unclosed part grain remains unchanged, continuously traversing different grain boundary arcs connected to the unclosed part grain so as to determine whether the unclosed part grain satisfies the characteristics of a completely closed grain, thereby achieving grain reconstruction; and then performing reconstruction detection to finally complete extraction and reconstruction of ferrite structure edges. Thus, ferrite grains of a microstructural phase diagram of steel are accurately reconstructed, two grains connected by a narrow area are effectively segmented, accurate ferrite grains of a low-carbon steel cold rolled sheet can be extracted, and ferrite grain size grading of the low-carbon steel cold rolled sheet is assisted on the basis of the extracted accurate ferrite grains of the low-carbon steel cold rolled sheet.

The invention provides a treatment method for synergistically enhancing the comprehensive performance of a neodymium-iron-boron magnet, and belongs to the technical field of magnetic materials. According to the method, a heavy rare earth layer and a corrosion-resistant metal layer such as copper, nickel and cobalt for promoting grain boundary diffusion of heavy rare earth are respectively deposited on the surface of the neodymium-iron-boron magnet by adopting a multi-layer electroplating method, the coercivity of the neodymium-iron-boron magnet is enhanced through grain boundary diffusion, and the corrosion resistance of the magnet is enhanced through a nickel-cobalt coating. The treatment method comprises the following steps: carrying out electrochemical deposition on the neodymium-iron-boron magnet in a heavy rare earth metal plating solution, and then respectively electroplating a copper plating layer and a nickel-cobalt plating layer to obtain a heavy rare earth-containing plating layer with strong corrosion resistance and good plating film binding force; the neodymium-iron-boron magnet containing the heavy rare earth coating is subjected to heat treatment, and the coercive force of the magnet is improved through heavy rare earth grain boundary diffusion. The neodymium iron boron grain boundary diffusion process and the surface corrosion prevention process are subjected to integrated treatment, the technological process of high-performance neodymium iron boron industrial preparation is shortened, and the coercive force and the corrosion resistance of the magnet are comprehensively enhanced.

The invention discloses a double-perovskite thin film material, a preparation method thereof and a double-perovskite solar cell, and relates to the technical field of perovskite materials. The double perovskite thin film material comprises A2BCX6 type double perovskite, A is an alkali metal cation, B is a monovalent metal cation, C is a trivalent metal cation, and X is a halogen anion; the additive is a compound comprising a benzene ring and at least two sulfydryl substituted at different positions of the benzene ring. According to the embodiment, the composite center of the interior and interface of the double-perovskite thin film material can be reduced, the nucleation density in the preparation process of the double-perovskite thin film is reduced, the double-perovskite film layer has high crystallinity and larger grain size, the grain boundary in the film layer is reduced, the grain boundary defect is passivated, and the performance of the double-perovskite thin film is improved. And the photoelectric conversion efficiency of the solar cell containing the double perovskite thin film material can be improved.

The present invention relates to a method for manufacturing a grain boundary diffusion material using a rare earth oxide and a method for manufacturing an R-Fe-B-based permanent magnet using the same, whereby an inexpensive grain boundary diffusion material can be manufactured using a rare earth oxide that is less expensive than an expensive rare earth metal. In addition, an R-Fe-B based permanent magnet in which grain boundary diffusion is performed using a grain boundary diffusion material made of a rare earth oxide can exhibit excellent coercive force.

The invention discloses a preparation method of a sintered neodymium-iron-boron magnet without heavy rare earth, Pr-Fe-B-M alloy is used as an auxiliary phase alloy, LRe-Fe-B-M alloy is used as a main phase alloy, the auxiliary phase alloy is used for preparing a magnet matrix and performing grain boundary diffusion at the same time, the magnet without heavy rare earth is prepared, praseodymium element is non-uniformly distributed in the magnet, and rare earth element is not uniformly distributed in the magnet. The Pr content of part of the main phase is higher than the overall average content, the crystal boundary praseodymium content is higher than the overall average content, and the magnet surface praseodymium content is higher than the overall average content. The coercive force and the temperature stability of the magnet are improved, the magnet can still keep excellent magnetic performance under the condition that Dy and Tb are not contained, heavy rare earth elements such as Dy and Tb which are scarce in resource and high in price are prevented from being used, the high performance of the magnet is guaranteed, the production cost is reduced, and the resource utilization efficiency is improved.

The invention discloses an equivalence evaluation method for testing the fracture behavior of an irradiation metal material based on a small sample, belongs to the field of mechanical property testing, and deeply researches the size effect problems of non-uniform deformation and crack initiation of the metal material under the irradiation condition through three research means of experiments, theories and simulation. And a powerful basis is provided for performance evaluation of the metal material under the irradiation condition. In the aspect of experiments, micro-stretching and micro-cantilever beam experiments of samples with different sizes under irradiation conditions are carried out, and a correlation mechanism between irradiation material crack initiation and sample sizes is analyzed. On the theoretical aspect, a dislocation channel-grain boundary interaction model is established, and prediction of fracture toughness of irradiation samples of different sizes is achieved. In the aspect of simulation, a finite element simulation system for non-uniform deformation, crack initiation and size effect of the metal material under the irradiation condition is established, and the influence of irradiation and sample size on microstructure evolution and macroscopic fracture behavior of the material is explored.

The invention belongs to the technical field of material image recognition and processing, and provides a metallographic microscopic image structure classification method based on multi-scale structure feature extraction. The method comprises the steps of microscopic image acquisition, preprocessing, defect suppression, multi-scale structural feature extraction, feature fusion, dimension reduction and classification judgment, integration of grain boundary, texture and morphological features, defect repair by adopting PatchMatch texture synthesis, and reduction of the influence of scratches, uneven corrosion and the like on precision. Feature fusion supports weight adaptive distribution, and a classifier can be a support vector machine (SVM) or a lightweight convolutional neural network (preferably MobileNet). The system is composed of an acquisition module, a preprocessing module, a defect detection and repair module, a feature extraction module, a fusion and dimension reduction module and a classification judgment module, can be in butt joint with a required platform, realizes online detection, automatic classification and result archiving, is suitable for metal and non-metal material microscopic structure classification, and has a good application prospect. Wherein the non-metallic material can increase porosity calculation, fiber direction distribution and other morphological characteristic analysis.

The invention belongs to the technical field of metal materials, and particularly relates to a method for synergistically inhibiting residual elements from deteriorating the performance of ultrathin steel through microalloying. According to the invention, trace amounts of Nb, Ti and other strong carbonitride forming elements are added, and 0.008%-0.012% of precise S is added, so that the elements are matched with Ti to form Ti4S2C2 composite inclusions, and the phase can keep stable form in the rolling process and is prevented from being stretched along the rolling direction, thereby effectively inhibiting harmful segregation of residual elements at the grain boundary, and improving the quality of the product. The high-strength, high-toughness, high-conductivity and low-loss performance of the material are improved, and a material basis is provided for promoting high-quality development of 5G infrastructures.

The invention discloses a cerium-containing high-abundance rare earth sintered neodymium iron boron permanent magnet which does not contain heavy rare earth and does not need a grain boundary diffusion process and a preparation method thereof. The magnet is formed by crushing and mixing three alloy casting pieces, the three alloy casting pieces are an Nd / Pr-rich phase, a Ce-La-rich phase and a Y-Nd-rich phase respectively, and Ce accounts for more than or equal to 30wt% of the total amount of all rare earth elements; the trace elements (Al, Cu, Ga, Nb, Zr and the like) are uniformly introduced in the smelting stage of each main phase, and grain boundary reconstruction is induced through in-situ hydrotreating to form a thin and continuous rare earth-rich grain boundary phase; and after orientation compression molding, vacuum sintering and multi-stage heat treatment, a sintered magnet with excellent magnetic performance is obtained. According to the product, the intrinsic coercive force Hcj is larger than or equal to 15 kOe, the residual magnetism Br is larger than or equal to 13.7 kG, and the maximum magnetic energy product (BH) max is larger than or equal to 39 MGOe. The problems that a high-Ce magnet is low in coercive force, discontinuous in grain boundary phase and the like are solved, the method does not need to depend on Dy / Tb heavy rare earth and a grain boundary diffusion technology thereof, the cost is reduced by 30% or above, and the method is suitable for the fields of new energy automobiles, wind power generation and the like and has a good industrialization prospect.

The invention provides a high-entropy rare earth doped WC hard alloy and a preparation method and application thereof, and belongs to the technical field of alloys. The precursor is prepared through wet codeposition, compared with ball-milling mixing, atomic-scale dispersion can be achieved, rare earth segregation can be avoided, high-entropy rare earth nano-particles are distributed in WC crystals and pinned in WC crystal boundaries, dislocation movement is hindered, meanwhile, WC is doped with high-entropy rare earth, all elements in the high-entropy rare earth act synergistically, the hardness and strength of the alloy are improved, and the performance of the alloy is improved. And compared with chemical plating, Co is plated through magnetron sputtering, the interface bonding strength can be improved, introduction of impurities is avoided, and the hardness and strength of the alloy are further improved. The result of the embodiment shows that the hardness of the prepared high-entropy rare earth doped WC hard alloy is 93.9 HRA or above, and the bending strength is 2980 MPa or above.

The invention discloses a machine learning-based grain boundary twinning behavior prediction method, which comprises the following steps of: firstly, analyzing microscopic structure data of a deformed sample, extracting parameters related to grain boundaries to calculate 15 characteristic parameters related to grain boundary twinning behaviors, and marking real twinning behavior types of the grain boundaries so as to construct an original characteristic data set; then, after equalization and standardization processing is carried out on the data set, the data set is divided into a training set and a test set, the training set is used for optimizing hyper-parameters of the machine learning model and training the optimized machine learning model to obtain a prediction model, and the test set is used for verifying the accuracy of an evaluation model; and finally, substituting 15 characteristic parameters of an undeformed to-be-tested sample into the prediction model so as to predict the types of twinning behaviors possibly occurring at each grain boundary after the to-be-tested sample undergoes plastic deformation. The model constructed by the method can comprehensively capture the nonlinear relationship and interaction among multiple influence factors, the prediction accuracy of the twinning behavior at the grain boundary is high, and the generalization ability is high.

The invention discloses a double-ceramic-layer thermal barrier coating of a differentiated columnar crystal structure and a preparation method, and belongs to the technical field of thermal barrier coating corrosion and protection. The invention innovatively discovers and utilizes the double influence of the columnar crystal size on the performance of the coating; the YSZ layer adopts a fine grain structure of 1-1.5 microns, so that the bonding strength and thermal shock resistance of the coating can be obviously improved; and the modified gadolinium zirconate layer adopts a 2-3 [mu] m coarse grain structure, so that the heat conductivity can be reduced, the permeation path of CMAS along a grain boundary can be effectively inhibited, and meanwhile, the modified gadolinium zirconate layer reacts with CMAS to form a compact barrier layer to prevent further permeation of CMAS. Through accurate regulation and control of electron beam physical vapor deposition (EB-PVD) process parameters, differential control of the sizes of the two layers of ceramic columnar crystals is realized, and under the synergistic effect of the two columnar crystal structures with different sizes, the thermal cycle life and CMAS corrosion resistance of the whole coating system in an ultra-high-temperature environment are remarkably prolonged and improved.

The invention relates to the field of regenerated magnetic materials, in particular to a process for recycling a regenerated neodymium iron boron magnet from waste neodymium iron boron. The invention discloses a process for recycling and regenerating a neodymium iron boron magnet from waste neodymium iron boron. The process comprises the following steps: preparing Tb-HoBiO3 powder; pretreating the waste neodymium iron boron; pretreating the waste neodymium iron boron to prepare a blank body; and carrying out low-temperature supergravity sintering impurity removal and tempering treatment on the blank. According to the method, the Tb-HoBiO3 powder is prepared, and the Tb-HoBiO3 powder can better promote the uniform transformation of a blocky grain boundary phase into a strip shape and wrap the periphery of a grain main phase in the blank sintering process, so that local stray fields in the main phase grains and the magnet can be isolated, the demagnetization resistance of the regenerated neodymium-iron-boron magnet is remarkably improved, and the service life of the regenerated neodymium-iron-boron magnet is prolonged. Therefore, the magnetic performance of the regenerated neodymium-iron-boron magnet is improved, main phase crystal grains can be effectively prevented from falling off, the density of the regenerated neodymium-iron-boron magnet is improved, microdefects are reduced, the corrosion resistance of the regenerated neodymium-iron-boron magnet is remarkably improved, and the service life of the regenerated neodymium-iron-boron magnet can be prolonged.

The invention discloses a neodymium-iron-boron rare earth permanent magnet, a preparation method and use thereof. The neodymium-iron-boron rare earth permanent magnet comprises: R: 28.5-33 wt %, wherein RL comprises Pr, Pr≥14 wt %, and RH comprises one or more of Dy, Tb, Gd and Ho; Co: 12-20 wt %; Al: 0.5-1.5 wt %; X: 0.3-1.5 wt %; B: 0.88-1.05 wt %; and a balance of Fe, the microstructure thereof comprises a main phase M, a grain boundary phase A and a grain boundary phase B; the main phase M is R2(Fe, Co)14B having a volume percentage of 90-94%; the grain boundary phase A is R(Fe, Co)2 having a volume percentage of 5-8%; and the grain boundary phase B is R4(Fe, Co)3 having a volume percentage of 1-2%. The neodymium-iron-boron rare earth permanent magnet has a high Co content, a high Curie temperature, a low temperature coefficient, good mechanical properties, a high magnetic energy product and a high coercive force.

The invention discloses a twin crystal nucleation position and variant selection prediction method based on machine learning, and belongs to the crossing field of material science and machine learning. The method comprises the following steps: acquiring microscopic structure data of a deformation material through electron back scattering diffraction, and constructing a multi-dimensional data set containing crystal grain parameters, crystal boundary parameters and deformation mechanism parameters by taking crystal grains and a certain crystal boundary combination as an analysis unit; and then modeling and predicting the twin crystal nucleation position and variant selection respectively by adopting a hierarchical machine learning modeling strategy. According to the method, the twinning behavior in the polycrystalline material can be efficiently and accurately predicted, and theoretical support and a technical path are provided for high-performance metal material design and plastic deformation mechanism research.

The invention discloses a residual creep life prediction method based on microscopic damage characteristics. The residual creep life prediction method comprises the following steps: acquiring interrupt samples in different damage states through a creep interrupt test; quantitatively characterizing the grain boundary orientation difference and the geometric necessary dislocation density of the interrupted sample by using an electron back scattering diffraction technology; a quantitative damage index is constructed based on the grain boundary orientation difference and the geometric necessary dislocation density, the quantitative damage index is used as an internal variable to be coupled into a Marson-Miller parameter model, and a microscopic-macroscopic associated residual life prediction model is established; and through a microscopic-macroscopic associated residual life prediction model, predicting the residual life of the material under different service times to obtain the residual creep life. According to the method, the microscopic damage state in the material can be directly and quantitatively reflected, early, sensitive and accurate prediction of the residual creep life of the in-service component is realized, and a reliable basis is provided for safe operation and maintenance decision of an overdue service unit of a power plant.

The invention relates to the technical field of photocatalytic materials, in particular to a multi-ion doped TiO2 nanosheet material suitable for degradation of dyes in water and a preparation method of the multi-ion doped TiO2 nanosheet material. The preparation method comprises the following steps: pre-embedding a self-sacrifice template in a germanium-tungsten composite doping solution, carrying out hydrothermal conversion to construct a Ge-W synergetic optimized regular TiO2 substrate, carrying out atomic layer deposition to realize nitrogen / silver uniform doping, and carrying out synergetic surface modification on silver nitrate-ethanolamine and perfluorosilane to prepare the TiO2 nanosheet material. Germanate serves as lattice strain guidance to guide TiO2 lattice growth to form a low-defect matrix, tungstate is cooperatively doped in the matrix to construct a strong built-in electric field to improve the charge separation efficiency, Ge-W elements cooperate to stabilize a bulk phase and a grain boundary, and a gradient protection barrier is constructed with selective shielding of a fluorosilane layer. The TiO2 catalyst is synergistically improved in the aspects of high catalytic activity and long-acting environmental stability, and is suitable for efficient pollutant purification in a complex water quality environment.

The present application belongs to the technical field of metal materials, and particularly relates to a method for in-situ measuring MC carbide solid solution and precipitation temperature by internal friction. The present application uses pure iron and pure chromium to prepare Fe-Cr based alloy samples, processes the samples into internal friction samples after solid solution and rolling; in a vacuum environment, the samples are heated to a preset target temperature covering the expected solid solution characteristic temperature range of MC carbide at a constant rate and are kept at the temperature, then are cooled at the same rate, the internal friction value and modulus are continuously measured, and a first and second in-situ internal friction temperature spectrum is drawn; the frequency dispersion characteristics of grain boundary relaxation peak, the internal friction value mutation and the modulus change in the two temperature spectra are compared to determine the solid solution temperature and precipitation temperature of MC carbide. The method has high sensitivity and simple operation, and is suitable for in-situ characterization of grain boundary precipitates in low carbon content Fe-Cr based alloys.

The application discloses a silicon carbide grain size detection method based on image processing and relates to the technical field of semiconductor material quality detection. A first feature map is generated by calculating the phase consistency distribution of a silicon carbide metallographic image to suppress scratch interference. A topological anchor sequence is identified by using the eigenvalues of a Hessian matrix, and a balanced first gradient potential field matrix is generated by combining local entropy density to suppress polycrystalline contrast fluctuation. Under the constraint of the topological anchor, an optimization evolution is performed by using a path cost function with curvature penalty and energy saturation characteristics, physical inertia closure of a grain boundary signal fracture is realized, and a closed grid vector is generated. Twin grain boundaries are identified and logically merged based on geometric parameters, and grain size detection data consistent with the physical structure of the material is output.

This invention provides a method and application for NdFeB grain boundary diffusion. The method includes: magnetizing diffusion source alloy powder to impart different magnetic properties; spontaneously and uniformly adsorbing the different magnetic properties of the diffusion source alloy powder onto the surface of a NdFeB magnet, forming a multi-layered diffusion source alloy layer; and then subjecting it to diffusion treatment, allowing the multi-layered diffusion source alloy powder to work synergistically and diffuse into the interior of the NdFeB magnet. The diffusion source alloy forms a shell structure on the surface of the NdFeB grains, resulting in a high-performance NdFeB magnet. This invention forms a multi-layered diffusion source alloy layer on the magnet surface through spontaneous adsorption. Thermal diffusion allows the alloy powder to fully penetrate into the magnet and bond with the surface of the NdFeB grains, thereby increasing the penetration depth of the diffusion source alloy and resulting in a significant diffusion effect, further improving the magnetic properties of the magnet. The preparation method is simple and suitable for large-scale application.