357 results about "Dislocation" patented technology

The invention belongs to the technical field of silicon carbide single crystal materials, and particularly relates to a growth device of large-size silicon carbide single crystals and a preparation method of the silicon carbide single crystals, porous graphite cylinders are arranged in a powder area of the growth device of the large-size silicon carbide single crystals, and the porous graphite cylinders are distributed along the edge of the powder area to the center in a stepped mode. The height is gradually increased from the edge to the center; a plurality of layers of stacked graphite pore plates are arranged at the top of the powder area, the upper end parts of the porous graphite cylinders are flush with the upper surfaces of the corresponding layers of graphite pore plates, and the porous graphite cylinders penetrate through the graphite pore plates, so that a continuous gas phase transmission channel from the powder area to the crystal growth area is formed. According to the invention, the plurality of porous graphite cylinders are arranged in the silicon carbide raw material area in a stepped manner, so that the temperature field distribution of the raw material area is stabilized, the gas phase layout is optimized, impurities in gas phase components are filtered, and the defects of microtubes, inclusions, dislocation and the like in crystals are improved.

The invention discloses a sample preparation and characterization method of a rotation angle crystal interface, which is suitable for a sample with dislocation at the interface of two crystals, and comprises the steps of sample preparation and measurement of the relative rotation angle theta of the two crystals. A certain angle is formed between the cutting direction and the interface for sample preparation, a slice is taken out, and the obtained slice has three thin areas including a top material A crystal, a top material A / bottom material B crystal mixing area and a bottom material B crystal; measurement of the rotation angle theta: the electron beam direction is parallel to the rotation axis of the top sample during testing, and the rotation angle theta is directly measured by analyzing crystallographic information of the three thin areas. According to the method, the rotation angle of the top crystal relative to the bottom crystal can be accurately measured through TEM analysis of the three thin regions, and the error-tolerant rate of TEM sample preparation and analysis experiments is improved. In addition, the sample preparation technology can be used for monitoring the change of the physical properties of the sample in mechanics, thermotics, optics, electricity and the like along with the reduction of the size of the sample from the micron level to the nano level.

The invention discloses a spinning forming dislocation evolution prediction and process optimization method based on multi-scale modeling, which combines three calculation methods with different scales and levels, namely macroscopic finite element simulation, microcosmic crystal plasticity simulation and microcosmic dislocation dynamics simulation. A complete perspective from macroscopic mechanical behaviors to microscale mechanical response and dislocation density evolution and then to microscale single dislocation motion and interaction mechanism can be provided, so that the plastic forming process of the metal material can be understood more comprehensively. Not only are the prediction precision and reliability improved, but also the understanding depth of the material deformation behavior and the influence factors thereof is enhanced. By integrating information of different scales, key characteristics such as macroscopic stress, strain distribution, grain deformation response, dislocation density evolution and movement and interaction of a single dislocation of the material in the plastic forming process can be predicted more accurately. Meanwhile, in combination with multi-scale simulation, process parameters can be optimized to obtain better forming quality and performance.

The invention discloses a manufacturing defect-oriented multi-scale composite material mechanical property prediction method, and belongs to the technical field of composite material mechanical property analysis. The method comprises the following steps: based on a multi-scale representative volume element (RVE) theory, respectively constructing parameterized models containing pores and fiber dislocations in a microscopic scale and a mesoscale; the equivalent elastic parameters under each scale are calculated through a finite element numerical homogenization technology, and an agent model is constructed in combination with an artificial neural network, so that the calculation cost is remarkably reduced, and the high-efficiency cross-scale prediction of the rigidity and strength performance of the composite material is realized. The method overcomes the defect of defect modeling of a traditional model, has high precision and high efficiency, and is suitable for performance evaluation and optimization design of composite material structures in the fields of aerospace, rail transit and the like.

The invention discloses a multi-scale simulation method for a thermal compression deformation behavior of TC4 titanium alloy, and belongs to the field of metal material processing simulation. Comprising the following steps: 1, carrying out thermal compression experiments at different temperatures to obtain a deformed sample; 2, analyzing the grain orientation, orientation difference angle and texture evolution of the sample by using an electron back scattering diffraction technology; 3, constructing a crystal plasticity finite element model, and simulating a polycrystalline deformation process; 4, constructing a molecular dynamics model, and simulating phase change and dislocation evolution in thermal compression and cooling processes; and 5, based on a multi-scale simulation result, hot working parameters are optimized, dynamic recrystallization and a beta-to-alpha phase change path are regulated and controlled, and grain refinement and performance homogenization are achieved. The invention discloses a correlation mechanism of the microstructure and the mechanical property in TC4 titanium alloy thermal compression deformation, and provides a theoretical basis for optimization of a thermal processing technology of a high-performance titanium alloy component in the aerospace field.

The invention relates to the technical field of defect characterization of silicon carbide single crystal substrate materials, in particular to a silicon carbide corrosion device and a working method thereof. The silicon carbide corrosion device comprises a crucible furnace, an inner lifting shaft and a basket; the crucible furnace comprises a furnace body and a furnace cover, a heating element is arranged outside the furnace body, the furnace body is provided with an oxygen inlet used for introducing oxygen and a gas discharge port used for discharging gas, the furnace cover covers the furnace body, the top of the furnace cover protrudes upwards to form an outer lifting shaft used for lifting the furnace cover, and the outer lifting shaft is provided with a through hole; the inner lifting shaft is inserted into the through hole of the outer lifting shaft, and the basket is installed at the bottom end of the inner lifting shaft and used for containing wafers. According to the method, different dislocation morphologies of the heavily nitrogen-doped substrate can be accurately distinguished, the corrosion efficiency is improved, the safety of operators is guaranteed, meanwhile, the operation process is simplified, and large-scale popularization and application are facilitated.

The invention discloses a method for improving the strength and plasticity of a middle-high layer staggered energy metal material, and belongs to the technical field of metal material preparation and processing. According to the method, N times of deep cooling online treatment (N is larger than or equal to 2) are carried out on the middle-high layer staggered energy metal material, a deep cooling medium is liquid nitrogen or liquid helium, plastic deformation is achieved by means of continuous rolling and other processes, and online aging heat treatment can be carried out between the treatment chambers. After treatment, the material forms a nano twin crystal structure, so that the strength and plasticity are synergistically improved, and the high conductivity is kept. According to the method, the limitation of a traditional strengthening technology is broken through, dislocation motion and stress distribution are regulated and controlled through the nano twin boundaries, fracture is avoided, and the conductivity is guaranteed. Meanwhile, the technology can be operated in an integrated and continuous mode, is suitable for large-scale production of wires and thin strips, is high in machining efficiency and stable in performance batch, and meets the requirements for metal materials of high-end connectors in the fields of integrated circuits, new energy automobiles and the like.

The invention provides a gallium oxide single crystal dislocation characterization method based on mechanical exfoliation, which comprises the following steps: cutting a gallium oxide single crystal to obtain a polygonal single crystal sample; a tool with a sharp and hard surface is used for aligning the vertex angle of the single crystal sample, stripping is carried out along the gallium oxide cleavage surface, the mechanical stripping path is that the whole layer of surface extends towards the center along the vertex angle, and the whole layer of surface is completely stripped to obtain a clean and flat single crystal surface; carrying out surface activation pre-corrosion on the mechanically stripped single crystal; after ultrasonic cleaning, a sample is directly treated by a chemical corrosion method, and dislocation characterization of the gallium oxide single crystal is realized by analyzing the morphology and distribution of corrosion pits. The surface of the sample is processed by adopting a mechanical stripping method, a clean, flat and high-quality single crystal surface is obtained and is directly used for chemical corrosion method treatment to observe single crystal dislocation characteristics, multiple processing steps of the sample before chemical corrosion method treatment are simplified, and an efficient and feasible technical scheme is provided for gallium oxide single crystal dislocation characterization.

A method and device for a sensor using a graded wavelength configuring material. The wavelength configuring material can be configured for a selected wavelength using plurality of material regions of varying elemental concentrations in a continuous or step-wise pattern. The material compositions can include InP, InGaAs, GaAs, GaP, InGaAsP, InAs, InAlAs, InAlGaAs, InGaP, and the like. Further, the interface regions between adjacent material regions can be free from smearing of compositions. These material regions can also form a strained graded region overlying a buffer material and a silicon substrate. An array of photodetector materials can be formed overlying the wavelength configuring material. These materials can include an n-type material, an absorption material, a band transition material, and a p-type material, among others. The resulting device exhibits high performance at the selected wavelength and is characterized by low dislocation density.

The invention provides a preparation method of a copper target material, and belongs to the technical field of metal target material preparation. According to the preparation method of the copper target material, the copper blank is subjected to hot rolling, thick columnar crystals in an original as-cast structure of the copper blank are crushed into fine grains through hot rolling, and the grain structure is more uniform; and the total volume of gaps among crystal grains is rapidly reduced, an original loose structure is compacted into a compact structure, densification treatment of the copper blank is achieved, and the dislocation density of the copper blank is increased. And then the copper target blank is cooled to 25-40 DEG C and then is subjected to cold rolling, crystal grains in the copper target blank are further rearranged, gaps between the crystal grains are further compressed, the crystal grain structure of the copper target blank is more compact, and the dislocation density is further improved. And finally, a temperature stepped annealing process is adopted, so that internal stress generated in the hot rolling and cold rolling processes can be effectively eliminated, and the hardness of the copper target blank cannot be excessively reduced due to the annealing process.

The invention provides a preparation method of a high-quality gallium nitride film based on a porous silicon nitride insertion layer. The preparation method comprises the following steps: firstly, sequentially depositing a GaN low-temperature buffer layer and a u-GaN layer subjected to compression strain on a patterned sapphire substrate; a porous SiNx insertion layer is deposited on the u-GaN layer in situ, a nanoscale hole structure penetrating in the thickness direction is formed in the porous SiNx insertion layer, and the u-GaN layer is exposed at holes; then GaN nanorods vertically grow at the holes, finally, growth conditions are regulated and controlled to enable the GaN nanorods to transversely grow and combine to form a flat high-quality GaN thin film, and a gap is formed between the porous SiNx insertion layer and the GaN thin film. According to the method, the internal stress of the GaN film can be effectively reduced, the dislocation density is reduced, the film quality is improved, the process is simple, and the method is suitable for large-scale and low-cost industrial production of the GaN film.

The invention relates to the technical field of heat treatment of steel for high-performance heading machine tools, and discloses an ultra-fine grain solid-phase regulation and control process for improving the structure uniformity of alloy steel, which comprises the following steps: collecting electrical parameters of an induction loop and identifying sudden change of parameters of a phase change point to determine a phase change leading edge position; triggering pulse disturbance heating at a preset depth to generate transient volume dislocation stress, breaking core carbide segregation and driving stress extreme values to gather towards the center; controlling the temperature rise rate to make the nucleation rate higher than the diffusion rate so as to form a dispersed crystal nucleus; according to the method, the phase change transient volume dislocation strain field is used for blocking the continuity of the net-shaped hard and brittle phase, the structure heredity of the large-scale section steel is eliminated, the total cross-section structure is highly homogenized, equiaxed crystals are ultra-refined, and the intergranular fracture resistance of the material in the service environment is enhanced.

The invention provides a silicon nitride material and a preparation method thereof, and a structural member, the silicon nitride material comprises a silicon nitride crystal, and the average minor axis grain size of the silicon nitride crystal is less than or equal to 3.5 [mu] m. The silicon nitride material provided by the invention comprises the silicon nitride crystal, the average short-axis grain size of the silicon nitride crystal is smaller than or equal to 3.5 microns, and the grain size is small, so that concentrated stress can be effectively reduced, dislocation slippage can be retarded, defects and discontinuity at a grain boundary can be reduced, a phonon transmission path is optimized, and the service life of the material is prolonged. Therefore, the silicon nitride material has the characteristics of high hardness and high thermal conductivity.

The invention relates to the field of preparation of ultraviolet photoelectric detectors, in particular to a p-i-n type ultraviolet photoelectric detector based on a 4H-SiC-GaN heterostructure and a preparation method of the p-i-n type ultraviolet photoelectric detector based on the 4H-SiC-GaN heterostructure, the dislocation defect is greatly reduced on the material structure level, a foundation is built for subsequent high-quality crystal growth, it is ensured that the structure of the detector is stable under complex working conditions, and the performance of the detector is improved. Material damage caused by thermal expansion and cold contraction or lattice stress is effectively avoided, and the reliability and durability of the detector are greatly improved. And the preparation process is fine. The MOCVD technology is adopted for growth, and parameters of all links are accurately regulated and controlled. Furthermore, high-purity metal is matched with proper evaporation rate and deposition thickness, and is combined with a high-vacuum physical vapor deposition technology, so that good ohmic contact between the metal and a semiconductor is ensured, the hole injection efficiency is high, the carrier recombination probability is reduced, the photoelectric conversion efficiency is effectively improved, and the wide market prospect is achieved.

The invention discloses a method for growing a high-quality III-group nitride material by using a Si / SiC composite substrate, and belongs to the technical field of semiconductors. Different from a traditional method for growing SiC on a Si substrate, the Si / SiC composite substrate is formed through bonding, and the problems of high interface state density, mismatch dislocation and the like caused by growing SiC on the Si substrate can be avoided. The porous silicon layer prepared on the Si substrate provides non-complete tight coupling bonding, so that the stress in the bonding process can be released, and the warping of the composite substrate can be reduced. And meanwhile, the introduced SiC layer is beneficial to improving thermal conductivity and buffering stress, and the crystal quality of epitaxial nitride is improved by utilizing the excellent characteristic of high quality of PVD-AlN deposited on single crystal alpha-Al2O3, so that a high-quality III-group nitride material is obtained. According to the method for growing the high-quality III-group nitride material by effectively controlling stress and reducing mismatch dislocation, the performance and reliability of the device are improved.

The invention relates to an n-type silicon carbide single crystal and a growth method thereof, the growth method is a physical vapor transport method, a raw material area of a crucible is divided into a plurality of areas along the radius direction, and then SiC powder is sequentially filled into each area along the radius direction according to the particle size from small to large; and the partition plate arranged between the silicon carbide seed crystal and the SiC powder comprises a graphite plate and a metal carbide layer coated on the surface of the graphite plate, the partition plate is of a plane structure, the partition plate is provided with flow guide holes distributed in a concentric circle dot matrix manner, the distance between the adjacent flow guide holes is 2mm-20mm, and the vertical distance between the flow guide hole in the outermost layer and the edge of the partition plate is 2mm-20mm. By using the growth method provided by the invention, the large-size n-type silicon carbide single crystal with low crystal overall dislocation level, low resistivity and high uniformity can be obtained.

The invention discloses a method for detecting a dislocation slip line of a silicon single crystal, which is particularly suitable for detecting the dislocation slip line of the silicon single crystal with the diameter of more than 300mm and the doping agent of 1t of B element. 100 gt; and detecting the dislocation slip line of the crystal orientation silicon single crystal. The method comprises the following steps: prototype; 100 gt; after drawing of the crystal orientation silicon single crystal is completed, a sample with the thickness of 2-10 mm is cut out, and the sample is cleaned with deionized water; a mixed solution is used for corroding the sample, the sample is immersed into the mixed solution of nitric acid with the concentration being 65-68% and hydrofluoric acid with the concentration being 45-49%, the volume ratio of hydrofluoric acid to nitric acid in the mixed solution is HF: HNO3 = 10: 1, and the soaking time is 30-40 min; a visual inspection lamp is used for judging a corroded result, and the position and the length of a dislocation slip line are determined; and carrying out auxiliary judgment on the sample by using X-ray diffraction morphology. The detection method is simple and convenient to operate and easy to implement, chromium-free liquid corrosion is adopted, the position and the length of the dislocation slip line are determined under an accent light, interference factors can be eliminated, and the dislocation slip line can be accurately recognized.

The utility model provides a silicon carbide crystal growth device for improving the spiral dislocation defect. The silicon carbide crystal growth device comprises a crucible body and a plurality of graphite partition plates arranged in the crucible, and the graphite partition plates are arranged at the bottom of a raw material area of the crucible at equal intervals; the graphite clapboards are inserted into the silicon carbide powder at intervals, the heights of the graphite clapboards are in an arithmetic progression, so that the heights of the silicon carbide powder are also in an arithmetic progression, and the heights of the graphite clapboards and the silicon carbide powder in the corresponding areas are gradually reduced in the direction from the small surface area of the seed crystal to the direction far away from the small surface area. In the single crystal growth process, the silicon carbide powder in the graphite partition interlayer is heated to sublimate, and the distance between the surface of the silicon carbide powder and the growth surface of the seed crystal is reduced due to the height advantage of the silicon carbide powder in the graphite partition area with higher height, so that the growth component forms the component density advantage at the surface of the seed crystal in the area; the conversion and movement processes of screw dislocation in the crystal are effectively promoted, and the crystal quality 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 discloses a surface coating for prolonging the fatigue life of metal and a preparation method of the surface coating. According to the coating, face-centered cubic structure layers and hexagonal system structure layers are alternately stacked to form a superlattice structure, the total thickness ranges from 1.0 micrometer to 1.5 micrometers, and a base material is titanium alloy. The thickness of the face-centered cubic structure layer is 4-6 nm, the thickness of the hexagonal system structure layer is 1-3 nm, the Mohs hardness difference between the two layers is not larger than 2, and the average grain size is 1-2 nm. According to the coating, a stable high-toughness interface phase is obtained through a specific crystal structure and thickness regulation and control, and dislocation slippage and crack propagation are effectively prevented. A magnetron sputtering method is adopted for preparation, and the process comprises the steps of substrate surface pretreatment, bias cleaning and alternate deposition. The coating shows excellent anti-fatigue performance under the cyclic load condition, and the service life of the titanium alloy component can be remarkably prolonged.

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.

To stably obtain a nitride crystal substrate containing AlGaN. A production method for a nitride crystal substrate includes: (a) preparing a base substrate; (b) forming an intermediate layer including n-type group III nitride crystal, above the base substrate; (c) forming a cover layer on the intermediate layer, the cover layer including group III nitride crystal having a carrier concentration lower than a carrier concentration of the intermediate layer; (d) making the intermediate layer porous through dislocations in the cover layer by performing an electrochemical process, while maintaining a surface condition of the cover layer; (e) epitaxially growing a regrowth layer comprising group III nitride crystal, on the cover layer; and (f) peeling off the regrowth layer from the base substrate by using at least a portion of the intermediate layer made porous as a boundary, wherein in (e), crystal represented by a composition formula of AlxGa1-xN, where an Al composition ratio x is 0.05 or more and 0.8 or less, is grown as the regrowth layer.

The invention relates to a crucible structure for silicon carbide crystal growth, which structurally comprises a crucible, the crucible comprises an outer crucible and an inner crucible, the inner crucible is positioned at the inner bottom of the outer crucible, and a graphite ring and a graphite cover are sequentially arranged above the inner crucible. A hollow gap is formed between the outer side surface of the middle of the graphite ring and the outer crucible. A graphite heating body is arranged on the side face of the crucible in a surrounding mode, and the outer side of the whole of the crucible and the graphite heating body is wrapped with a heat preservation felt. The crucible has the advantages that the structural design is reasonable, and compared with a single-crucible structure in the prior art, the radial temperature gradient of the crystal can be effectively reduced, defects such as edge microtubes, carbon wrapping and dislocation can be reduced, the surface type of the silicon carbide crystal is improved, and the surface growth of the crystal is smoother.

The present invention relates to a method of producing an epitaxial wafer, the method comprising the steps of: forming a first layer on a growth substrate wafer; depositing a material layer on the first layer; and patterning the material layer to form a plurality of protrusions spaced apart from each other at predetermined intervals. According to the present invention, crystalline defects are hardly generated in regions having protrusions, and crystalline defects such as threading dislocations and the like are only generated on surfaces between the protrusions in conjunction with the growth of materials such as GaN, AlGaN, AlN, etc. Therefore, the crystallinity of epitaxial growth on a GaN-on-Si epitaxial wafer can be greatly improved. Accordingly, the performance and reliability of a HEMT power device and an LED optical device can be improved.

The invention discloses a patterned sapphire composite substrate and a preparation method, and relates to the field of LED epitaxial patterned substrate materials, and the patterned sapphire composite substrate comprises a substrate material layer which is made of sapphire, aluminum nitride or gallium nitride; a low refractive index layer material layer; the low-refractive-index material layer is attached to the periphery of the substrate material layer to form a conical inner and outer two-layer type composite pattern structure, and the density of the low-refractive-index material layer is in a gradient increase trend of 1.42-1.52 from a position close to the substrate to a position far away from the substrate. The method has the advantages that the light extraction efficiency is improved, the dislocation density is reduced, the crystal quality is enhanced, the etching process is optimized, the light extraction efficiency is improved, the process compatibility is high, and the cost effectiveness is high.

The invention discloses a surface etching method for revealing dislocation defects of tellurium indium lead single crystals, and relates to a method for revealing crystal defects. The invention aims to provide a surface etching method capable of accurately exposing crystal defects. The method comprises the following steps: firstly, carrying out directional cutting, multi-stage mechanical polishing and chemical mechanical polishing on a PIT single crystal to obtain a smooth and damage-free surface; and reacting iodine with concentrated nitric acid to generate iodic acid as a main oxidant, adding hydrofluoric acid for activation, diluting with an acetic acid-water mixed solution, and etching the crystal at a low temperature of 10 + / -1 DEG C under ultrasonic assistance. According to the method, the regular triangular conical etching pit can be formed on the PIT single crystal (001) surface, the depth is 100-300 nm, the pit bottom points to the [001] direction, and the dislocation defect is clearly revealed. The method has the advantages of clear etching morphology, high sensitivity, high reliability and simplicity and convenience in operation, and can be applied to the fields of PIT single crystal quality evaluation, defect analysis and growth process optimization.

The invention discloses a hot working quality intelligent prediction method based on establishment of coupling structure and deformation condition influences, and belongs to the field of metal material plastic forming processes. According to the method, the coupling influence of the microstructure state and the deformation condition is considered, the metal material hot working quality prediction method suitable for the actual machining process is established, and the problem that the hot working quality under the constant deformation condition and the non-constant deformation condition cannot be accurately predicted through an existing universal model is solved. According to the method, the dislocation density, the grain size, the dynamic recrystallization degree, the strain rate, the deformation temperature and the deformation degree serve as input variables, the power dissipation rate and the deformation instability factor serve as output variables, a BP neural network prediction structure is established, training is conducted according to the experimental result under the constant deformation condition, and the dynamic recrystallization degree is obtained. And a hot working quality intelligent prediction model influenced by the coupling tissue and the deformation condition is obtained. The prediction of the hot working quality of the metal material under the complex deformation condition in the single-pass thermal deformation process is realized, and the prediction accords with the actual engineering processing condition.

The invention discloses a method and device for preparing a mixed crystal structure material through friction stir solid-phase deposition, and belongs to the technical field of heterostructure material preparation. According to the method, firstly, a deposition head is used for carrying out single-layer friction stir solid-phase deposition on a needed material, then a special corrugated roller is used for carrying out cold rolling to enable different positions of the surface of the deposition material to be subjected to different degrees of cold deformation, and therefore uneven high dislocation density is introduced into a deposition layer, and then next-layer friction stir solid-phase deposition is carried out on the surface of the deposition layer. In the friction-stir solid-phase deposition process, static recrystallization and static recovery rapidly occur in a local high-dislocation-density area to maintain fine grains, and grain growth rapidly occurs in a low-dislocation-density area due to heating, so that the whole deposition layer shows the mixed crystal structure characteristic that fine grains and coarse grains coexist; the block mixed crystal structure material can be prepared through stirring friction solid phase deposition and cold rolling circulation.

The invention relates to the technical field of metal material performance detection, and discloses a method for detecting ductile-brittle transition temperature of a metal material based on a thermal method. The method comprises the following steps: acquiring the average grain size of a material through three-dimensional characterization, quantitatively estimating the movable dislocation density generated by grain boundary thermal activation emission at a specific temperature in combination with a preset dislocation emission coefficient, and linearly superposing the movable dislocation density with the inherent pre-stored movable dislocation density of the material to obtain a total movable dislocation density estimated value. And comparing the total movable dislocation density calculated at different temperatures with the ductile-brittle transition critical threshold obtained from the material knowledge base to determine the critical temperature meeting the condition, namely the ductile-brittle transition temperature. According to the method, the mechanical prediction of the ductile-brittle transition temperature is realized by quantifying the contribution of a key dislocation source from a plastic deformation microphysical mechanism, and the dependence of a traditional method on a large number of destructive experiments is reduced.

The application provides a group III nitride structure and a manufacturing method thereof. In the manufacturing method, a first mask layer is used as a mask to etch a first group III nitride epitaxial layer to form a groove; a second mask layer is formed on at least the bottom wall of the groove, and the first group III nitride epitaxial layer is subjected to first epitaxial growth with the second mask layer as a mask to form a second group III nitride epitaxial layer which fills the groove and grows in a horizontal direction; and then the second group III nitride epitaxial layer is subjected to second epitaxial growth to form a third group III nitride epitaxial layer on the second group III nitride epitaxial layer and the first mask layer. Since the dislocations of the first group III nitride epitaxial layer mainly extend in the thickness direction, the first epitaxial growth which grows in a horizontal direction can block the dislocations from extending upwards, thereby significantly reducing the dislocation density of the second group III nitride epitaxial layer and the third group III nitride epitaxial layer.