9 results about "Basal plane" patented technology

The present application belongs to the field of light metal plastic forming, and particularly relates to a device and method for preparing fine-grained magnesium alloy rod by asymmetric multi-directional shear extrusion. The wedge block combination in the present application can combine multi-directional shear extrusion deformation and differential speed torsional deformation, effectively weaken the magnesium alloy basal plane texture, and improve the mechanical properties of the magnesium alloy. While the magnesium alloy material is subjected to torsional extrusion in the torsional extrusion deformation zone, the sectional area of the channel gradually decreases, and the angle of the channel deflection is different, so that the frictional force of the magnesium alloy material on the surface of the convex and concave dies at the contact position is different, and the degree of torsional deformation is also different, so that the material realizes differential speed torsional deformation, and the grain refinement effect of the magnesium alloy rod is more remarkable. When the magnesium alloy material passes through the large and small concave dies, the deformation degrees of the magnesium alloy material are different due to the particularity of the structure, so that the grain refinement is effectively realized. At the same time, the flowability of the magnesium alloy material is also different, causing differential speed flow to deflect the c-axis, thereby weakening the texture.

Provided are a method for manufacturing a silicon carbide single crystal, and a silicon carbide single crystal ingot which ensure a high crystal growth rate and increase the ratio of conversion from basal plane dislocations to threading edge dislocations. The method prepares a seed substrate composed of silicon carbide having an off-angle in a [1-100] direction with respect to a {0001} plane; and grows a silicon carbide single crystal layer on the seed substrate by an HTCVD method, thereby converting basal plane dislocations contained in the seed substrate to threading edge dislocations during crystal growth.

The application discloses a titanium alloy extruded pipe blank with gradient texture and a preparation method thereof. The titanium alloy extruded pipe blank with gradient texture has gradient texture characteristics in the wall thickness direction, including a surface layer region: within a depth range of 0-1.5 μm from an outer surface and / or an inner surface, a {0001} basal plane strong shear texture is formed, and the crystallographic orientation of the region has an included angle of 30°-60° with the radial direction; a core region: a wall thickness center region, the texture strength is weak, and the texture strength is randomly distributed or weak; a transition region: between the surface layer region and the core region, the texture strength changes in a gradient manner; and a maximum pole density difference of the surface layer and the core region is greater than or equal to 4. Through the gradient texture design, the surface layer of the pipe blank forms a strong shear texture, has high crack resistance, the core region keeps random texture, and provides isotropic high plastic deformation capacity. The performance zoning enables the pipe to withstand a larger deformation amount without being prone to cracking in the subsequent cold working process.

The invention discloses an in-plane texture heterogeneous magnesium alloy and a preparation method thereof. The preparation method of the in-plane texture isomeric magnesium alloy comprises the following steps: (1) preparing a basal plane texture magnesium alloy plate; and (2) rolling the base texture magnesium alloy plate in the step (1) by using a roller-shaped rolling die to obtain the base texture magnesium alloy plate with the deformation of 3-8%, a main body of the roller-shaped rolling die is a roller, and a plurality of protrusions (2) which are evenly distributed in an array mode are arranged on the outer surface of a roller body (1) of the roller. According to the method, multi-pass deformation, complex intermediate / subsequent annealing and expensive special equipment are omitted, the process is extremely simple, the cost is extremely low, the huge potential of large-scale and low-cost industrial production is achieved, and the problems that in the prior art, the process is complex, the cost is high and the efficiency is low are solved.

A method of preventing basal plane dislocations (BPDs) from expanding from a SiC substrate or a highly doped buffer layer into an epitaxial device / active layer comprising the steps of providing a substrate, etching the substrate, converting BPDs to electrically benign threading edge dislocations, growing a first buffer layer on the substrate, creating a growth interrupt layer or second etch layer, growing a second buffer layer, growing a drift layer, and preventing BPDs from expanding into the drift layer. A device capable of preventing basal plane dislocations (BPDs) from expanding from a SiC substrate or a highly doped buffer layer into an epitaxial device / active layer comprising a substrate, a first buffer layer, a growth interrupt layer or etch layer, a second buffer layer and a drift layer. The drift layer carrier lifetime is not reduced. BPD expansion is prevented at current densities up to 12 kA / cm2.

The application discloses a method for regulating magnesium alloy basal precipitates, and belongs to the technical field of magnesium alloys. The method comprises the following steps: melting and casting raw materials according to a preset Mg-Gd-Y-Zn-Mn alloy composition and content, and then performing rapid solidification and artificial aging treatment; the Mg-Gd-Y-Zn-Mn alloy comprises 8.67%-8.89% of Gd, 3.85%-3.95% of Y, 3.28%-6.47% of Zn and 0.96%-1.96% of Mn in terms of mass percentage, and the balance is magnesium and inevitable impurities; and (Gd+Y):Zn=1:1 or 2:1 in terms of atomic percentage. According to the above method, high-density gamma'' basal precipitates are maintained during peak aging and overaging, and the process window for forming high-density distributed gamma'' basal precipitates in the Mg-Gd-Y-Zn-Mn alloy is effectively increased.

Provided is a method capable of simultaneously producing multiple sheets of an SiC single crystal substrate having a small amount of warpage, a low basal plane dislocation density, and a large crystal growth thickness. This method involves: a step for preparing a plurality of containers; a step for arranging, in each of the containers, an SiC single crystal as a seed crystal and SiC powder mixture containing SiC powder and a liquid phase generation aid so as to form an SiC powder mixture layer in which the SiC powder mixture is in contact with at least one plane of the SiC single crystal, wherein the liquid phase generation aid contains an oxide; a step for arranging the containers so as to be aligned with each other in the horizontal direction and / or the vertical direction in a firing furnace; and a step for heating the inside of the firing furnace so as to form a temperature gradient in which the temperature is increased or decreased from an upper portion toward a lower portion to subject the containers containing the seed crystal and the SiC powder mixture to heat treatment at an average furnace temperature of 2240-2560°C, thereby growing the SiC single crystal on the seed crystal.

Provided is a method for manufacturing a silicon carbide substrate 100 that has a substrate layer 101 and an epitaxial layer 102, the method comprising: a detection step for detecting a basal plane dislocation (BPD) present in the epitaxial layer 102 by irradiating the silicon carbide substrate 100 with inspection light L1; an expansion step for irradiating the area in which the basal plane dislocation (BPD) detected in the detection step is present with expansion light L3 for expanding a Shockley type stacking fault (SSF) from the basal plane dislocation (BPD); and a contraction step for irradiating the Shockley type stacking fault (SSF) expanded from the basal plane dislocation (BPD) in the expansion step with contraction light L4 for contracting the Shockley type stacking fault (SSF). In cases where a plurality of basal plane dislocations (BPD) are detected in the detection step, in the expansion step, after irradiating one region in which a basal plane dislocation (BPD) is present with expansion light, another region in which a basal plane dislocation (BPD) is present is irradiated with expansion light L3 concurrently with the contraction step, and this operation is repeated for all regions in which a basal plane dislocation (BPD) is present.

The invention provides a method and a system for predicting influence of basal plane dislocation on material performance, which are applied to the technical field of material science, and the method comprises the following steps: obtaining input characteristics of a to-be-predicted material, the input characteristics of the to-be-predicted material at least comprising basal plane dislocation density, basal plane dislocation type, doping rate, temperature and external field intensity; inputting the input features of the to-be-predicted material into a performance influence prediction model for performance prediction to obtain a performance prediction value of the to-be-predicted material; the performance influence prediction model is obtained by training based on the first data set and the trained machine learning potential model. According to the scheme, the performance influence prediction model is obtained through training of the first data set and the trained machine learning potential model, and then the performance prediction value of the to-be-predicted material is obtained through prediction of the performance influence prediction model. The machine learning potential model covers the association between the long-term evolution of the basal plane dislocation and the performance of the large-size material, so that the prediction effect of the association between the basal plane dislocation and the performance of the material is improved.