41 results about "Grain boundary migration" patented technology

Al-Mg-Er-Zr heat-resistant aluminum alloy and its preparation technology belong to the technical field of alloy. The alloy is obtained by adding 1.1-5.1 wt% of Mg, 0.25-0.35 wt% of Er and 0.25-0.3 wt% of Zr into an aluminium matrix. The percentage is weight percentage of each component in the Al-Mg-Er-Zr heat-resistant aluminum alloy. The preparation technology comprises the following steps: smelting Al-Mg-Er-Zr alloy at 760-780 DEG C, stirring after each alloy element is smelted, casting to obtain as-cast alloy, isochronally annealing the alloy every 25 DEG C between 150-475 DEG C for 3 hours, and carrying out cold rolling on the annealed alloy by a cold-rolling mill. Total deformation of cold rolling is 60-80%. A lot of Al3 (Er,Zr) strengthening phase particles are separated out, and the hardening effect is remarkable during the annealing process. When an alloy cold-rolled sheet is used at high temperature, the strengthening phase particles can impede alloy dislocation and grain and sub-grain boundary migration and merging and inhibit recrystallization process of the alloy. Recrystallization temperature of the alloy is raised.

The invention discloses a method for rapidly sintering fully stabilized zirconia powder under low temperature and normal pressure, which belongs to the field of fine chemical engineering. The method includes the steps of zirconium salt and stabilizer mixing, coprecipitation, washing, drying, heat treatment, mixing with molten salt solution, drying, grinding, dry pressing, calcination and the like. By introducing trace molten salt into the fully stabilized zirconia powder and utilizing the molten salt to form liquid phase under low temperature, while promoting the grain boundary diffusion of the powder, the method inhibits the grain boundary migration of the powder, consequently, the contradiction between densification and grain coarsening in the process of sintering the fully stabilized zirconia powder is solved, and the normal-pressure rapid sintering of the fully stabilized zirconia powder under low temperature is realized; in addition, cations in the molten salt get into the ZrO2 crystal lattice by doping, consequently, the ZrO2 crystal form is further stabilized, and the properties of the material are further improved; the average bending strength of the obtained sintered body is greater than 450Mpa, the theoretical density is greater than 93 percent, and the grain size is between 425nm and 520nm.

The invention provides CuAlMn shape memory alloy and a preparation method thereof. The alloy is prepared from the following component by mass percentage: 12.0-20.0% of Al, 7.0-15.0% of Mn and the balance of Cu; the preparation method of the alloy comprises the following steps: (1) selecting Cu, Al and Mn and proportioning according to the alloy composition, and then smelting in a crucible to obtain an alloy ingot; (2) deforming the alloy ingot to obtain a sample to be used; (3) enabling the sample to be used to be subjected to regional heating, arranging a temperature field having a temperature gradient near a heating region, and enabling the sample to be subjected to directional annealing after passing through the heating region and the temperature field; (4) then, adopting a cyclic heattreatment method, an orientation annealing method or a cyclic heat treatment and orientation annealing combined method to obtain the CuAlMn shape memory alloy having a single crystal or a columnar crystal structure. The method provided by the invention uses the directional annealing to realize directional grain boundary migration of the CuAlMn shape memory alloy in an abnormal grain growth process, thus being beneficial to the directional growth of crystals; the method is simple in directional annealing process, is not limited by the sizes and shapes of products, and can be used for efficiently preparing the large-size single-crystal CuAlMn shape memory alloy.

The invention discloses a welding material and a production device thereof, and relates to the technical field of welding materials; in order to solve the problem of high-temperature plastic loss cracks; it specifically includes a base, the outer wall of the top side of the base is provided with a mounting groove, and one of the mounting grooves is The side inner wall is fixed with the first motor through the support plate, the output end of the first motor is fixed with the worm through the coupling, and the two ends of the worm are respectively fixed with the top of the base through the bearing seat, and the outer wall of the top circle center of the base is fixed with the support shaft There are driving teeth, and the driving teeth and the worm mesh with each other. The outer wall on one side of the base is fixed with the first mounting seat and the second mounting seat by bolts, and the second motor is fixed on the outer wall of the second mounting seat through a support plate. The driving gear The top outer wall is screwed with a mounting plate. The invention can block the accumulation of lattice defects, prevent grain boundary sliding and grain boundary migration from occurring and meeting at the same time, thereby avoiding the formation of high-temperature plastic loss cracks.

The invention provides an in-situ synthesis of aluminum carbide-reinforced aluminum-based composite material and a preparation method thereof, comprising aluminum powder and graphene powder, wherein the aluminum powder and graphene powder generate dispersedly distributed Al with nanoscale through in-situ reaction 4 C 3 , nanoscale Al 4 C 3 It is distributed in the composite material in two forms, one of which is that the two ends of the rod-shaped shape grow into the two aluminum grains respectively, pinning two adjacent aluminum grains, and the other is that the two ends of the rod-shaped shape grow along the crystal grains. Boundary arrangement can effectively prevent dislocation and grain boundary migration. In one aspect of the present invention, nanoscale Al 4 C 3 Effectively pin the grain boundary migration of the Al matrix, retain the strength of the Al matrix, and at the same time, Al 4 C 3 As a hard reinforcing phase, the composite material has high room temperature strength and high-temperature mechanical properties due to the stress bearing and Orowan effect, and the composite material has broad application prospects in the fields of aerospace and other high-service temperature conditions.

The invention discloses a molding method for realizing secondary sintering preparation of a high-toughness three-dimensional nano ceramic artificial bone by utilizing a selective laser and a temperature control furnace. In the first sintering, the selective laser is utilized for layer-by-layer scanning of a biological ceramic powder according to artificial bone model information, and layers are superposed to obtain a nano artificial bone initial green body having a complex geometric profile and controllable interconnected micropores; and in the second sintering, the laser molded piece is subjected to long-time heat preservation at a relatively low sintering temperature in the temperature control furnace, grain boundary migration is inhibited in the heat preservation stage, grain boundary diffusion is maintained, thus grain growth is under control, and a densification process can be still carried out until the artificial bone is fully densified. The molded artificial bone not only has the profile consistent with an implantation site and has the interconnected and controllable pore space structure, but also is a nano biological ceramic artificial bone scaffold having good mechanical properties.

The invention discloses a technology for increasing the volume density of tabular corundum. The technology comprises the steps that gamma-aluminum oxide and lanthanum oxide are mixed and ground, and ground powder is put into a ball forming machine, subjected to ball forming, dried and sintered to obtain tabular corundum, wherein the mass fraction of lanthanum oxide in the ground powder is 0.01-0.05%. According to the technology for increasing the volume density of tabular corundum, aiming at the characteristic that grain boundary migration influences crystal growth in solid-phase sintering inthe production process of tabular corundum, a small amount of lanthanum oxide is added to fine powder to improve the grain boundary characteristic, so that the aim of promoting sintering is achieved,the sintered product is high in volume density and good in crystal development, the liquid phase does not exist, and the sintering technology is easy to control.