33 results about "Intergranular fracture" patented technology

Pressureless sintering of silicon carbide with fracture toughness in excess of about 4 MPa-m1 / 2 as measured by the single-edge precracked beam (SEPB) technique while maintaining a density greater than 3.1 g / cc for compositions with SiC greater than about 94 wt. % is made possible through the use of metallic Al to promote sintering and grain growth. Boron and carbon may be used as traditional sintering aids, with nitrogen to suppress grain growth, and additions of yttrium and / or lanthanide elements to promote intergranular fracture.

Provided is a solid electrolyte material provided which, while maintaining a high oxygen ion conductivity, minimizes the extraction of scandia caused by impurities such as silicon in the fuel gas, and has improved intergranular strength in order to eliminate intergranular fracture caused by crystalline modification. The solid electrolyte material is a zirconia solid electrolyte material having yttria dissolved therein, has cubic crystals as the main ingredient, and is further characterized by having a lanthanoid oxide dissolved therein.

The invention provides a Fe-Mn-Al-Ni-Cu superelastic alloy and a preparation method thereof, comprising 25-40% of Mn, 10-20% of Al, 1-15% of Ni, 1- 10% of Cu, the rest is Fe; prepared by the following steps: (1) batching according to atomic percentage content, fully smelting and mixing in vacuum or inert gas protection to obtain castings; (2) castings obtained in step (1) Homogenizing treatment, and then deforming to obtain the desired sample alloy; (3) Selecting the directional annealing process and / or the cyclic heat treatment process as required to control the grain size. The invention can effectively improve the single crystal preparation efficiency of cyclic heat treatment and directional annealing, improve the grain growth rate of the alloy, and avoid the tendency of intergranular fracture caused by conventional abnormal grain growth promoting elements Ti and Al in FeMnAlNi alloy.

The invention provides a heat treatment process for reducing the ductile-brittle transition temperature and the intergranular fracture ratio of turbine blades, which can effectively avoid the problem that the process effect is easily affected by the chemical composition of blade raw materials when the existing sub-temperature annealing process is used to treat turbine blades , and can solve the problem of high ductile-brittle transition temperature and intergranular fracture ratio of the blade caused by the blade staying at high temperature for too long in the existing sub-temperature annealing process. Put the blades evenly into the general quenching basket according to the process plan, and then put the quenching basket into the heat treatment quenching furnace, which is characterized in that: the blades are quenched twice in the quenching furnace, and the first quenching temperature is 980℃~1070℃, heat preservation for 1 hour to 3 hours, cooling rate 20℃ / minute~50℃ / minute, the second quenching temperature is 900℃~1000℃, heat preservation for 15 minutes~120 minutes, cooling rate 30℃ / minute ~50°C / min, and ensure that the first quenching temperature is 20°C to 100°C higher than the second quenching temperature.

The invention provides a method for preparing neodymium iron boron magnetic powder for a sintered magnet, and belongs to the field of magnetic materials. The method includes the followingprocesses that neodymium iron boron powder particles are prepared by adopting a gas atomization method, crystalline grains inside the powder particles grow to 1-3 microns by vacuum heat treatment, the intergranular fracture of the powder particles occurs after hydrogen decomposing, and single crystal particles with a particle size of 1 to 3 microns are finally obtained after dehydrogenation. The method has theadvantages that the neodymium-rich phase of the neodymium iron boron particles prepared by the gas atomization method is evenly distributed at the boundary ofNd2Fe14B main phase crystalline grains, and the neodymium-rich phase uniformly covers the surface of the Nd2Fe14B main phase crystalline grains in the form of a thin layer by means of hydrogen absorption intergranular fracture, so that the neodymium-rich phase in the finally prepared sinteredneodymium iron boronmagnetuniformly covers the periphery of the Nd2Fe14B main phase crystalline grains in the form of a thin layer, demagnetizationexchange coupling is greatly enhanced, neodymium iron boroncrystalline grains prepared by the method are fine and uniform, and the magnetic properties of the obtained neodymium iron boron magnet, particularly the coercive force, are high after orientation molding, sintering and tempering treatment areconducted on the neodymium iron boron magnetic powder prepared by the method.

The invention provides a method for obtaining an intergranular fracture from austenite steel and application of the method. According to the method, after the surface of an austenite steel sample is electrolytic-polished, the austenite steel sample is subjected to cathodic hydrogen charging; then the two ends of the austenite steel sample are clamped for a while, and the austenite steel sample is put into a surface analyzing device; under the vacuum environment, the preset fracture of the austenite steel sample is primarily pressed for many times, then the preset fracture of the austenite steel sample is pressed to be broken at a time, and the intergranular fracture is obtained. The method is simple in technique and short in time consumption; operation steps are simple and controllable and easy to achieve; and the austenite steel fracture obtained through the method is a typical intergranular fracture, pollution can be effectively avoided, objective and accurate evidences can be provided for component analysis of a grain boundary, and the intergranular fracture is applicable to component analysis of the grain boundary of austenite steel.

The method for detecting austenite grain size of spring steel includes the following process steps: (1) Sampling: take a spring steel wire rod sample with a length of 150~200mm; (2) Heat treatment: heat the sample in an environment of 860±10°C and keep the temperature After 55~65min, put it into fast-flowing water for quenching to obtain a complete martensite structure; (3) Sample preparation: cut a 1~2mm deep crack in the middle of the heat-treated sample, soak it with dilute sulfuric acid solution After 24~30 hours of passing cotton wrapped in the crack, the sample is knocked off along the crack to form a fracture; (4) Detection: observe the fracture with a scanning electron microscope, identify the grain boundary, and use the straight line intercept method to determine the grain. Spend. In the present invention, the directly quenched sample is prepared by the fracture method and then infiltrated with hydrogen to form the intergranular fracture section, the intergranular morphology is observed by scanning electron microscope, and the grain size information is obtained by software and the intercept method.

The invention relates to a tensile fracture determining method for a crack forming period of a steel and iron material, which belongs to the technical field of failure analysis of a steel and iron material. The method comprises the following steps: firstly preparing a tensile sample comprising cracks, performing the breaking test, separating two crack surfaces, and determining the crack forming period according to characteristics of the existence of dimples of a micro-morphology of a fracture, cleavage, quasi-cleavage or intergranular fracture and the like. The method has the advantages that compared with the existing metallographic observation method, the tensile fracture analysis method does not damage the morphology of the crack and micro-tissues nearby the crack, so that the determination accuracy of the crack forming period can be improved, and the important evidence can be provided for analyzing the forming reason of the crack and making the preventive measures.

The invention provides a heat treatment method for manufacturing a high-strength titanium alloy by electric arc additive manufacturing and a reinforced high-strength titanium alloy, which belong to the field of titanium alloys. In the present invention, after the first heat treatment is performed on the high-strength titanium alloy manufactured by arc additive material, the first cooling is performed to the temperature of the second heat treatment, and the second heat treatment is performed; then the second cooling is performed to room temperature, and then the temperature is raised to the temperature of the third heat treatment to perform the third heat treatment. ; The temperature of the first heat treatment is 10-30°C above the β-transition point of the high-strength titanium alloy produced by arc-added materials, and the time is 15-30 minutes; the temperature of the second heat-treatment is below the β-transition point of the high-strength titanium alloy produced by arc-added materials 40-75°C, the time is 1h; the temperature of the third heat treatment is 500-550°C, and the time is 4-6h. The high-strength titanium alloy treated by the heat treatment method provided by the invention produces a "feather-like" grain boundary α phase at the grain boundary, which prevents intergranular fracture during stretching and can remove residual stress in the titanium alloy.