34 results about "Stress induced martensite" patented technology

An electrosurgical apparatus for coagulating tissue includes an elongated flexible tube having a proximal end, a distal end and a source for supplying pressurized ionizable gas to the proximal end of the tube. The apparatus also includes a hollow sleeve made from a shape memory alloy having a generally curved austenite state and displaying stress-induced martensite behavior. The hollow sleeve is restrained in a deformed stress-induced martensite configuration within the tube and partial extension of a portion of the hollow sleeve from the tube transforms the portion of the sleeve from the deformed configuration to the generally curved austenite configuration such that the gas is directed transversely at the tissue. An electrode ionizes the gas in the region between the sleeve and the tissue. Other embodiments of the present disclosure also include a wire connected to the distal end of the tube which movable from a first postion wherein the tube is disposed in a generally rectilinear, parallel fashion relative to the tissue to a second retracted position wherein the distal end of the tube flexes at an angle to direct the gas towards the tissue. Still other embodiments of the present disclosure include a corona electrode for inducing ignition of the gas.

A process for assembling a medical device made from a nickel-titanium alloy for use in a mammalian body while avoiding the formation of stress-induced martensite and a medical device used in combination with a delivery system for deployment into the mammalian body are disclosed. By heating the nickel-titanium alloy of the medical device to a temperature above Md, and deforming and installing the device into a delivery system or holding capsule, it is possible to avoid the formation of stress-induced martensite in the stent, which stays in the austenitic phase throughout.

An electrosurgical apparatus for coagulating tissue includes an elongated flexible tube having a proximal end, a distal end and a source for supplying pressurized ionizable gas to the proximal end of the tube. The apparatus also includes a hollow sleeve made from a shape memory alloy having a generally curved austenite state and displaying stress-induced martensite behavior. The hollow sleeve is restrained in a deformed stress-induced martensite configuration within the tube and partial extension of a portion of the hollow sleeve from the tube transforms the portion of the sleeve from the deformed configuration to the generally curved austenite configuration such that the gas is directed transversely at the tissue. An electrode ionizes the gas in the region between the sleeve and the tissue. Other embodiments of the present disclosure also include a wire connected to the distal end of the tube which movable from a first postion wherein the tube is disposed in a generally rectilinear, parallel fashion relative to the tissue to a second retracted position wherein the distal end of the tube flexes at an angle to direct the gas towards the tissue. Still other embodiments of the present disclosure include a corona electrode for inducing ignition of the gas.

A process for assembling a medical device made from a nickel-titanium alloy for use in a mammalian body while avoiding the formation of stress-induced martensite and a medical device used in combination with a delivery system for deployment into the mammalian body are disclosed. By heating the nickel-titanium alloy of the medical device to a temperature above Md, and deforming and installing the device into a delivery system or holding capsule, it is possible to avoid the formation of stress-induced martensite in the stent, which stays in the austenitic phase throughout.

A method to limit or exclude operational creep of the bolts and gaskets of Bolted Flanged Connections (BFCs) is disclosed. The method consists in the use of bolts and gaskets manufactured from the same Shape Memory Alloys (SMAs) having temperature intervals of reverse martensitic phase transformation close to operational temperatures of the BFCs. These bolts and gaskets of the BFCs are shape-memorized to the compression (bolts) and “swelling” (gaskets) during (1) the formation of stress-induced martensite under temperature of martensite state of the SMAs while bolt preload application, or (2) during the formation of stress-induced martensite while loading-unloading previously stretched bolts and previously compressed gaskets under temperature of martensite state resulting in residual bolt elongations and residual gasket contraction followed by bolt preload application. Constrained shape recovery of initial length of the bolts and initial thickness of the gaskets under operational temperatures of the BFCs is accompanying by appearance of reactive shape-recovering stresses having direction inverse to the direction of operational creep of the bolts and gaskets that limits or excludes their operational creep.

The invention discloses a method for representing recovery characteristics of a Fe-Mn-Si-based memory alloy by in-situ X-ray diffraction. In the method, in-situ X-ray diffraction analysis is introduced to the inverse phase change process of the Fe-Mn-Si-based memory alloy, thus phase change characteristics of conversion from martensite to austenite under stress induction in the heating shape recovery process of the Fe-Mn-Si-based memory alloy can be represented synchronously in real time through high-temperature in-situ X-ray diffraction. The method mainly comprises the steps of: pretreating a sample and carrying out X-ray diffraction on the pretreated sample by utilizing a high-temperature in-situ sample platform so as to obtain an in-situ X-ray diffractogram representing the shape memory recovery characteristics of the Fe-Mn-Si-based memory alloy. By using the method disclosed by the invention, phase change characteristics of the Fe-Mn-Si-based memory alloy can be presented from a macroscopic perspective, and the change of structure in the recovery process is synchronously, in situ and visually researched through diffraction pattern analysis.

The invention discloses a method for manufacturing shear-type phase change crack resistance by laser additive manufacturing, which includes adopting laser additive manufacturing technology, and using high-entropy alloy powder with FCC→HCP martensitic phase transition as a special powder for additive manufacturing; Dry the metal powder in a vacuum drying oven for 12 hours at a drying temperature of 120°C; perform additive manufacturing printing on the dried high-entropy alloy powder, and the printing parameters are: laser power 400W; scanning speed 800-1600mm / s ; The scanning distance is 0.09mm; the powder coating thickness is 0.03mm; the substrate preheating temperature is 100°C. The invention solves the problem of metallurgical defects such as thermal crack deformation caused by high temperature and high stress gradient in the molten pool in the traditional laser additive manufacturing process. And on the basis of this research, the idea of ​​stress-induced martensitic transformation to suppress hot cracks in additive manufacturing alloys is extended to other additive manufacturing alloy systems, providing a new method for additive manufacturing of crack-free alloys.

The invention discloses a design manufacturing method and an application method for laser cladding powder. The design manufacturing method includes preparing Fe-Mn-Si memory alloy powder and putting the memory alloy powder into a ball grinder to process powder mixing. The application method includes processing a vacuum drying treatment before the cladding, presetting the cladding powder on base materials, and processing the cladding with laser which is 1.5-3 Kw in laser power, 400-1000 mm / min in scanning speed and 3 mm in laser diameter. By the stress of the laser cladding layer of the Fe-Mn-Si memory alloy, martensitic transformation and the martensitic deformation compatibility are induced so as to effectively remove the residual stress of the cladding layer and improve the fatigue strength of the cladding layer with no need of adding extra processing. The laser cladding powder of the iron-base alloy has the advantages of being simple in preparation technology, applicable to mass production, good in wear resistance, low in residual stress, high in fatigue strength, and the like.

The invention relates to a shape memory alloy blocking nut and its preparing process. The raw materials for the nut comprise the following components(in % by weight): C 0.01-0.05, Mn 15.0-17.0, Si 4.8-5.2, Cr8.5-9.5, Ni 6.5-7.5, P 0.01-0.03, S 0.01-0.02, N 0.03-0.05, and Fe 60.65-65.05. The preparing process comprises: (1) preparing the raw materials and rolling to obtain the iron-base shape memory alloy rod stocks with outside hexagon strip and inner circular hole; (2) solution treatment for the rod stocks: keeping the temperature of 950K. to 1150K. for 30 min to 60 min; (3) shape memory training for the rod stocks; (4) cutting the rod stocks to nut blanks, and processing the inner circular hole according to the given size of 94% to 96%; (5) reaming the nut to given size for completing the stress induced martensitic transformation of the nut; (6) fine machining for the internal thread; (7) pre-tightening the nut according to the estimated force moment, keeping the temperature of 500K to 800K for 15min to 45min, and carrying out the annealing treatment.

The invention relates to the technical field of biomedical shape-memory composite materials, in particular to a Nb-coated NiTi shape-memory composite material and a preparation method thereof. The composite material prepared by this method has good biocompatibility, high stress-induced martensitic transformation critical stress and large recoverable strain, which is expected to solve the existing single biomedical shape memory alloy, such as NiTi Base alloys and Ni-free β-titanium alloys cannot have good biocompatibility, high stress-induced martensitic transformation critical stress and large recoverable strain at the same time, and are expected to be obtained in the biomedical field application.