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 issue. 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 position 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.

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 discloses maraging stainless steel and a preparation method thereof. The maraging stainless steel comprises 9.0-13.0 wt% of Cr, 11.0-15.0 wt% of Ni, 1.5-4.0 wt% of Mo, no more than 2.5 wt% of Cu, 1.2-1.9 wt% of Ti, no more than 2.0 wt% of Mn, no more than 2.0 wt% of Al, no more than 1.0 wt% of Si, less than 0.03 wt% of C, and the balance Fe. When an alloy is subjected to complete austenitizing and rapidly cooled to the room temperature, the alloy is in a supercooled austenite state, the material is in stress-induced martensite phase transformation to be transformed into a martensite state during cold machining, and the Vickers hardness increment Hv can reach 250-300 after aging treatment is conducted. The stainless steel is especially suitable for manufacturing small-sectional-area products like fishing hooks and medical suture needles.

A medical device for use within a body lumen that is made from a binary nickel-titanium alloy that remains in its austenitic phase throughout its operational range is disclosed. The medical device, such as an intraluminal stent, is made from superelastic nickel-titanium and may optionally be alloyed with a ternary element. By adding the ternary element and/or through heat treatment, it is possible to lower the phase transformation temperature between the austenitic phase and the martensitic phase of the nickel-titanium alloy. By lowering the phase transformation temperature, the martensite deformation temperature is likewise depressed. It is possible then to depress the martensite deformation temperature below body temperature such that when the device is used in a body lumen for medical treatment, the nickel-titanium device remains completely in the austenitic phase without appearance of stress-induced martensite even if the device is placed under stress.

Cold worked nickel-titanium alloys that have linear pseudoelastic behavior without a phase transformation or onset of stress-induced martensite as applied to a medical device having a strut formed body deployed from a sheath. In one application, an embolic protection device that employs a linear pseudoelastic nitinol self-expanding strut assembly with a small profile delivery system for use with interventional procedures. The expandable strut assembly is covered with a filter element and both are compressed into a restraining sheath for delivery to a deployment site downstream and distal to an interventional procedure. Once at the desired site, the restraining sheath is retracted to deploy the embolic protection device, which captures flowing emboli generated during the interventional procedure. Linear pseudoelastic nitinol is used in the medical device as distinct from non-linear pseudoelastic (i.e., superelastic) nitinol.

The invention relates to a method for improving the function stability of a nickel-titanium shape memory alloy, and belongs to the field of nickel-titanium shape memory alloys. According to the method, dislocations and other defects are introduced into the nickel-titanium shape memory alloy, the dislocations serve as activity position points for promoting second phase nucleation, then, fine and evenly-distributed nano reinforcement phases are formed in a matrix structure of the nickel-titanium shape memory alloy through later aging treatment, accordingly, the matrix strength of the nickel-titanium shape memory alloy is obviously improved, and then the function stability of the alloy is improved. Meanwhile, in the method, only temperature martensite phase change induction circulation or stress martensite phase change induction circulation need to be conducted on a nickel-titanium shape memory alloy component before aging treatment, and operation is simple and convenient; and the methoddoes not have the requirement for the shape of the nickel-titanium shape memory alloy component, and the method is adaptive to the complex nickel-titanium shape memory alloy component and capable of effectively improving the function stability of the complex nickel-titanium shape memory alloy component.

A “negative creep” corrugated gasket of Shape Memory Alloy (SMA) for Bolted Flanged Connections (BFCs) operates under temperatures that are within the temperature interval of reverse martensitic phase transformation from martensite to austenite of the SMA. Gasket corrugation is shape-memorized to operating “swelling” at temperature of direct martensitic phase transformation from austenite to martensite of the SMA being compressed to obtain some quantity of residual contraction corresponding to stress-induced martensite formation. A free “swelling” of deformed gasket corrugation at operating temperature defines the “negative creep” effect of the gasket, and it is blocked by rigid flanges with appearance of reactive shape-recovering stresses between the gasket corrugation and flange surfaces. The reactive shape-recovering stresses have direction inverse to the direction of operating creep of the gasket providing leak-tight, multiple, automatic and continuous seal between the flanges of the BFC. Methods of manufacturing of “negative creep” corrugated gasket are disclosed.

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 laser additive manufacturing shear type phase change crack resistance method. The method comprises the steps of adopting a laser additive manufacturing technology and takinghigh-entropy alloy powder with FCC-HCP martensite phase change as additive manufacturing special powder; drying the metal powder in a vacuum drying oven for 12 hours at a drying temperature of 120 DEGC; and carrying out additive manufacturing and printing on the dried high-entropy alloy powder, wherein the printing parameters are as follows: the laser power is 400 W, the scanning speed is 800-1600 mm/s, the scanning distance is 0.09 mm, the powder laying thickness is 0.03 mm, and the substrate preheating temperature is 100 DEG C. The problem of metallurgical defects such as thermal crack deformation and the like are caused by high temperature and high stress gradient in a molten pool in the traditional laser additive manufacturing process is solved. On the basis of the study, the idea ofsuppressing hot cracks in additive manufacturing alloys by stress-induced martensitic transformation is extended to other additive manufacturing alloy systems, and a new method is provided for additive manufacturing of crack-free alloys.

Shapeable guide wire devices and methods for their manufacture. Guide wire devices include an elongate shaft member having a shapeable distal end section that is formed from a linear pseudoelastic nickel-titanium (Ni—Ti) alloy that has linear pseudoelastic behavior without a phase transformation or onset of stress-induced martensite. Linear pseudoelastic Ni—Ti alloy, which is distinct from non-linear pseudoelastic (i.e., superelastic) Ni—Ti alloy, is highly durable, corrosion resistant, and has high stiffness. The shapeable distal end section is shapeable by a user to facilitate guiding the guide wire through tortuous anatomy. In addition, linear pseudoelastic Ni—Ti alloy is more durable tip material than other shapeable tip materials such as stainless steel.

The invention discloses a nickel-titanium shape memory alloy capable of simultaneously realizing the functions of energy absorption and vibration reduction, and a preparation method and application thereof, and relates to the technical field of NiTi shape memory alloys. A cold-deformed nickel-rich NiTi alloy is used for preparing a hand-shaped structure with a negative poisson ratio characteristic, and the phase change behavior and mechanical property of the NiTi alloy are regulated and controlled through heat treatment to a cold-deformed nickel-rich NiTi alloy component. Thus, stress-inducedmartensitic transformation occurs to the NiTi alloy component in the impact deformation process, and large impact energy is absorbed. The deformed NiTi alloy component is kept in a martensite state, and energy dissipation is promoted due to interaction between martensite variants, so that the component has higher damping performance after completion of impact, and a good damping effect is achieved.

The invention relates to the technical field of biomedical shape memory composite materials, in particular to an Nb coated NiTi shape memory composite material and a preparation method thereof. According to the method, the prepared composite material has good biocompatibility, high stress-induced martensite phase transformation critical stress and large recoverable dependent variable, the problemthat an existing single biomedical shape memory alloy, such as a NiTi-based alloy and a no-Ni beta titanium alloy, cannot has the good biocompatibility, high stress-induced martensite phase transformation critical stress and large recoverable dependent variable at the same time can be solved, and the composite material can be applied to the field of biomedicine.

The invention relates to the technical field of high-carbon steel wire machining, and particularly discloses a high-strength and high-elasticity shape memory alloy chuck for high-carbon steel wire drawing. The high-strength and high-elasticity shape memory alloy chuck comprises two chuck main bodies, NiTi shape memory alloy plates are connected to the opposite surfaces of the two chuck main bodies through mounting plates, iron permeating layers are arranged on the opposite surfaces of the two NiTi shape memory alloy plates, and limiting mechanisms are arranged on the opposite surfaces of the two mounting plates. The mechanical characteristic that NiTi shape memory alloy stress induces martensite inverse phase transformation is applied, flexible loading is conducted on the clamped high-carbon steel wire, a stress platform is generated in the loading process, that is, the stress does not change along with the increase of deformation, and therefore it is guaranteed that the high-carbon steel wire does not generate stress concentration at the chuck position, the steel wire is prevented from being broken, the drawing efficiency of the high-carbon steel wire is improved, the iron permeating layer is attached to the surface of the NiTi shape memory alloy plate through a double glow plasma alloying technology, and the surface hardness of the NiTi shape memory alloy plate is improved.