WO2017003192A1

WO2017003192A1 - Tini-based medical alloy and method for producing same

Info

Publication number: WO2017003192A1
Application number: PCT/KR2016/006987
Authority: WO
Inventors: 강지훈
Original assignee: (주)강앤박메디컬
Priority date: 2015-06-30
Filing date: 2016-06-29
Publication date: 2017-01-05

Abstract

The present invention relates to a TiNi-based medical alloy and a method for producing same. The TiNi-based medical alloy consisting of 44-48 wt% of Ti, 0.2-3.0 wt% of Mo, 0.1-2.0 wt% of Fe, 0.2-1.0 wt% of Al and the remainder of Ni has a high level of physical and mechanical properties and provides various features suitable for medical use.

Description

TiNi-based medical alloy and its manufacturing method

The present invention relates to a TiNi-based medical alloy, including Ti, Ni, Mo, Fe, and Al, which can provide various properties suitable for medical use while having high physical and mechanical properties, and a method for manufacturing the same.

As is well known, TiNi-based alloys are widely used in the clinic, which exhibit unique characteristics such as shape memory effects, superelasticity, high corrosion resistance, strength, etc., and are able to withstand large loads under constant stress without permanent plastic deformation. Its use is increasing for medical use.

Medical device design engineers, meanwhile, are paying attention to various forms of TiNi-based alloys for use in new medical purposes such as surgical techniques, which not only understand the properties of all materials, but also stress-strain dependence and dynamics. Predicting behavior is very important.

Despite the well-known advantages of TiNi-based alloys, they are expensive to manufacture, and alloys are generally manufactured by techniques such as vacuum induction melting (VIM), arc melting, etc. to obtain ingots. Can be. Since such alloys require a sufficient mechanical treatment step and repeated heat treatment (process heat treatment), the alloy manufacturing cost can be increased.

On the other hand, attempts have been made to find effective melting / dissolving methods for producing alloys containing highly reactive metals. However, attempts to produce highly reactive titanium alloys by melting methods have been performed with invasive elements such as oxygen and hydrogen. Due to the high reactivity of the molten titanium is undergoing a lot of trial and error.

In this example, alloys of highly reactive metals are generally produced by arc melting, for example TiNi-based alloys are produced by consumable and non-consumable arc melting, firstly, complete control over the melting process and alloy composition is difficult, and secondly However, there is a problem that an expensive multi-arc melting process is required to achieve chemical homogeneity.

On the other hand, TiNi-based medical alloys with superelastic properties are widely used for medical purposes because of their high kinematic properties, suitability, and safety for human tissues, but they are difficult to work on cutting, pressing, and punching due to their rigidity and adhesion. Is a TiNi-based medical alloy that can be severely altered by mechanical treatment and heat treatment and cast into medical implants (eg, for clasp dentures, etc.) by the similarity of living tissue in terms of stress-strain (strength-elongation) behavior. Silver can be prepared using a vacuum induction (VIM) process.

However, superelastic TiNi-based implants with stress-strain characteristics similar to human tissues (bones, cartilage, tendons) are known to be inherently difficult to regenerate if damaged after internal implantation, but are actually difficult to regenerate Or because the rupture of the implanted product (sealing material, etc.) is an important problem to be solved in order to be used for medical purposes, it is very important to improve the properties of TiNi-based alloys including tensile strength and the like.

[Preceding technical literature]

[Patent Documents]

1. Registered Patent No. 10-0490644 (registered on May 11, 2005): Ni-Ti shape memory alloy for medical devices having a TiN coating layer and a manufacturing method thereof

The present invention is to provide a TiNi-based medical alloy containing Ti, Ni, Mo, Fe and Al, and can provide a variety of properties suitable for medical use while having high physical and mechanical properties and a method of manufacturing the same.

In addition, the present invention is charged with the structural strength, elastic properties, tissue compatibility, wear resistance, through vacuum induction after charging Ti, Ni, Mo, Fe and Al in the graphite crucible in a vacuum induction method (VIM) in an argon atmosphere An object of the present invention is to provide a TiNi-based medical alloy having improved properties suitable for use in medical applications such as life cycle and strain life.

The objects of the embodiments of the present invention are not limited to the above-mentioned objects, and other objects, which are not mentioned above, will be clearly understood by those skilled in the art from the following description. .

According to one aspect of the present invention, a TiNi-based medical alloy may be provided, which is composed of Ti 44-48 wt%, Mo 0.2-3.0 wt%, Fe 0.1-2.0 wt%, Al 0.2-1.0 wt%, and balance Ni.

According to another aspect of the present invention, alloy components consisting of Ti 44-48 wt%, Mo 0.2-3.0 wt%, Fe 0.1-2.0 wt%, Al 0.2-1.0 wt% and balance Ni are dissolved using high frequency vacuum induction. And hot forging and hot extruding the alloy ingot obtained through the dissolving step, repeating the cold drawing and annealing at an intermediate temperature after the hot forging and hot extrusion, and the annealing. After the step of repeating, after the solution treatment for 0.5-1.5 hours at a temperature of 973K-1173K quenched to prepare a TiNi-based medical alloy comprising the step of producing a TiNi-based medical alloy.

The present invention includes Ti, Ni, Mo, Fe and Al, and can provide a TiNi-based medical alloy having high physical and mechanical properties and can provide a variety of properties suitable for medical use.

In addition, the present invention is charged with the structural strength, elastic properties, tissue compatibility, wear resistance, through vacuum induction after charging Ti, Ni, Mo, Fe and Al in the graphite crucible in a vacuum induction method (VIM) in an argon atmosphere It is possible to provide a TiNi-based medical alloy having improved properties suitable for use in medical applications, such as life cycle, strain life.

1A to 1E are diagrams for explaining the distribution of grain sizes in an Al-added TiNi-based alloy according to an embodiment of the present invention.

2 is a diagram showing a stress strain of a conventional TiNi-based alloy containing no Al,

3 is a view showing the maximum tensile strength and total elongation of the TiNi-based medical alloy according to an embodiment of the present invention,

4 is a view showing the temperature dependence of the martensite transformation of the TiNi-based medical alloy according to an embodiment of the present invention.

Advantages and features of the embodiments of the present invention, and methods of achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

In describing the embodiments of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the embodiments of the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the contents throughout the specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the TiNi-based medical alloy according to the embodiment of the present invention may be composed of Ti 44-48 wt%, Mo 0.2-3.0 wt%, Fe 0.1-2.0 wt%, Al 0.2-1.0 wt% and the balance Ni.

Here, since Ti is less than 44 wt% or more than 48 wt%, the restoring force and the damping effect below the transition temperature are remarkably inferior, and therefore, Ti is preferably added at a ratio of 44-48 wt%.

In addition, Mo may increase the strength and hardenability when added to the alloy, but the amount of addition may vary depending on the use of the alloy because the weldability is deteriorated, and when it is less than 0.2% by weight, the strength and the hardenability are increased. Since it is impossible to obtain and weldability falls when it exceeds 3.0 weight%, it is preferable to add in the ratio of 0.2-3.0 weight%.

In addition, Fe plays a role of stabilizing the β phase when added to the alloy, if the addition amount is less than 0.1% by weight there is a problem that can not sufficiently stabilize the β phase at room temperature, when the strength exceeds 2.0% by weight Since creep strength decreases while increasing, it is preferably added at a ratio of 0.1-2.0% by weight.

On the other hand, when Al is added to the alloy, the α phase is strengthened, and as its content is increased, the strength may be increased by solid solution to titanium (Ti) base, and the specific density of the alloy may be reduced by decreasing the density of the alloy. strength), but if the amount is less than 0.2% by weight, there is a problem in that the density reduction effect is not large and the strength is lowered.In the case of more than 1.0% by weight, Ti ₃ Al is formed so that the ductility of titanium Since it is sharply lowered, it is preferable to add it in the ratio of 0.2-1.0 weight%.

On the other hand, the manufacturing method of the TiNi-based medical alloy according to the present invention, alloy components consisting of Ti 44-48% by weight, Mo 0.2-3.0% by weight, Fe 0.1-2.0% by weight, Al 0.2-1.0% by weight and the balance Ni After the step of melting using high frequency vacuum induction, hot forging and hot extrusion of the alloy ingot obtained through the step of melting, and the step of hot forging and hot extrusion, cold drawing and annealing at an intermediate temperature are performed. After the step of repeating, and repeating the annealing, comprising the step of quenching after solution treatment for 0.5-1.5 hours at a temperature of 973K-1173K, to prepare a TiNi-based medical alloy according to an embodiment of the present invention can do.

Here, each of the alloying components can be loaded into granules having a size of 1-3 mm, the resulting TiNi-based medical alloy, the maximum tensile strength can have a range of 1420-1620 Mpa, superelastic section It may have a temperature range of 10-80 ℃.

For example, granular Ti sponge, Ni sheet and mixed alloy additives (including Mo, Fe and Al) are charged into the graphite crucible at a rate selected within the ratios described above, while Ti sponge, Ni sheet and mix The alloy additives (including Mo, Fe and Al) to be stacked in the form of sequentially stacked, and the graphite crucible is put in a vacuum induction melting (VIM) inside, and then the titanium (Ti) in the graphite crucible Ti sponge, Ni sheet, and by induction melting at about 1668 ° C. (titanium melting point higher than nickel melting point) in a vacuum or argon atmosphere maintained at about 3 × 10 ⁻² torr or less to prevent oxidation The alloy additives (including Mo, Fe and Al) to be mixed can be dissolved, and the TiNi-based medical alloy is maintained by maintaining the temperature of about 1350-1450 ° C. and a time of about 2-5 minutes while stirring the induction-melted alloy molten metal. It can be prepared.

Here, since the vacuum induction (VIM) process has a good mixing effect that provides chemical homogeneity of the liquid melt, the TiNi-based alloy can be melted in a low frequency vacuum induction furnace (VIM) furnace, and this low frequency vacuum induction ( The VIM) technique has been described as being used to melt a TiNi-based alloy because it can produce an excellent TiNi-based alloy at low cost, but other dissolution techniques performed in an inert atmosphere can of course be used.

The TiNi-based medical alloy dissolved through the vacuum induction melting (VIM) process as described above is injected into a preheating mold to solidify, and the alloy may be manufactured to have a fine casting surface through a casting process using the preheating mold. It is possible to optimize casting boundaries in thin sections and to minimize porosity in casting sections.

The resulting TiNi-based (including Mo, Fe, and Al) medical alloys have improved properties over conventional nitinol alloys (alloys of nickel and titanium). The physical and mechanical properties of ingots, semi-finished or finished products It can be changed very finely and its casting cost can be reduced as a whole because process steps such as forging, milling and drawing are eliminated or greatly reduced.

On the other hand, the TiNi-based medical alloy sample according to the embodiment of the present invention to prepare and look at the characteristics, the electrolyte Ni plate (99.93% pure), the shape of the sponge Ti (99.74% pure), the alloy components in the form of additives layered The furnace is placed inside a graphite crucible (99.9% pure), the crucible is placed inside an VIM furnace with an argon atmosphere, the VIM furnace is operated at an induction input of approximately 3000 cycles, and the alloying components charged into the crucible are thoroughly mixed. Can be heated at a temperature of approximately 1690-1720 ° C. for effective melting up to (approximately 3.5 minutes) and the alloy melt can be injected into a preheating mold for solidification.

The TiNi-based medical alloy, the result of the casting using the preheating mold, shows good superelasticity, maximum tensile strength is approximately 1420MPa, yield point is approximately 510MPa, total elongation is approximately 64%, superelastic section is 5% elongation, 300MPa It appears in strength, and after 6% deformation, permanent deformation exhibits an improved characteristic of approximately 0.2, indicating that the stress-strain behavior is almost the same as human body tissue, making it suitable for medical use.

On the other hand, in detail with respect to the TiNi-based medical alloy to which Al is added according to an embodiment of the present invention, TiNi-based medical alloy having a superelastic properties in Ti% 44-46, Fe 1.5 or less by weight to increase the tensile strength , Mo 2 or less and residual Ni, and may further be prepared through a casting process, including Al 0.2-1.0.

Such TiNi-based medical alloys are suitable for use in the medical temperature range and strength characteristics of the alloy depending on Fe and Mo, tensile strength is mainly determined by iron (Fe), the alloy is granule (granule, granule) It can be prepared via a vacuum induction (VIM) process using a mixture of raw materials in the form (average granule size 1-3 mm).

Here, the granule size mainly affects the contact surface of alloying elements such as nickel (Ni) and titanium (Ti), and during induction heating the granules interact with other components (interpenetration) and provide additional heat. Process liquid structure, which requires additional heat if the granule (granular) size exceeds approximately 3 mm, and the VIM process is not effective because of the increased technical complexity for dissolution of the alloying components. And when the granule (granular) size is less than approximately 1 mm, an uncontrolled vacuum induction (VIM) reaction occurs because tremendous heat is provided, similar to the self-propagating hihg temperature synthesis method (SHS). There is a problem.

On the other hand, the strength of the alloy is determined by the grain structure and the microstructure including the defects, it is known that the strength characteristics of the grains themselves, not the distribution of grain size is very important.

In addition, the maximum strength characteristic is represented by a fine grain size distribution. In this case, the external load is evenly distributed, and when the grain size distribution is wide, the applied load is unevenly distributed, and as a result, the position where the crack nucleus (path) becomes. It can be localized.

On the other hand, one of the main prerequisites for strengthening the alloy is to obtain the most uniform (homogenous) microstructure, which can be achieved by adding Al to the TiNi-based medical alloy, such as the process described later, due to the high reactivity of Al During the vacuum induction (VIM) process, Al and Ni generate a self-combustion property (SHS), which may promote liquation phase separation, that is, movement of liquid components.

In addition, in the cooling and solidification of the alloy, the newly formed grains of the polycrystalline structure were found to have a smaller average size compared to the alloy containing no Al, and the distribution of the grain size in the Al-added alloy was more uniform. I can see that.

For example, FIGS. 1A to 1C are optical microstructure images of an Al-added TiNi-based alloy, and FIGS. 1D and 1E are SEM images of an Al-added TiNi-based alloy, where 1 is a matrix phase. ), 2 represents fine dispersed precipitates, 3 represents grain boundary dendritic precipitates, and it can be seen that the grain size is uniformly distributed in the Al-added alloy.

This demonstrates that grain growth is inhibited at predicted levels during crystallization in Al-added alloys, which can lead to effects such as: first, active liquid phase mixing of the melt, and second, limited grain growth during solidification. It can be seen.

Meanwhile, when 0.2 wt% or more of Al is added, UTS (Ultimate Tensile Strength: maximum tensile strength) is increased by about 10-15% compared to an unadded TiNi-based alloy, and may be used in medical fields requiring higher UTS.

Here, since the addition of Al exceeding 1% by weight causes the martensite deformation temperature to move to an excessively low temperature, and there is a problem in that a change in the temperature range is severe at low temperatures, the Al addition is 0.2-% by weight. Must be in the range 1.0.

On the other hand, Figure 2 is a diagram showing the stress strain of the conventional TiNi alloy containing no Al, the TiNi-based alloy conventionally does not contain Al 46 wt% Ti, 1.5 wt% Fe, 2 wt% Mo and the balance It can be made of Ni, which is the slope between A and B points in the typical stress-strain curves (strength-elongation curves, Y-axis: strength (MPa), X-axis: strain (%)) of this TiNi-based alloy. The part corresponds to the region where the hyperelasticity appears, and its pressure-strain behavior is due to the reversible martensitic transformation, and further deformation can increase beyond the martensitic transformation range with pressure, corresponding to the C point. It can be seen that the maximum tensile strength (UTS) does not exceed 1400 MPa.

3 is a view showing the maximum tensile strength and total elongation of the TiNi-based medical alloy according to an embodiment of the present invention, Al-added TiNi-based alloy was dissolved using high frequency vacuum induction, the dissolved ingot (ingot) After hot forging and hot extrusion, cold drawing and intermediate annealing were repeated to make a wire rod with a diameter of 1 mm, and a sample cut to the required length (for example, 40 mm, 100 mm, etc.) was approximately 973K-1173K. Samples were prepared by quenching and then quenching for 1 h at.

The maximum tensile strength (UTS) and concentration dependence (left axis: maximum tensile strength (UTS, MPa), right axis: total elongation (TEL,%), X axis: In addition, the maximum tensile strength (UTS) increases with increasing Al content within 30% -27% and shows a range of approximately 1420-16200 MPa. It can be seen that.

4 is a diagram showing the temperature dependence of the martensite transformation of the TiNi-based medical alloy according to an embodiment of the present invention, the maximum tensile strength (UTS) after performing a strain-stress test for each temperature for the TiNi-based medical alloy samples The maximum tensile strength (UTS) over temperature was plotted.

Here, the temperature dependence of the martensitic shear stress of the TiNi-based medical alloy according to the embodiment of the present invention (Y-axis: strength (MPa), X-axis: temperature (℃)), A (approximately) It can be seen that co-existing phases (maternal and martensitic) coexist with each other resulting in a hyperelastic effect, such as the similar dependence mentioned in the former located between points 10 ° C.) and B (approx. 80 ° C.). In addition, it can be seen that the addition amount of Al within 1% by weight corresponds to the temperature range when the superelasticity appears near the human body temperature, and the TiNi-based medical alloy of the present invention to which Al is added within 1% by weight of the human body temperature range It can be seen that superelasticity appears at.

That is, a superelastic section is a section in which a high temperature phase (austenite) and a low temperature phase (martensite) exist together, and the austenite completion temperature (A _r ) and the martensite deformation temperature (M _d or M _s ) Within the zone (ie A _r to M _d ), which may undergo a reaction-organic transformation from the austenite phase to the martensite phase, so that when stress is applied to the alloy, the austenite in response to the applied stress From the transformation from martensite to the undeformed state once the strain is removed.

By the way, in the case of the TiNi-based alloy is not added to the conventional Al, the tensile strength decreases with increasing temperature, while the TiNi-based medical alloy according to the embodiment of the present invention has a specific temperature range (for example, due to Al addition) , 10-80 ℃) shows a tendency to increase the tensile strength, so that when used for medical use can not only prevent damage more effectively, but also for medical use within the body (bio) temperature range (about 37 ℃) It can be seen that suitable superelastic properties are shown below.

As described above, the TiNi-based medical alloy according to the embodiment of the present invention comprises Ti 44-48 wt%, Mo 0.2-3.0 wt%, Fe 0.1-2.0 wt%, Al 0.2-1.0 wt%, and the balance Ni. The maximum tensile strength may have a range of 1420-1620 Mpa, the hyperelastic section may have a temperature range of 10-80 ℃.

Accordingly, the present invention can provide a TiNi-based medical alloy containing Ti, Ni, Mo, Fe and Al, and can provide a variety of properties suitable for medical use while having high physical and mechanical properties.

In addition, the present invention, after charging Ti, Ni, Mo, Fe and Al into the graphite crucible inside the VIM in an argon atmosphere, and vacuum casting induction, alloy casting property, its elasticity and ancillary body dynamic compatibility, strength, corrosion resistance It is possible to provide a TiNi-based medical alloy having improved properties suitable for use in medical applications, such as weakened deformation life, increased durability.

In addition, the TiNi-based medical alloy of the present invention is free from foreign body reactions with biological tissues, and may be present in the human body for a longer period of time. Physical and chemical properties can provide alloys suitable for medical use.

Meanwhile, the TiNi-based medical alloy of the present invention has almost no change in physical properties and thus has high transformation temperature stability, and has a low product cost of less than 5% and a relatively low production cost, compared to the existing product defect of 20-30%. Low profitability improves and is very useful not only for medical use but also for industrial use.

In the foregoing description, various embodiments of the present invention have been described and described, but the present invention is not necessarily limited thereto, and a person having ordinary skill in the art to which the present invention pertains may have various modifications without departing from the technical spirit of the present invention. It will be readily appreciated that branch substitutions, modifications and variations are possible.

Claims

A TiNi-based medical alloy consisting of 44-48 wt% Ti, 0.2-3.0 wt% Mo, 0.1-2.0 wt% Fe, 0.2-1.0 wt% Al and the balance Ni.
The method of claim 1,

The TiNi-based medical alloy has a maximum tensile strength of 1420-1620 Mpa TiNi-based medical alloy.
The method according to claim 1 or 2,

The TiNi-based medical alloy, the super-elastic section has a temperature range of 10-80 ℃ TiNi-based medical alloy.
Dissolving the alloying components consisting of Ti 44-48 wt%, 0.2-3.0 wt% Mo, 0.1-2.0 wt% Fe, 0.2-1.0 wt% Al and the balance Ni using high frequency vacuum induction,

Hot forging and hot extrusion of the alloy ingot obtained through the dissolving step;

After the hot forging and hot extruding, repeating cold drawing and annealing at an intermediate temperature;

After the step of repeating the annealing, the solution treatment for 0.5-1.5 hours at a temperature of 973K-1173K and then quenched to prepare a TiNi-based medical alloy

Method for producing a TiNi-based medical alloy comprising a.
The method of claim 4, wherein

The dissolving step is a method for producing a TiNi-based medical alloy in which each alloy component is charged into granules having a size of 1-3 mm.
The method according to claim 4 or 5,

The TiNi-based medical alloy, the maximum tensile strength has a range of 1420-1620 Mpa, the superelastic section has a temperature range of 10-80 ℃ a TiNi-based medical alloy manufacturing method.