CN107488803A - Magnesium-yttrium-transition metal high-entropy alloy before a kind of bio-medical - Google Patents

Abstract

The invention provides the multicomponent " high-entropy alloy " that one kind is prepared using transiting group metal elements before titanium, zirconium, niobium, tantalum, molybdenum etc. as constituent element, it is characterised in that：Transiting group metal elements Ti, Zr, Nb, Ta are constituent element before the alloy, and its Components Chemical expression formula is：Ti_aZr_bNb_cTa_d, wherein a, b, c, d expression atom content percentage, and a=20 30, b=20 30, c=20 30, d=20 30, a+b+c+d=100；Mo, Si, Cu, Ag element can also be added in right amount in the alloy.The high-entropy alloy has the characteristics that body-centred cubic crystal structure and high intensity, high rigidity, corrosion-resistant, biocompatibility is good, is suitable as bio-medical hard tissue repair and is used with alternative materials.

Description

A biomedical pre-transition metal high-entropy alloy

technical field

The invention relates to high-entropy alloys with multi-element chemical composition and nearly equiatomic ratio or equiatomic ratio characteristics, and particularly provides a class of high-entropy alloys of pre-transition group metals that can be prepared by vacuum non-consumable arc melting technology.

Background technique

In the chemical composition of traditional solid solution alloys, a certain metal element is used as the main element matrix, and an appropriate amount of alloy elements are added according to the performance requirements to form gaps or replace solid solution phases to obtain optimized comprehensive properties. The physical, chemical, mechanical properties and biocompatibility of alloys mainly depend on the properties of matrix elements. The alloy composition is at the end of the thermodynamic equilibrium phase diagram, which may be accompanied by the formation of a small amount of intermetallic compound phase.

"High-entropy alloys" mainly refer to alloys with large configuration entropy. Usually, elements with similar chemical properties and atomic sizes are selected in alloy design, and are composed of at least five components in stoichiometric ratios of equiatomic ratios or near equiatomic ratios. The alloy forms a solid solution structure with a crystal structure of face-centered cubic (fcc) or body-centered cubic (bcc) in terms of phase selection. Current research shows that this type of alloy has the following characteristics in terms of performance: (1) High strength and high hardness. For example, the yield strength and Vickers hardness of WNbMoTaV quinary alloy are 1250MPa and 5.3GPa, respectively. (2) High fracture toughness. For example, the fracture toughness of CrMnFeCoNi five-element alloy reaches 220MPa·m ^1/2 , surpassing ordinary stainless steel and titanium alloy. (3) Good corrosion resistance. For example, the corrosion potential of FeCoCrNi quaternary alloy in 3.5% NaCl solution is equivalent to that of 304L stainless steel, and its potential for pitting corrosion is higher, while the corrosion current density can be reduced by about an order of magnitude. The corrosion resistance of Cu _0.5 NiAlCoCrFeSi seven-element alloy in H ₂ SO ₄ aqueous solution is better than that of 304 stainless steel, but its corrosion resistance in the environment containing Cl ^- is not as good as that of 304 stainless steel. (4) Wear resistance and oxidation resistance. The wear resistance of CuCoNiCrAl _0.5 FeB _x alloy is better than that of 316 stainless steel, Co-based alloy, SUJ2 bearing steel and SKD61 hot work die steel under the same working conditions. AlSiTiCrFeCoNiMo _0.5 alloy exhibits better wear resistance than SUJ2 bearing steel and SKD61 hot work die steel, and has excellent high temperature oxidation resistance.

Multicomponent "high entropy alloys" can usually be prepared by vacuum arc melting. For alloy systems containing low melting point and volatile components, resistance heating or induction heating are usually used for melting. Thermal spraying technology can also be used to prepare "high entropy alloy" coatings, etc.

"High-entropy alloys" have excellent properties such as high strength, high toughness, and wear resistance, which are expected to meet the needs of certain structural parts or surface coating applications in the fields of aviation, chemical industry, and microelectronics, and also have good biomedical potential.

Biomedical hard tissue repair and replacement, especially joint prosthesis replacement, requires materials with high strength, excellent wear resistance and biocompatibility. Stainless steel, titanium alloys and cobalt-chromium-molybdenum alloys commonly used in clinical practice cannot fully meet all performance requirements, such as pitting corrosion of stainless steel, poor wear resistance of titanium alloys, and release of toxic metal ions from cobalt-chromium-molybdenum alloys. application.

The invention mainly aims at the requirement of biomedical device components that can be used for implantation in the human body, and provides a new type of "high-entropy alloy", which has the characteristics of high strength, corrosion resistance and good biocompatibility.

Contents of the invention

The invention provides a class of multi-element "high-entropy alloys" prepared with titanium, zirconium, niobium, tantalum, molybdenum and other former transition group metal elements as components, which have a body-centered cubic crystal structure and high strength and high hardness , corrosion resistance, good biocompatibility and other characteristics, suitable for use as biomedical hard tissue repair and replacement materials.

The present invention specifically provides a novel biomedical pre-transition group metal high-entropy alloy, which is characterized in that: the alloy is composed of pre-transition group metal elements Ti, Zr, Nb, and Ta, and its composition chemical expression is: Ti _a Zr _b Nb _c Ta _d , where a, b, c, d represent atomic content percentage, and a=20-30, b=20-30, c=20-30, d=20-30, a+b+c +d=100. Within this chemical composition range, alloy compositions with good comprehensive mechanical properties and corrosion resistance in environments containing chloride ions can be further optimized.

The high-entropy alloy of the former transition group metals of the present invention is characterized in that: the alloy is composed of former transition group metal elements Ti, Zr, Nb, Ta, Mo, and its composition chemical expression is: Ti _a Zr _b Nb _c Ta _d Mo _e , wherein a, b, c, d, e represent the atomic content percentage, and a=19.6-25, b=19.6-25, c=19.6-25, d=19.6-25, e=0.5-20 , a+b+c+d+e=100.

Among the high-entropy alloys, the preferred alloy composition is: Ti, Zr, Nb, and Ta four elements are prepared in an equiatomic ratio, the atomic ratio is 1:1:1:1, and the content of each atomic percentage is 20%-24.875 %, that is, the mass percentages are 9.41%-11.55%, 17.92%-21.99%, 18.25%-22.40%, 35.55%-43.62%; the atomic percentage of Mo is 0.5-20%, that is, the mass percentage 0.46-18.86%. Within this chemical composition range, alloy compositions with good comprehensive mechanical properties and corrosion resistance in environments containing chloride ions can be further optimized.

The high-entropy alloy of metals of the pre-transition group in the present invention is characterized in that: an appropriate amount of Si element can be added to the high-entropy alloy, and the chemical expression of its composition is: Ti _a Zr _b Nb _c Ta _d Mo _e Si _f , wherein a=19.6-25, b=19.6-25, c=19.6-25, d=19.6-25, e=0.5-20, f=0.5-2, a+b+c+d+e+f=100.

In the high-entropy alloy, the preferred alloy composition is: Ti, Zr, Nb, and Ta four elements are prepared according to the equiatomic ratio (ie a:b:c:d=1:1:1:1), and its atomic percentage The content is 19.6%-24.75%, that is, the mass percentage is 9.34%-11.54%, 17.79%-21.97%, 18.12%-22.37%, 35.30%-43.57%; the atomic percentage of Mo is 0.5-20% , that is, the mass percentage is 0.46-19.11%; the atomic percentage of Si is 0.5%-2%, that is, the mass percentage is 0.09%-0.41%. Within this chemical composition range, alloy compositions with good comprehensive mechanical properties and corrosion resistance in environments containing chloride ions can be further optimized.

The high-entropy alloy of metals of the pre-transition group in the present invention is characterized in that: an appropriate amount of Cu element can be added to the high-entropy alloy, and the chemical expression of its composition is: Ti _a Zr _b Nb _c Ta _d Mo _e Cu _m , a =19.6-25, b=19.6-25, c=19.6-25, d=19.6-25, e=0.5-20, m=0.5-1, a+b+c+d+e+m=100.

In the high-entropy alloy, the preferred alloy composition is: Ti, Zr, Nb, and Ta four elements are prepared according to the equiatomic ratio (ie a:b:c:d=1:1:1:1), and its atomic percentage The content is 19.75%-24.75%, that is, the mass percentages are 9.33%-11.51%, 17.76%-21.92%, 18.09%-22.33%, 35.24%-43.48%; the atomic percentage of Mo is 0.5-20% , that is, the mass percentage is 0.46-18.93%; the atomic percentage of Cu is 0.5%-1%, that is, the mass percentage is 0.30%-0.63%. Within this chemical composition range, alloy compositions with good comprehensive mechanical properties and corrosion resistance in environments containing chloride ions can be further optimized.

The high-entropy alloy of the pre-transition group metals of the present invention is characterized in that: an appropriate amount of Ag element can be added to the high-entropy alloy, and the chemical expression of its composition is: Ti _a Zr _b Nb _c Ta _d Mo _e Ag _n , a =19.6-25, b=19.6-25, c=19.6-25, d=19.6-25, e=0.5-20, n=0.5-1, a+b+c+d+e+n=100.

In the high-entropy alloy, the preferred alloy composition is: Ti, Zr, Nb, and Ta four elements are prepared according to the equiatomic ratio (ie a:b:c:d=1:1:1:1), and its atomic percentage The content is 19.75%-24.75%, that is, the mass percentages are 9.29%-11.49%, 17.69%-21.88%, 18.01%-22.28%, 35.09%-43.39%; the atomic percentage of Mo is 0.5-20% , that is, the mass percentage is 0.46-18.85%; the atomic percentage of Ag is 0.5%-1%, that is, the mass percentage is 0.52%-1.06%. Within this chemical composition range, alloy compositions with good comprehensive mechanical properties and corrosion resistance in environments containing chloride ions can be further optimized.

Among the components of the "high-entropy alloy" described in the present invention, Ti, Zr, Nb, Ta and other components can be infinitely soluble, forming an infinite solid solution of bcc structure of β phase at high temperature, and forming an infinite solid solution of hcp structure of α phase when cooled to room temperature ; Mo, Nb, and Ta can also dissolve infinitely, forming an infinite solid solution with a bcc structure; while the solid solubility of Mo in Zr is only 10 at.%, it will form a Mo ₂ Zr intermediate phase with Zr. Due to the mixing and smelting of each component in the alloy with near equiatomic ratio, the higher configuration entropy inhibits the formation of Mo ₂ Zr intermediate phase, and keeps the high temperature β phase, forming a simple bcc crystal structure.

Among the components of the high-entropy alloy described in the present invention, the atomic radii of Ti, Nb, Ta, and Mo are similar, being respectively 0.147nm, 0.147nm, 0.147nm, and 0.140nm, while the atomic radius of Zr is the largest, being 0.160nm. Size mismatch can be up to 20%. The mismatch of atomic size leads to severe distortion of the lattice lattice, which generates a strong distortion strain field and hinders the movement of dislocations. At the same time, the shear moduli of Ti, Zr, Nb, Ta, and Mo are 44GPa, 33GPa, 38GPa, 69GPa, and 126GPa, respectively, and the maximum modulus mismatch can reach 117%. The modulus mismatch adds additional resistance to the relative slip of the atomic planes above and below the slip plane, making it more difficult for dislocations to slip. Under the combined effects of size mismatch and modulus mismatch, the high-entropy alloy exhibits excellent mechanical properties. At the same time, adding a trace amount of Si element can further improve the strength of the alloy. The compressive yield strength of the high-entropy alloy reaches 900-1600MPa, the compressive plastic strain exceeds 5%, and the Vickers hardness reaches 3-5GPa.

In the high-entropy alloy described in the present invention, components such as Ti, Zr, Nb, Ta, Mo have good biocompatibility, and can form a dense passivation film in a corrosive environment to prevent a large amount of dissolution of metal ions; meanwhile, these components The metal ions dissolved by elemental corrosion will not cause negative responses of cells and the immune system; the addition of trace amounts of Cu and Ag elements also has antibacterial effects.

The high-entropy alloy provided by the invention shows good corrosion resistance in phosphate buffer and body temperature environment, no pitting occurs, the corrosion potential reaches -600-700mV (relative to saturated calomel electrode), and the corrosion current density reaches 0.03 -0.05μA/cm ² , the passivation current density reaches 0.8-1.5μA/cm ² . A dense passivation film is formed on the surface of the alloy without pitting corrosion.

The high-entropy alloy of the present invention is smelted in a vacuum non-consumable electric arc furnace, and its basic preparation process is as follows: commercially available raw materials (purity not less than 99.5wt.%) of components such as Ti, Zr, Nb, Ta, Mo, etc. ) is formulated according to the given alloy composition expression, and melted in a water-cooled copper crucible in a non-consumable tungsten electrode vacuum electric arc furnace, and the furnace chamber is protected by high-purity argon. The smelting of each step needs to turn over the alloy ingot and repeat it several times until the composition of the alloy is uniform.

A small amount of impurities, such as hydrogen, oxygen, nitrogen, phosphorus, etc., are allowed to exist in the high-entropy alloy of the present invention, and the impurity elements mainly come from the starting materials, the atmosphere in the alloy smelting process, the crucible material, etc.

Description of drawings

Below in conjunction with accompanying table and embodiment the present invention is described in further detail:

Fig. 1 is the X-ray diffraction spectrum of the example alloy prepared by arc melting.

Fig. 2 is the compressive engineering stress-engineering strain curve of the example alloy prepared by arc melting.

Fig. 3 is the zeta potential polarization curve of the example alloy prepared by arc melting in phosphate buffer solution and body temperature environment.

detailed description

Example 1

Ti ₂₅ Zr ₂₅ Nb ₂₅ Ta ₂₅ alloy ingot prepared by vacuum non-consumable arc melting (nominal composition is atomic percentage, the same below)

Using commercially available pure metal Ti, Zr, Nb, Ta element rods, blocks and other bulk materials (purity higher than 99.5%, mass percentage) as starting materials, arc melting in a titanium-purified argon atmosphere into quaternary Master alloy ingot. The alloy ingot needs to be smelted several times to ensure the uniformity of the composition.

Cut a block sample of 5mm×5mm×1mm from the alloy ingot, and use it for X-ray diffraction (XRD) analysis after mechanical grinding. It is a single-phase bcc structure, and the diffraction spectrum is shown in Figure 1. A block sample of 8 mm × 8 mm × 2 mm was cut from the alloy ingot. After hot-mounting, it underwent strict mechanical grinding and polishing, and the Vickers hardness was measured on a Vickers microhardness tester at room temperature. The results are shown in Table 1. A cylindrical compression sample with a height-to-diameter ratio of 2:1 was cut from the alloy ingot, and after rigorous mechanical grinding, the compression test was carried out at room temperature with a head speed of 0.05mm/min (corresponding to an initial strain rate of 8.33×10 ^-4 s ^-1 ), the measurement results are shown in Figure 2 and Table 1. A block sample of 5 mm × 5 mm × 5 mm was cut from the alloy ingot, and after rigorous mechanical grinding, electrochemical measurements were performed on an electrochemical workstation using a standard three-electrode electrolytic cell. Wherein, the measurement temperature is 37°C, the sample to be tested is the working electrode, the saturated calomel electrode (SCE) is the reference electrode, the platinum electrode is the counter electrode, and the test solution is phosphate buffer. The measurement results are shown in Figure 3 and Table 2, and no pitting occurs.

Example 2

Preparation of Ti _22.5 Zr _22.5 Nb _22.5 Ta _22.5 Mo ₁₀ Alloy Ingots by Non-Consumable Vacuum Arc Melting

Using commercially available pure metal Ti, Zr, Nb, Ta, Mo elements such as rods, blocks, etc. Five-element master alloy ingot. The alloy ingot needs to be smelted several times to ensure the uniformity of the composition. The same method as in Example 1 was used to measure the crystal structure, hardness, compressive properties and electrochemical behavior of the alloy. The composition alloy has a two-phase bcc structure, and pitting corrosion does not occur in PBS solution. The corresponding measurement results are shown in Figures 1, 2, 3 and Tables 1 and 2.

Example 3

Preparation of Ti _21.25 Zr _21.25 Nb _21.25 Ta _21.25 Mo ₁₅ Alloy Ingots by Non-Consumable Vacuum Arc Melting

Using commercially available pure metal Ti, Zr, Nb, Ta, Mo elements such as rods, blocks, etc. Five-element master alloy ingot. The alloy ingot needs to be smelted several times to ensure the uniformity of the composition. The same method as in Example 1 was used to measure the crystal structure, hardness, compressive properties and electrochemical behavior of the alloy. The composition alloy has a two-phase bcc structure, and pitting corrosion does not occur in PBS solution. The corresponding measurement results are shown in Figures 1, 2, 3 and Tables 1 and 2.

Example 4

Preparation of Ti ₂₀ Zr ₂₀ Nb ₂₀ Ta ₂₀ Mo ₂₀ Alloy Ingots by Non-Consumable Vacuum Arc Melting

Using commercially available pure metal Ti, Zr, Nb, Ta, Mo elements such as rods, blocks, etc. Five-element master alloy ingot. The alloy ingot needs to be smelted several times to ensure the uniformity of the composition. The same method as in Example 1 was used to measure the crystal structure, hardness, compressive properties and electrochemical behavior of the alloy. The composition alloy has a two-phase bcc structure, and pitting corrosion does not occur in PBS solution. The corresponding measurement results are shown in Figures 1, 2, 3 and Tables 1 and 2.

Example 5

Preparation of Ti _19.8 Zr _19.8 Nb _19.8 Ta _19.8 Mo _19.8 Si ₁ Alloy Ingot by Non-Consumable Vacuum Arc Melting

Using commercially available pure metal Ti, Zr, Nb, Ta, Mo, Si elements such as rods, blocks, sheets and other bulk materials (purity higher than 99.5%, mass percentage) as starting materials, in an argon atmosphere purified by titanium The lower electric arc is smelted into a five-element master alloy ingot. The alloy ingot needs to be smelted several times to ensure the uniformity of the composition. The same method as in Example 1 was used to measure the crystal structure, hardness, compressive properties and electrochemical behavior of the alloy. The composition alloy has a single-phase bcc structure, and no pitting corrosion occurs in PBS solution. The corresponding measurement results are shown in Figures 1, 2, 3 and Tables 1 and 2.

Example 6

Preparation of Ti _19.8 Zr _19.8 Nb _19.8 Ta _19.8 Mo _19.8 Cu ₁ Alloy Ingot by Non-Consumable Vacuum Arc Melting

Using commercially available pure metal Ti, Zr, Nb, Ta, Mo, Cu and other bulk materials (purity higher than 99.5%, mass percentage) as starting materials, in an argon atmosphere purified by titanium The lower electric arc is smelted into a five-element master alloy ingot. The alloy ingot needs to be smelted several times to ensure the uniformity of the composition. The same method as in Example 1 was used to measure the crystal structure, hardness, compressive properties and electrochemical behavior of the alloy. The composition alloy has a two-phase bcc structure, and pitting corrosion does not occur in PBS solution. The corresponding measurement results are shown in Figures 1, 2, 3 and Tables 1 and 2.

Example 7

Preparation of Ti _19.8 Zr _19.8 Nb _19.8 Ta _19.8 Mo _19.8 Ag ₁ Alloy Ingot by Non-Consumable Vacuum Arc Melting

Using commercially available pure metal Ti, Zr, Nb, Ta, Mo, Ag and other bulk materials (purity higher than 99.5%, mass percentage) as starting materials, in an argon atmosphere purified by titanium The lower electric arc is smelted into a five-element master alloy ingot. The alloy ingot needs to be smelted several times to ensure the uniformity of the composition. The same method as in Example 1 was used to measure the crystal structure, hardness, compressive properties and electrochemical behavior of the alloy. The composition alloy has a two-phase bcc structure, and pitting corrosion does not occur in PBS solution. The corresponding measurement results are shown in Figures 1, 2, 3 and Tables 1 and 2.

Compressive yield strength (σ _y ), compressive plasticity (ε _p ) and Vickers hardness (H _v ) of table 1 embodiment alloy

The measurement results of the potentiodynamic polarization curves of the alloys in Table 2 in phosphate buffer and body temperature environment, including corrosion potential (E _corr ), corrosion current density (I _corr ) and passivation current density (I _p )

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and not to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. A kind of 1. magnesium-yttrium-transition metal high-entropy alloy before bio-medical, it is characterised in that：The alloy with Ti, Zr, Nb, Ta are constituent element, and its Components Chemical expression formula is：Ti_aZr_bNb_cTa_d, wherein a, b, c, d Represent atom content percentage, and a=20-30, b=20-30, c=20-30, d=20-30, a+b+c+d=100.
2. 2. according to preceding magnesium-yttrium-transition metal high-entropy alloy described in claim 1, it is characterised in that：The height Mo elements are added in entropy alloy, its Components Chemical expression formula is：Ti_aZr_bNb_cTa_dMo_e, wherein a, B, c, d, e represent atom content percentage, and a=19.6-25, b=19.6-25, c=19.6-25, d=19.6-25, E=0.5-20, a+b+c+d+e=100.
3. 3. according to preceding magnesium-yttrium-transition metal high-entropy alloy described in claim 2, it is characterised in that：Ti、Zr、 The atom content ratio of tetra- kinds of elements of Nb, Ta is a:b:c:D=1:1:1:1, and every kind of element its atomic percent contains Measure as 20-24.875%, i.e. a=20-24.875, b=20-24.875, c=20-24.875, d=20-24.875.
4. 4. according to preceding magnesium-yttrium-transition metal high-entropy alloy described in claim 2, it is characterised in that：Described Si elements are added in high-entropy alloy, its Components Chemical expression formula is：Ti_aZr_bNb_cTa_dMo_eSi_f, wherein, A=19.6-25, b=19.6-25, c=19.6-25, d=19.6-25, e=0.5-20, f=0.5-2, A+b+c+d+e+f=100.
5. 5. according to preceding magnesium-yttrium-transition metal high-entropy alloy described in claim 4, it is characterised in that：Ti、Zr、 The atom content ratio of tetra- kinds of elements of Nb, Ta is a:b:c:D=1:1:1:1, and every kind of element its atomic percent contains Measure as 19.6-24.75%, i.e. a=19.6-24.75, b=19.6-24.75, c=19.6-24.75, d=19.6-24.75.
6. 6. according to preceding magnesium-yttrium-transition metal high-entropy alloy described in claim 2, it is characterised in that：Described Cu elements are added in high-entropy alloy, its Components Chemical expression formula is：Ti_aZr_bNb_cTa_dMo_eCu_m, its In, a=19.6-25, b=19.6-25, c=19.6-25, d=19.6-25, e=0.5-20, m=0.5-1, A+b+c+d+e+m=100.
7. 7. according to preceding magnesium-yttrium-transition metal high-entropy alloy described in claim 6, it is characterised in that：Ti、Zr、 The atom content ratio of tetra- kinds of elements of Nb, Ta is a:b:c:D=1:1:1:1, and every kind of element its atomic percent contains Measure as 19.75-24.75%, i.e. a=19.75-24.75, b=19.75-24.75, c=19.75-24.75, D=19.75-24.75.
8. 8. according to preceding magnesium-yttrium-transition metal high-entropy alloy described in claim 2, it is characterised in that：Described Ag elements are added in high-entropy alloy, its Components Chemical expression formula is：Ti_aZr_bNb_cTa_dMo_eAg_n, its In, a=19.6-25, b=19.6-25, c=19.6-25, d=19.6-25, e=0.5-20, n=0.5-1, A+b+c+d+e+n=100.
9. 9. according to preceding magnesium-yttrium-transition metal high-entropy alloy described in claim 8, it is characterised in that：Ti、Zr、 The atom content ratio of tetra- kinds of elements of Nb, Ta is a:b:c:D=1:1:1:1, and every kind of element its atomic percent contains Measure as 19.75-24.75%, i.e. a=19.75-24.75, b=19.75-24.75, c=19.75-24.75, D=19.75-24.75.
10. 10. according to any preceding magnesium-yttrium-transition metal high-entropy alloy of claim 2,4,6,8, it is special Sign is：In the high-entropy alloy, the atom content ratio of tetra- kinds of elements of Ti, Zr, Nb, Ta is a:b:c:D=1:1:1:1.