ZIRCONIUM-BASED METAL GLASS ALLOY
According to the present invention, provided is a zirconium-based metal glass alloy including, in atomic %, 62% or more and 67% or less of zirconium (Zr), 1% or more and 5% or less of niobium (Nb), 0.5% or more and 2% or less of titanium (Ti), 12% or more and 15% or less of copper (Cu), 8% or more and 10% or less of nickel (Ni), and 7.5% or more and 8.5% or less of aluminum (Al), the zirconium-based metal glass alloy having a composition represented by Zr62-67Nb1-5Ti0.5-2Cu12-15Ni8-10Al7.5-8.5.
The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2020-100401, filed on Jun. 9, 2020. The above application is hereby expressly incorporated by reference, in its entirety, into the present application.
BACKGROUND OF THE INVENTIONThe present invention relates to a zirconium (Zr)-based metal glass alloy having high glass forming ability, high strength, high ductility, high corrosion resistance, high viscous workability, precision castability, and high brightness.
At present, a metal glass alloy is known as an amorphous alloy having a wide supercooled liquid region in which a molten liquid alloy is rapidly cooled to be in a glass state having no periodic structure. The metal glass alloys have excellent glass forming ability, a high coefficient of restitution, high strength, excellent castability, excellent corrosion characteristics, and the like, and thus, their applications are expanding to golf clubs, mobile phone frames, micromechanical gears, watch casings, and the like.
As such a metal glass alloy, a zirconium-based bulk metal glass alloy (Zr-based BMG alloy) has been proposed (see JP 2010-144245 A, JP 2012-158794 A, and JP 2016-534227 A).
JP 2010-144245 A discloses a Zr-based metal glass alloy containing, in atomic %, 50% or more and 70% or less of zirconium (Zr), 15% or more and 30% or less of copper (Cu), 5% or more and 15% or less of aluminum (Al), 2% or more and 20% or less of iron (Fe), and more than 0.01% and 0.2% or less of nitrogen (N) as main components.
The Zr-based metal glass alloy disclosed in JP 2010-144245 A is described to have a high ability to form an amorphous phase, have high strength and low Young's modulus, and be economically producible.
JP 2012-158794 A discloses a Cu-free Zr-based metal glass alloy having a composition represented by, in atomic %, Zr75-x-y-zAlxNiy-aMzBa (10≤x≤19, 15≤y≤28, M is Nb or Ta, 0<z≤8, B is Fe or Co, and 0≤a≤8).
The Zr-based metal glass alloy disclosed in JP 2012-158794 A is described to have a large amorphous forming ability and have excellent mechanical properties, workability, and corrosion resistance.
JP 2016-534227 A discloses a zirconium-based alloy metal glass having a composition represented by, in atomic %, Zr70-80Be0.8-5Cu1-15Ni1-15Al1-5 (NbyTi1-y)0.5-3 (atomic fraction y=0.1 to 1) or Zr70-80Be0.8-5 (CuxNi1-x)10-25Al1-5 (NbyTi1-y)0.5-3 (atomic fraction x=0.1 to 0.9, y=0.1 to 1).
The zirconium-based alloy metal glass disclosed in JP 2016-534227 A is described to have a temperature difference between crystallization temperature (Tx) and glass transition temperature (Tg) (DT=ΔTx) of 70 K or more, for example, more than 120 K, have a large glass forming ability, and have a thickness of more than 5 mm, for example, 8 mm to 20 mm.
JP 2009-215610 A discloses a high ductility metal glass alloy having a composition represented by ZraNibCucAld (wherein, in atomic %, a is 60 to 75 atomic %, b is 1 to 30 atomic %, c is 1 to 30 atomic %, and d is 5 to 20 atomic %).
The high ductility metal glass alloy disclosed in JP 2009-215610 A is described to be a high ductility metal glass alloy that has excellent plastic workability and is applicable to metal working processes such as cold pressing.
SUMMARY OF THE INVENTIONIncidentally, the Zr-based metal glass alloys disclosed in JP 2010-144245 A, JP 2012-158794 A, and JP 2016-534227 A are individually excellent in glass forming ability (amorphous forming ability), excellent in mechanical properties such as strength, has excellent workability, corrosion resistance, and the like, has excellent plastic workability and high ductility applicable to metal working processes such as cold pressing. However, there has been a problem that they do not have high glass forming ability, high strength, high ductility, high corrosion resistance, high viscous workability, precision castability, and high brightness.
An object of the present invention is to solve the problem of the conventional techniques, and to provide a zirconium (Zr)-based metal glass alloy having excellent characteristics such as high glass forming ability, high strength, high ductility, high corrosion resistance, high viscous workability, precision castability, and high brightness.
In order to achieve the above object, the present invention provides a zirconium-based metal glass alloy comprising, in atomic %, 62% or more and 67% or less of zirconium (Zr), 1% or more and 5% or less of niobium (Nb), 0.5% or more and 2% or less of titanium (Ti), 12% or more and 15% or less of copper (Cu), 8% or more and 10% or less of nickel (Ni), and 7.5% or more and 8.5% or less of aluminum (Al), the zirconium-based metal glass alloy having a composition represented by Zr62-67Nb1-5Ti0.5-2Cu12-15Ni8-10Al7.5-8.5.
Here, it is preferable that the total sum of the contents of Zr, Nb, and Ti (Zr+Nb+Ti) in atomic % is 65% or more and 70% or less.
In addition, it is preferable that the sum of the contents of Nb and Ti (Nb+Ti) in atomic % is 5% or less, and the ratio of the contents of Nb and Ti (Nb/Ti) is 1.0 or more and 8.0 or less.
Further, it is preferable that a supercooled liquid region (ΔTx) obtained by difference between crystallization temperature Tx and glass transition temperature Tg (crystallization temperature Tx−glass transition temperature Tg) is 85 K or more.
Further, it is preferable that plastic strain (εf) is 10% or more.
The present invention can provide a zirconium (Zr)-based metal glass alloy having high glass forming ability, high strength, high ductility, high corrosion resistance, high viscous workability, precision castability, and high brightness.
DETAILED DESCRIPTION OF THE INVENTIONThe Zr-based metal glass alloy of the present invention will be described in detail below.
The zirconium (Zr)-based metal glass alloy according to the present invention contains, in atomic %, 62% or more and 67% or less of zirconium (Zr), 1% or more and 5% or less of niobium (Nb), 0.5% or more and 2% or less of titanium (Ti), 12% or more and 15% or less of copper (Cu), 8% or more and 10% or less of nickel (Ni), and 7.5% or more and 8.5% or less of aluminum (Al), and therefore has a composition represented by Zr62-67Nb1-5Ti0.5-2Cu12-15Ni8-10Al7.5-8.5.
The Zr-based metal glass alloy of the present invention is obtained by melting the above-mentioned component metals and then cooling at a critical cooling rate or higher.
The Zr-based metal glass alloy of the present invention has superior characteristics of high glass forming ability, high strength, high ductility, high corrosion resistance, high viscous workability, precision castability, and high brightness. The component metal elements that constitute the Zr-based metal glass alloy of the present invention contribute to the above characteristics as a whole by being blended in the above-mentioned predetermined proportions.
The Zr-based metal glass alloy of the present invention preferably has a wide supercooled liquid region (temperature width thereof) (ΔTx) obtained as difference between crystallization start temperature (hereinafter, referred to as crystallization temperature) Tx and glass transition temperature Tg (crystallization temperature Tx−glass transition temperature Tg), which is 85 K or more. Therefore, the Zr-based metal glass alloy of the present invention has high glass forming ability and high viscous workability due to high stability of the supercooled liquid.
Here, the high glass forming ability refers that a glass phase is easily generated because the supercooled liquid region (ΔTx) is 85 K or more, which is wide. Also, having high viscous workability refers that the viscosity is 1013 Poise or less in the supercooled liquid region ΔTx between the glass transition temperature Tg and the crystallization temperature Tx, and it has a property of being processed like starch syrup.
Further, the Zr-based metal glass alloy of the present invention has a large plastic strain (εf), preferably 10% or more (εf≥10%). Therefore, the Zr-based metal glass alloy of the present invention is characterized by having high ductility.
Further, the Zr-based metal glass alloy of the present invention is also characterized by having high strength and high flexibility, for example, practically requiring an alloy strength of 1,500 MPa or more and a high elastic strain of about 2%.
Furthermore, the Zr-based metal glass alloy of the present invention is also characterized by having high brightness. Here, having high brightness refers that, in a metal glass, the atoms are uniformly mixed and arranged in a disordered manner, and crystal grain boundaries and crystal orientation differences in a crystal alloy are not included, and thus the surface becomes smooth at an atomic level, and consequently has properties of exhibiting precise casting reversal, high brilliance, and light reflectivity.
The main component metals of the Zr-based metal glass alloy of the present invention will be described.
Zr is an element serving as a base of a metal glass alloy, and as described above, its content needs to be 62% or more and 67% or less in atomic %. As a result, Zr has an effect of expanding the supercooled liquid region ΔTx, enhances the glass forming ability, facilitates formation of an amorphous phase, and also has an effect of exhibiting high ductility. It is also an element that imparts corrosion resistance to the alloy by forming an oxide film or a passive film in the air.
Cu has an effect of improving mechanical properties of the metal glass alloy. As described above, the Cu content needs to be 12% or more and 15% or less in atomic %. The reason is that when the Cu content is less than 12% or exceeds 15%, the supercooled liquid region ΔTx becomes narrow, the glass forming ability of the alloy decreases and it is not possible to increase the strength of the alloy to a strength practically required, for example, 1,500 MPa or more. Further, it is also because high strain characteristics of 15% or more cannot be obtained.
Al is an indispensable element for forming a metal glass alloy, and has an effect of further improving the corrosion resistance. As described above, the Al content is needs to be 7.5% or more and 8.5% or less in atomic %. The reason is that when the Al content is less than 7.5% or exceeds 8.5%, the supercooled liquid region ΔTx becomes narrow, and the glass forming ability of the alloy decreases. Also, it is because, when the Al content exceeds 8.5%, the plastic strain (εf) becomes small and the ductility decreases.
Ni has effects of expanding the supercooled liquid region ΔTx and enhancing the glass forming ability. As described above, the Ni content needs to be 8% or more and 10% or less in atomic %. The reason is that when the Ni content is less than 8% or exceeds 10%, the supercooled liquid region ΔTx becomes narrow, the glass forming ability of the alloy decreases, and a high strain of 15% or more is not obtained.
Nb has effects of expanding the supercooled liquid region ΔTx, enhancing the glass forming ability, and increasing mechanical strength and the corrosion resistance. As described above, the Nb content needs to be 1% or more and 5% or less in atomic %. The reason is that when the Nb content is less than 1% or exceeds 5%, the supercooled liquid region ΔTx becomes narrow, and the glass forming ability of the alloy decreases.
By coexisting with Nb, Ti has effects of expanding the supercooled liquid region ΔTx, enhancing the glass forming ability, and increasing the mechanical strength, ductility, and corrosion resistance. As described above, the Ti content needs to be 0.5% or more and 2% or less in atomic %. The reason is that when the Ti content is less than 0.5% or exceeds 2%, the supercooled liquid region ΔTx becomes narrow, and the glass forming ability of the alloy decreases.
The Zr-based metal glass alloy of the present invention has the above composition, but its novel characteristic is that coexistence of Nb and Ti is essential. Here, the sum of the contents of Nb and Ti (Nb+Ti) is preferably 5% or less in atomic %, and the ratio of the contents of Nb and Ti (Nb/Ti) is preferably 1.0 or more and 8.0 or less.
Therefore, in the Zr-based metal glass alloy of the present invention, it is characterized in that three elements of Zr, Nb, and Ti which are group IV, and group V transition metals in the periodic table are essential and the total amount of the three elements of Zr, Nb, and Ti is large, and the total amount of the three elements is preferably 65% or more and 70% or less (65% to 70%) in atomic %.
As described above, in the Zr-based metal glass alloy of the present invention, due to a synergistic effect that the three elements of Zr, Nb, and Ti are essential and are multi-component, and the total amount is 65 atomic % or more, the Al amount is 8.5 atomic % or less, and the like, preferable characteristics that the supercooled liquid region is 85 K or more and the plastic strain is 10% or more appear.
As a result, as described above, the Zr-based metal glass alloy of the present invention has a high glass forming ability and high ductility, and further has characteristics of high strength, high corrosion resistance, high viscous workability, precision castability, and high brightness, and additionally has characteristics that it is possible to reduce the weight of alloy, lower melting point, improve corrosion resistance, improve oxidation resistance, reduce material cost, and facilitate alloy preparation.
When producing the Zr-based metal glass alloy of the present invention, after melting nodules or powder of component metals to prepare a melt of a master alloy of the component metals, the melt of the master alloy needs to be cooled and solidified while maintaining the supercooled liquid state. As a method for cooling and producing the metal glass alloy, there are a copper mold differential pressure casting method, an injection casting method, a forging casting method, a tightening casting method, a tilt casting method, a casting mold solution jetting method, and the like.
Therefore, after preparing the master alloy from the component metals of the above-mentioned content by an arc melting method or the like, the Zr-based metal glass alloy of the present invention can be prepared as a cylindrical rod material with a diameter of 2 to 5 mm or a plate material with a thickness of 2 to 4 mm, mainly by the copper mold differential pressure casting method, copper mold injection casting method, copper mold tightening casting method, copper mold tilt casting method, copper mold forging casting method, casting mold solution jetting method, or the like.
In arc melting, instead of melting by setting current to a constant value, for example, starting from initial 30% to 40% (current 100 A to 200 A) and gradually increasing current and voltage while controlling output. Both the voltage and the current change by adjusting the maximum current output during melting to 60 to 75% (current of about 300 A to 400 A), so as to be 40% to 60% (200 A to 300 A) at the end of melting, changing distance between a substance to be dissolved and a tip of electrode, and the like. Therefore, fluctuations in voltage and current from the initial state to the end of dissolution are, for example, a voltage of 20 V to 40 V and a current of 100 A to 400 A when a sample of 20 g is dissolved.
In other words, in the preparation of a master alloy by arc melting, a one-time total amount of component metals is set to a predetermined amount of, for example, 20 g, and arc melting under conditions of a voltage of 20 V to 40 V and a current of 100 A to 400 A under a reduced pressure argon gas atmosphere is repeated for at least 4 times or more to prepare a master alloy.
In the copper mold differential pressure casting method, as described in JP 08-109419 A, a metal material is provided on a water-cooled mold, and the metal material is melted by using the arc melting capable of rapidly melting the metal material, then the resulting molten metal is instantaneously cast into a vertical water-cooled mold provided below a lower part of the mold by utilizing gas differential pressure or gravity, and a moving speed of a molten metal is increased to obtain a large cooling rate to produce a large metal glass.
Moreover, in the copper mold tightening casting method, as described in JP 11-254196 A, a metal material is provided on a hearth, and the metal material is melted using a high energy heat source capable of melting the metal material, and then the obtained molten metal at a melting point or higher is pressed without superimposing cooling interfaces on each other to apply at least one of compressive stress and shear stress to the molten metal at a melting point or higher to be deformed into a desired shape. After or simultaneously with the deformation, the molten metal is cooled at a critical cooling rate or higher to produce a bulk metal glass of the desired shape.
Further, in the copper mold tilt casting method, as described in JP 2009-068101 A, an alloy material is melted in a melting furnace having an opened upper surface, and tilt casting is performed in which the molten alloy material, while being remelted, is tilted and injected into a forced cooling die having a cavity for molding, and at the same time, cooled under pressure with an upper punch that also serves as a cooling accelerator of a size that almost covers an upper surface of the molten metal in the cavity of the forced cooling die to produce metal glass.
Furthermore, in the casting mold solution jetting method, a master alloy sample melted in a quartz tube or a quartz crucible using a high-frequency coil connected to a high-frequency power source or the like is injected into the center of an injection port of a split copper mold for casting having an arbitrary shape such as a circle (φ1 mm to φ4 mm) or a corner utilizing a pressure of compressed gas (0.01 to 0.03 MPa). The molten master alloy sample moves to the copper mold at a high speed and is quenched and solidified, that is, cast into an amorphous structure.
A glass alloy structure of the Zr-based metal glass alloy of the present invention thus prepared can be confirmed by X-ray diffraction, optical microscope observation, transmission electron microscope observation, or the like.
Further, the plastic strain (εf) can be evaluated by measuring a compressive stress-strain curve using an Instron tester or an Instron type tester and using the curve.
Although the Zr-based metal glass alloy of the present invention has been described above in detail, the present invention is not limited to the above-described embodiments, and various improvements or modifications may be made without departing from the spirit of the present invention.
EXAMPLESHereinafter, examples of the Zr-based metal glass alloy according to the present invention will be specifically described, but the present invention is not limited to these examples.
Examples 1 to 10, Comparative Examples 1 to 7Powder of component metals of the content shown in Table 1 below was melted by arc melting while controlling output (voltage value and current value) from initial 20% to 45% at the end of melting to prepare a melt of master alloy. Thereafter, the melt was cooled and solidified while maintaining the supercooled liquid state, and a sample of the Zr-based metal glass alloy of a cylindrical rod material with a sample diameter of 2 mm (maximum diameter of 3 mm or more) was prepared, by a copper mold suction casting method, as described above.
Using each of these samples (alloy) thus prepared, an alloy structure was examined, and items of maximum diameter (mm), glass transition temperature Tg (K), crystallization temperature Tx (K), supercooled liquid region ΔTx (K), yield strength (MPa), fracture strength (MPa), and plastic strain εf (%) were measured and evaluated.
The results are shown in Table 1.
Here, the alloy structure was examined and confirmed by X-ray diffraction. In Table 1, the “glass phase” indicates a layer of only glass (amorphous), and the “mixed phase” indicates a mixed phase of glass (amorphous) and crystal.
Moreover, the supercooled liquid region ΔTx (K) was obtained as difference between crystallization temperature Tx and glass transition temperature Tg (crystallization temperature Tx−glass transition temperature Tg).
Further, the plastic strain εf was evaluated by measuring a compressive stress-strain curve using an Instron tester and using the curve.
In order to achieve the above object, the present invention develops and provides a zirconium (Zr)-based metal glass alloy containing, in atomic %, 62% or more and 67% or less of zirconium (Zr), 1% or more and 5% or less of niobium (Nb), 0.5% or more and 2% or less of titanium (Ti), 12% or more and 15% or less of copper (Cu), 8% or more and 10% or less of nickel (Ni), and 7.5% or more and 8.5% or less of aluminum (Al), and having a composition represented by Zr62-67Nb1-5Ti0.5-2Cu12-15Ni8-10Al7.5-8.5.
As shown in Table 1, it was confirmed that all the samples shown in Examples 1 to 10 in which the content of each element falls within the range of the present invention had a sample diameter of 2 mm and were large, with a maximum diameter of 3 mm or more or 4 mm or more, and the alloy structure was a glass layer.
Moreover, the supercooled liquid region ΔTx was 85 K or more in all the samples, and it was found that all the samples had high glass forming ability.
Further, the yield strength was 1,500 MPa or more in all the samples, and the fracture strength was 1,600 MPa or more in all the samples, and it was found that all the samples had high strength.
Furthermore, the plastic strain εf was 10% or more in all the samples, and it was found that all the samples had high ductility.
On the other hand, as shown in Table 1, Comparative Examples 1 to 7, which deviate from the scope of the present invention, could not obtain the effects of the present invention.
That is, in Comparative Examples 4 to 7, the alloy structure was a mixed phase of a glass layer and a crystal layer and was not a metal glass alloy. In Comparative Examples 4 to 7, the main constituent phase was crystal, clear glass transition temperature Tg and crystallization temperature Tx could not be detected, and the supercooled liquid region ΔTx could not be calculated.
Further, in all of Comparative Examples 1 to 7, the plastic strain εf was less than 10%, and it was found that the ductility was low.
From the above, the effect of the present invention is clear.
The Zr-based metal glass alloy of the present invention can be applied to applications such as electromagnetic equipment frames, spring materials, pin materials, gear materials, sensor materials, mirror materials, sensor materials, watch cases, watch dials, clock hands, optical element materials, and blades.
Claims
1. A zirconium-based metal glass alloy comprising, in atomic %, 62% or more and 67% or less of zirconium (Zr), 1% or more and 5% or less of niobium (Nb), 0.5% or more and 2% or less of titanium (Ti), 12% or more and 15% or less of copper (Cu), 8% or more and 10% or less of nickel (Ni), and 7.5% or more and 8.5% or less of aluminum (Al), the zirconium-based metal glass alloy having a composition represented by Zr62-67Nb1-5Ti0.5-2Cu12-15Ni8-10Al7.5-8.5.
2. The zirconium-based metal glass alloy according to claim 1, wherein the total sum of the contents of Zr, Nb, and Ti (Zr+Nb+Ti) in atomic % is 65% or more and 70% or less.
3. The zirconium-based metal glass alloy according to claim 1, wherein the sum of the contents of Nb and Ti (Nb+Ti) in atomic % is 5% or less, and the ratio of the contents of Nb and Ti (Nb/Ti) is 1.0 or more and 8.0 or less.
4. The zirconium-based metal glass alloy according to claim 1, wherein a supercooled liquid region (ΔTx) obtained by difference between crystallization temperature Tx and glass transition temperature Tg (crystallization temperature Tx−glass transition temperature Tg) is 85 K or more.
5. The zirconium-based metal glass alloy according to claim 1, wherein plastic strain (εf) is 10% or more.
6. The zirconium-based metal glass alloy according to claim 2, wherein the sum of the contents of Nb and Ti (Nb+Ti) in atomic % is 5% or less, and the ratio of the contents of Nb and Ti (Nb/Ti) is 1.0 or more and 8.0 or less.
7. The zirconium-based metal glass alloy according to claim 2, wherein a supercooled liquid region (ΔTx) obtained by difference between crystallization temperature Tx and glass transition temperature Tg (crystallization temperature Tx−glass transition temperature Tg) is 85 K or more.
8. The zirconium-based metal glass alloy according to claim 2, wherein plastic strain (εf) is 10% or more.
9. The zirconium-based metal glass alloy according to claim 3, wherein a supercooled liquid region (ΔTx) obtained by difference between crystallization temperature Tx and glass transition temperature Tg (crystallization temperature Tx−glass transition temperature Tg) is 85 K or more.
10. The zirconium-based metal glass alloy according to claim 3, wherein plastic strain (εf) is 10% or more.
11. The zirconium-based metal glass alloy according to claim 4, wherein plastic strain (εf) is 10% or more.
Type: Application
Filed: Dec 21, 2020
Publication Date: Dec 9, 2021
Inventors: Akihisa INOUE (Togane-shi Chiba-ken), Fanli KONG (Togane-shi Chiba-ken), Eiichi MAKABE (Sendai)
Application Number: 17/129,262
