This invention relates to continuous sheet casting of bulk-solidifying amorphous alloys, and, more particularly, to a method of continuous sheet casting amorphous alloy sheets having a large thickness.
Amorphous alloys have non-crystalline (amorphous) atomic structures generally formed by fast cooling the alloy from the molten liquid state to a solid state without the nucleation and growth of crystalline phases. As a result of the unique atomic structure produced during this process, amorphous alloys have high mechanical strength and good elasticity, while also exhibiting good corrosion resistance. Therefore, there is strong motivation in the materials field to find new applications for these materials in a variety of industries. However, because amorphous alloys require rapid cooling rates as they are solidified from temperatures above the melting state, it typically has only been possible to produce very thin ribbons or sheets of the alloys on a commercial scale, usually by a melt spin process wherein a stream of molten metal is rapidly quenched.
a and 1b show partial cross sectional schematic side views of a conventional continuous sheet casting apparatus. In a conventional continuous sheet casting process and apparatus 1, as shown in
As shown, in the detailed view in
Although it is possible to obtain quench rates at lower velocities, there are many difficulties that are encountered. For example, at typical melt viscosities and low wheel rotational speeds it is not possible to reliably sustain a continuous process. As a result, the melt may flow too fast through the orifice slit and spill over the wheel, precluding a stable melt puddle and a steady state moving solidification front. Although, some remedies can be implemented, such as reducing the orifice slit size, generally this is not a practical solution because the molten metal would erode the opening of such a small orifice very quickly. Despite these problems, an amorphous metal sheet having a sheet thickness ranging from 50 to 75 μm, and also retaining the mechanical properties of the amorphous alloys is disclosed in U.S. Pat. No. 6,103,396; however, the thickness range available for the disclosed process still leads to limitations in the types of applications in which such materials may be used.
Accordingly a need exists for a continuous process to cast thick sheets of bulk solidifying amorphous alloys.
The present invention is directed to a process and apparatus for continuous casting of amorphous alloy sheets having large sheet thickness using bulk solidifying amorphous alloys.
In one embodiment of the invention, the sheet is formed using conventional single roll, double roll, or other chill-body forms.
In another embodiment of the invention, the amorphous alloy sheets have sheet thicknesses of from 0.1 mm to 10 mm.
In one embodiment of the invention, the casting temperature is stabilized in a viscosity regime of 0.1 to 10,000 poise, preferably 1 to 1,000 poise, and more preferably 10 to 100 poise.
In one embodiment of the invention, the extraction of continuous sheet is preferably done at speeds of 0.1 to 50 cm/sec, and preferably 0.5 to 10 cm/sec, and more preferably of 1 to 5 cm/sec.
These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:
a is a side view in partial cross section of an exemplary conventional prior art apparatus for forming sheets of a molten metal.
b is a close-up of the formation of the sheet of molten metal shown in
The present invention is directed to a continuous casting process and apparatus for forming an amorphous alloy sheet having a large sheet thickness using a bulk solidifying amorphous alloy. The invention recognizes that it is possible to form a sheet of large thickness using bulk-solidifying amorphous alloys at high viscosity regimes.
For the purposes of this invention, the term amorphous means at least 50% by volume of the alloy is in amorphous atomic structure, and preferably at least 90% by volume of the alloy is in amorphous atomic structure, and most preferably at least 99% by volume of the alloy is in amorphous atomic structure.
Bulk solidifying amorphous alloys are a recently discovered family of amorphous alloys, which can be cooled at substantially lower cooling rates, of about 500 K/sec or less, and substantially retain their amorphous atomic structure. As such, they can be produced in thicknesses of 1.0 mm or more, substantially thicker than conventional amorphous alloys, which are typically limited to thicknesses of 0.020 mm, and which require cooling rates of 105 K/sec or more. U.S. Pat. Nos. 5,288,344; 5,368,659; 5,618,359; and 5,735,975, the disclosures of which are incorporated herein by reference in their entirety, disclose such bulk solidifying amorphous alloys.
One exemplary family of bulk solidifying amorphous alloys can be described as (Zr,Ti)a(Ni,Cu,Fe)b(Be,Al,Si,B)c, where a is in the range of from 30 to 75, b is in the range of from 5 to 60, and c in the range of from 0 to 50 in atomic percentages. Furthermore, these basic alloys can accommodate substantial amounts (up to 20% atomic, and more) of other transition metals, such as Hf, Ta, Mo, Nb, Cr, V, Co. A preferable alloy family is (Zr,Ti)a(Ni,Cu)b(Be)c, where a is in the range of from 40 to 75, b is in the range of from 5 to 50, and c in the range of from 5 to 50 in atomic percentages. Still, a more preferable composition is (Zr,Ti)a(Ni,Cu)b(Be)c, where a is in the range of from 45 to 65, b is in the range of from 7.5 to 35, and c in the range of from 10 to 37.5 in atomic percentages. Another preferable alloy family is (Zr)a(Nb,Ti)b(Ni,Cu)c(Al)d, where a is in the range of from 45 to 65, b is in the range of from 0 to 10, c is in the range of from 20 to 40 and d in the range of from 7.5 to 15 in atomic percentages.
Another set of bulk-solidifying amorphous alloys are ferrous metals (Fe, Ni, Co) based compositions, where the ferrous metal content is more than 50% by weight. Examples of such compositions are disclosed in U.S. Pat. No. 6,325,868 and in publications to (A. Inoue et. al., Appl. Phys. Lett., Volume 71, p 464 (1997)), (Shen et. al., Mater. Trans., JIM, Volume 42, p 2136 (2001)), and Japanese patent application 2000126277 (Publ. # 2001303218 A), all of which are incorporated herein by reference. One exemplary composition of such alloys is Fe72Al5Ga2P11C6B4. Another exemplary composition of such alloys is Fe72Al7Zr10Mo5W2B15. Although, these alloy compositions are not processable to the degree of the Zr-base alloy systems, they can still be processed in thicknesses of 1.0 mm or more, sufficient enough to be utilized in the current invention.
In general, crystalline precipitates in bulk amorphous alloys are highly detrimental to the properties of amorphous alloys, especially to the toughness and strength of these alloys, and as such it is generally preferred to minimize the volume fraction of these precipitates. However, there are cases in which, ductile crystalline phases precipitate in-situ during the processing of bulk amorphous alloys, which are indeed beneficial to the properties of bulk amorphous alloys, especially to the toughness and ductility of the alloys. Such bulk amorphous alloys comprising such beneficial precipitates are also included in the current invention. One exemplary case is disclosed in (C. C. Hays et. al, Physical Review Letters, Vol. 84, p 2901, 2000), the disclosure of which is incorporated herein by reference.
As discussed above, in one embodiment the present invention is directed to an apparatus for forming amorphous alloy sheets having large thicknesses of from 0.1 mm to 10 mm and having good ductility. In such an embodiment the sheet may be formed using a conventional single roll, double roll or other chill-body forms. Schematic diagrams of such conventional single roll apparatus are provided in
As shown in these diagrams, the continuous casting apparatus has a chill body 7 which moves relative to a injection orifice 3, through which the melt 19 is introduced. In this specification, the apparatus is described with reference to the section of a casting wheel 7 which is located at the wheel's periphery and serves as a quench substrate as used in the prior art. It will be appreciated that the principles of the invention are also applicable, as well, to other conventional quench substrate configurations such as a belt, double-roll wheels, wheels having shape and structure different from those of a wheel, or to casting wheel configurations in which the section that serves as a quench substrate is located on the face of the wheel or another portion of the wheel other than the wheel's periphery. In addition, it should be understood that the invention is also directed to apparatuses that quench the molten alloy by other mechanisms, such as by providing a flow of coolant fluid through axial conduits lying near the quench substrate.
In
The casting wheel quench substrate 27 may be comprised of copper or any other metal or alloy having relatively high thermal conductivity. Preferred materials of construction for the substrate 27 include fine, uniform grain-sized precipitation hardening copper alloys such as chromium copper or beryllium copper, dispersion hardening alloys, and oxygen-free copper. If desired, the substrate 27 may be highly polished or chrome-plated, or the like to obtain a sheet having smooth surface characteristics.
To provide additional protection against erosion, corrosion or thermal fatigue, the surface of the casting wheel may be coated in a conventional way using a suitably resistant or high-melt coating. For example, a ceramic coating or a coating of a corrosion-resistant, high-melting temperature metal may be applied provided that the wettability of the molten metal or alloy being cast on the chill surface is adequate.
The present invention is also directed to a processing method for making continuous amorphous alloy sheets with large thickness from bulk-solidifying amorphous alloys. A flow chart of this general process is shown in
As described above, in a first processing step a charge of the bulk solidifying amorphous alloy is provided. Viscosity and temperature processing parameters for an exemplary bulk solidifying amorphous alloy are provided in
Even though there is no liquid/crystallization transformation for a bulk solidifying amorphous metal, a “melting temperature” Tm may be defined as the thermodynamic liquidus temperature of the corresponding crystalline phase. Under this regime, the viscosity of bulk-solidifying amorphous alloys at the melting temperature lay in the range of about 0.1 poise to about 10,000 poise, which is to be contrasted with the behavior of other types of amorphous metals that have the viscosities at the melting temperature under 0.01 poise. In addition, higher values of viscosity can be obtained for bulk solidifying amorphous alloys by undercooling the alloy below the melting temperature, whereas ordinary amorphous alloys will tend to crystallize rather rapidly when undercooled.
In accordance with
Using the TTT and viscosity-temperature measurements shown in
After the alloy is ejected onto the chill body, the charge of amorphous alloy on the surface of chill body is cooled to temperatures below the glass transition temperature at a rate such that the amorphous alloy retains the amorphous state upon cooling. Preferably, the cooling rate is less than 1000° C. per second, but is sufficiently high to retain the amorphous state in the bulk solidifying amorphous alloy upon cooling. Once the lowest cooling rate that will achieve the desired amorphous structure in the article is chosen it can be engineered using the design of the chill body and the cooling channels. It should be understood that although several exemplary cooling rates are disclosed herein, the value of the cooling rate for any specific alloy cannot be specified herein as a fixed numerical value, because that value varies depending on the metal compositions, materials, and the shape and thickness of the sheet being formed. However, the value can be determined for each case using conventional heat flow calculations.
Accordingly, for bulk solidifying amorphous alloys, it is possible to reliably continue to process sheets even at low wheel rotational speeds by employing a high viscosity regime, so that the melt does not spill over the wheel, allowing for the formation of sheets with thicknesses up to about 10 mm.
Although specific embodiments are disclosed herein, it is expected that persons skilled in the art can and will design alternative continuous sheet casting apparatuses and methods to produce continuous amorphous alloy sheets that are within the scope of the following claims either literally or under the Doctrine of Equivalents.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/US2004/011559 | 4/14/2004 | WO | 00 | 6/21/2006 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2004/092428 | 10/28/2004 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
2190611 | Sembdner | Feb 1940 | A |
3989517 | Tanner et al. | Nov 1976 | A |
4050931 | Tanner et al. | Sep 1977 | A |
4064757 | Hasegawa | Dec 1977 | A |
4067732 | Ray | Jan 1978 | A |
4099961 | Patten | Jul 1978 | A |
4113478 | Tanner et al. | Sep 1978 | A |
4116682 | Polk et al. | Sep 1978 | A |
4116687 | Hasegawa | Sep 1978 | A |
4126449 | Tanner et al. | Nov 1978 | A |
4135924 | Tanner et al. | Jan 1979 | A |
4148669 | Tanner et al. | Apr 1979 | A |
4157327 | Martin et al. | Jun 1979 | A |
4289009 | Festag et al. | Sep 1981 | A |
4472955 | Nakamura et al. | Sep 1984 | A |
4478918 | Ueno et al. | Oct 1984 | A |
4621031 | Scruggs | Nov 1986 | A |
4623387 | Masumoto et al. | Nov 1986 | A |
4648437 | Pryor et al. | Mar 1987 | A |
4648609 | Deike | Mar 1987 | A |
4710235 | Scruggs | Dec 1987 | A |
4721154 | Christ et al. | Jan 1988 | A |
4743513 | Scruggs | May 1988 | A |
4768458 | Arakawa et al. | Sep 1988 | A |
4791979 | Liebermann | Dec 1988 | A |
4854370 | Nakamura | Aug 1989 | A |
4976417 | Smith | Dec 1990 | A |
4978590 | Granata, Jr. et al. | Dec 1990 | A |
4987033 | Abkowitz et al. | Jan 1991 | A |
4990198 | Masumoto et al. | Feb 1991 | A |
5032196 | Masumoto et al. | Jul 1991 | A |
5053084 | Masumoto et al. | Oct 1991 | A |
5053085 | Masumoto et al. | Oct 1991 | A |
5074935 | Masumoto et al. | Dec 1991 | A |
5117894 | Katahira | Jun 1992 | A |
5131279 | Lang et al. | Jul 1992 | A |
5169282 | Ueda et al. | Dec 1992 | A |
5213148 | Masumoto et al. | May 1993 | A |
5225004 | O'Handley et al. | Jul 1993 | A |
5250124 | Yamaguchi et al. | Oct 1993 | A |
5279349 | Horimura | Jan 1994 | A |
5288344 | Peker et al. | Feb 1994 | A |
5296059 | Masumoto et al. | Mar 1994 | A |
5302471 | Ito et al. | Apr 1994 | A |
5306463 | Horimura | Apr 1994 | A |
5312495 | Masumoto et al. | May 1994 | A |
5324368 | Masumoto et al. | Jun 1994 | A |
5368659 | Peker et al. | Nov 1994 | A |
5380375 | Hashimoto et al. | Jan 1995 | A |
5384203 | Apfel | Jan 1995 | A |
5390724 | Yamauchi et al. | Feb 1995 | A |
5449425 | Renard et al. | Sep 1995 | A |
5482580 | Scruggs et al. | Jan 1996 | A |
5567251 | Peker et al. | Oct 1996 | A |
5589012 | Hobby et al. | Dec 1996 | A |
5618359 | Lin et al. | Apr 1997 | A |
5634989 | Hashimoto et al. | Jun 1997 | A |
5647921 | Odagawa et al. | Jul 1997 | A |
5711363 | Scruggs et al. | Jan 1998 | A |
5735975 | Lin et al. | Apr 1998 | A |
5797443 | Lin et al. | Aug 1998 | A |
5886254 | Chi | Mar 1999 | A |
5950704 | Johnson et al. | Sep 1999 | A |
6021840 | Colvin | Feb 2000 | A |
6027586 | Masumoto et al. | Feb 2000 | A |
6044893 | Taniguchi et al. | Apr 2000 | A |
6200685 | Davidson | Mar 2001 | B1 |
6203936 | Cisar et al. | Mar 2001 | B1 |
6258183 | Onuki et al. | Jul 2001 | B1 |
6306228 | Inoue et al. | Oct 2001 | B1 |
6325868 | Kim et al. | Dec 2001 | B1 |
6371195 | Onuki et al. | Apr 2002 | B1 |
6376091 | Croopnick | Apr 2002 | B1 |
6408734 | Cohen | Jun 2002 | B1 |
6446558 | Peker et al. | Sep 2002 | B1 |
6491592 | Cackett et al. | Dec 2002 | B2 |
6771490 | Peker et al. | Aug 2004 | B2 |
6843496 | Peker et al. | Jan 2005 | B2 |
6887586 | Peker et al. | May 2005 | B2 |
20010052406 | Kubota et al. | Dec 2001 | A1 |
20020036034 | Xing et al. | Mar 2002 | A1 |
20020050310 | Kundig et al. | May 2002 | A1 |
20020187379 | Yasuo et al. | Dec 2002 | A1 |
20030222122 | Johnson et al. | Dec 2003 | A1 |
Number | Date | Country |
---|---|---|
2236325 | Apr 1991 | GB |
359013056 | Jan 1984 | JP |
61238423 | Oct 1986 | JP |
06-264200 | Sep 1994 | JP |
2000-256811 | Sep 2000 | JP |
02000277127 | Oct 2000 | JP |
2001303218 | Oct 2001 | JP |
02001303218 | Oct 2001 | JP |
Number | Date | Country | |
---|---|---|---|
20060260782 A1 | Nov 2006 | US |