Bulk nickel—silicon—boron glasses bearing iron

Abstract

NiFeSiB and NiFeSiBP metallic glass forming alloys and metallic glasses are provided. Metallic glass rods with diameters of at least one, up to three millimeters, or more can be formed from the disclosed alloys. The disclosed metallic glasses demonstrate high yield strength combined with high corrosion resistance, while for a relatively high Fe contents the metallic glasses are ferromagnetic.

Claims

1. An alloy comprising Fe in atomic percent a between 5 and 50, Si in atomic percent b between 10 and 14, B in atomic percent c between 9 and 13, the balance is Ni, and wherein the alloy is capable of forming a metallic glass rod having a diameter of at least 1 mm.

2. The alloy of claim 1, wherein the Fe atomic percent a is between 15 and 50, and the diameter of the metallic glass rod that can be formed is at least 1 mm.

3. The alloy of claim 1, wherein the Fe atomic percent a is between 25 and 40, and the diameter of the metallic glass rod that can be formed is at least 2 mm.

4. The alloy of claim 1, wherein a combined atomic percent of Si and B is between 21 and 24.

5. The alloy of claim 1, wherein up to 3 atomic % of Ni or Fe is substituted by Cr.

6. The alloy of claim 1, wherein up to 1.5 atomic % of Fe or Ni is substituted by Co, Mn, W, Mo, Ru, Re, Cu, Pd, Pt, Nb, V, Ta, or a combination thereof.

7. A metallic glass comprising the alloy of claim 1.

8. An alloy comprising composition selected from a group consisting of Ni.sub.52Fe.sub.25Si.sub.12B.sub.11, Ni.sub.47Fe.sub.30Si.sub.12B.sub.11, Ni.sub.44.5Fe.sub.32.5Si.sub.12B.sub.11, Ni.sub.42Fe.sub.35Si.sub.12B.sub.11, Ni.sub.39.5Fe.sub.37.5Si.sub.12B.sub.11, Ni.sub.37Fe.sub.40Si.sub.12B.sub.11, Ni.sub.53Fe.sub.25Si.sub.8B.sub.10P.sub.4, Ni.sub.53Fe.sub.25Si.sub.8B.sub.9P.sub.5, Ni.sub.53Fe.sub.25Si.sub.9B.sub.9P.sub.4, Ni.sub.53Fe.sub.25Si.sub.7B.sub.9P.sub.6, Ni.sub.53Fe.sub.25Si.sub.7B.sub.10P.sub.5, Ni.sub.53.68Fe.sub.25.32Si.sub.7.64B.sub.8.59P.sub.4.77, Ni.sub.52.32Fe.sub.24.68Si.sub.8.36B.sub.9.41P.sub.5.23, Ni.sub.54Fe.sub.24Si.sub.8B.sub.9P.sub.5, and Ni.sub.52Fe.sub.26Si.sub.8B.sub.9P.sub.5, wherein the alloy is capable of forming a metallic glass rod having a diameter of at least 1 mm.

9. An alloy comprising Fe in atomic percent a between 5 and 50, Si in atomic percent b between 7 and 10, B in atomic percent c between 7 and 10, and P in atomic percent d between 0.5 and 8, the balance is Ni, and wherein the alloy is capable of forming a metallic glass rod having a diameter of at least 1 mm.

10. The alloy of claim 9, wherein a is between 20 and 45, and the diameter of the metallic glass rod that can be formed when processed by water quenching a high temperature melt in a quartz tube having wall thickness of 0.5 mm is at least 2 mm.

11. The alloy of claim 9, wherein a combined atomic percent of Si B and P is between 21 and 23.

12. The alloy of claim 9, wherein up to 3 atomic % of Ni or Fe is substituted by Cr.

13. The alloy of claim 9, wherein up to 1.5 atomic % of Fe or Ni is substituted by Co, Mn, W, Mo, Ru, Re, Cu, Pd, Pt, Nb, V, Ta, or a combination thereof.

14. A metallic glass comprising the alloy of claim 9.

15. A method of producing the metallic glass of claim 14 comprising: melting the alloy into a molten state; and quenching the melt at a cooling rate sufficiently rapid to prevent crystallization of the alloy.

16. The method of claim 15, further comprising fluxing the melt with a reducing agent prior to quenching.

17. The method of claim 16, wherein the reducing agent is boron oxide.

18. The method of claim 15, the step of melting the alloy comprises melting the alloy in a crucible, the crucible made of fused silica, a ceramic, alumina, zirconia, or graphite, or in a water-cooled hearth made of copper or silver.

19. The method of claim 15, the step of quenching the melt comprises quenching a crucible containing the molten alloy in a bath of room temperature water, iced water, or oil.

20. The method of claim 15, the step of quenching the melt comprises injecting or pouring the molten alloy into a metal mold.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The description will be more fully understood with reference to the following figures, which are presented as various embodiments of the disclosure and should not be construed as a complete recitation of the scope of the disclosure. It is noted that, for purposes of illustrative clarity, certain elements in various drawings may not be drawn to scale.

(2) FIG. 1 provides a data plot showing the effect of Fe atomic concentration on the glass forming ability (GFA) of the NiFeSiB and NiFeSiBP alloys in accordance with embodiments of the disclosure.

(3) FIG. 2 provides calorimetry scans for example metallic glasses NiFeSiB from Table 1 with varying Fe atomic concentration in accordance with embodiments of the disclosure. Arrows from left to right designate the glass transition and liquidus temperatures, respectively.

(4) FIG. 3 provides an image of an amorphous 3 mm rod of example metallic glass Ni.sub.53Fe.sub.25Si.sub.8B.sub.9P.sub.5 in accordance with embodiments of the disclosure.

(5) FIG. 4 provides an X-ray diffractogram verifying the amorphous structure of a 3 mm rod of example metallic glass Ni.sub.53Fe.sub.25Si.sub.8B.sub.9P.sub.5 in accordance with embodiments of the disclosure.

(6) FIG. 5 provides data plots showing the effect of substituting B by P on the GFA of NiFeSiBP alloys according to the formula Ni.sub.53Fe.sub.25Si.sub.8B.sub.14-xP.sub.x, where the atomic percent x ranges from 4 to 6 in accordance with embodiments of the disclosure.

(7) FIG. 6 provides data plots showing the effect of substituting Si by P on the GFA of the NiFeSiBP alloys according to the formula Ni.sub.53Fe.sub.25Si.sub.13-xB.sub.9P.sub.x, where the atomic percent x ranges from 4 to 6 in accordance with embodiments of the disclosure.

(8) FIG. 7 provides data plots showing the effect of substituting B by Si on the GFA of the NiFeSiBP alloys according to the formula Ni.sub.53Fe.sub.25Si.sub.xB.sub.17-xP.sub.5, where the atomic percent x ranges from 7 to 9 in accordance with embodiments of the disclosure.

(9) FIG. 8 provides data plots showing the effect of varying the total metalloid content at the expense of the total metal content on the GFA of the NiFeSiBP alloys according to the formula (Ni.sub.0.679Fe.sub.0.321).sub.100-x(Si.sub.0.364B.sub.0.409P.sub.0.227).sub.x, where the total metalloid atomic percent x ranges from 21 to 23 in accordance with embodiments of the disclosure.

(10) FIG. 9 provides data plots showing the effect of substituting Ni by Fe on the GFA of the NiFeSiBP alloys according to the formula Ni.sub.78-xFe.sub.xSi.sub.8B.sub.9P.sub.5, where the Fe atomic percent x ranges from 24 to 26 in accordance with embodiments of the disclosure.

(11) FIG. 10 provides a compressive stress-strain diagram for example metallic glass Ni.sub.53Fe.sub.25Si.sub.9B.sub.8P.sub.5.

(12) FIG. 11 provides an image of a plastically bent 1 mm amorphous rod of example metallic glass Ni.sub.53Fe.sub.25Si.sub.8.5B.sub.9.5P.sub.4 in accordance with embodiments of the disclosure.

(13) FIG. 12 provides a plot of the corrosion depth versus time in 6M HCl solution of a 2 mm metallic glass rod having composition Ni.sub.53Fe.sub.25Si.sub.9B.sub.8P.sub.5.

DETAILED DESCRIPTION

(14) The present disclosure may be understood by reference to the following detailed description, taken in conjunction with the drawings as described herein.

(15) Description of Alloy Compositions

(16) In accordance with the provided disclosure and drawings, NiFeSiB and NiFeSiBP alloys are provided that surprisingly require very low cooling rates to form metallic glass. The alloys can form bulk metallic glasses having a lateral dimension of at least 1 mm. Specifically, by controlling the relative concentration of Fe to be from 15 to 50 atomic percent, the NiFeSiB and NiFeSiBP alloys can form metallic glass rods with diameters of at least 1 mm.

(17) In some embodiments, to further promote glass formation, the disclosure adds P in the NiFeSiB alloys. Specifically, an addition of P up to about 8% is shown to significantly improve glass forming ability.

(18) In some embodiments, the disclosure also demonstrates the substitution of Ni or Fe by Cr in NiFeSiB alloys.

(19) In various embodiments, the disclosure demonstrates that the process of fluxing prior to melt quenching improves the glass-forming ability. Fluxing is a chemical process by which the fluxing agent acts to reduce the oxide inclusions entrained in the glass-forming alloy that could potentially impair glass formation by catalyzing crystallization. Whether fluxing is beneficial in promoting glass formation can be determined by the composition of the alloy, the inclusion chemistry, and the fluxing agent chemistry. For the alloys claimed in the instant disclosure, fluxing with B.sub.2O.sub.3 was determined to dramatically improve bulk-glass formation. Fluxing NiFeSiB and NiFeSiBP alloys with B.sub.2O.sub.3 to improve glass forming ability has not been disclosed in either Masumoto or Chen.

(20) The disclosure provides alloys that have a good glass forming ability. The NiFeSiBP alloys capable of forming metallic glasses rods with diameters of at least 1 mm and up to 3 mm or larger, thereby show significantly better glass forming ability than the metallic glasses disclosed in JP-08-269647 by Masumoto et al. The alloys by Masumoto et al. were only capable of forming metallic wires with diameters of up to about 200 micrometers. The alloys and amorphous wires disclosed by Masumoto et al. contained Fe only optionally, so long as they don't impair the ability of the alloys to form amorphous wires of up to 200 micrometers in diameter. In various embodiments of the present disclosure, the addition of Fe between 15 and 50 at % in the disclosed range results in the improved GFA over the alloys and metallic glasses disclosed by Masumoto et al. In some embodiments, the presently disclosed alloys have a peak GFA around 30 at %.

(21) The glass-forming ability of each alloy in the disclosure was assessed by determining the maximum or critical rod diameter, defined as maximum rod diameter in which the amorphous phase can be formed when processed by the method of water quenching the molten alloy in quartz capillaries or tubes. Since quartz is known to be a poor heat conductor that retards heat transfer, the quartz thickness is a critical parameter associated with the glass-forming ability of the example alloys. Therefore, to quantify the glass-forming ability of each of the example alloys, the critical rod diameter, d.sub.c, is reported in conjunction with the associated quartz thickness, t.sub.w, of the capillary or tube used to process the alloy.

(22) A critical cooling rate, which is defined as the cooling rate required to avoid crystallization and form the amorphous phase of the alloy (i.e. the metallic glass) determines the critical rod diameter. The lower the critical cooling rate of an alloy, the larger its critical rod diameter. The critical cooling rate R.sub.c in K/s and critical rod diameter d.sub.c in mm are related via the following approximate empirical formula:
R.sub.c=1000/d.sub.c.sup.2Eq. (3)

(23) According to Eq. (3), the critical cooling rate for an alloy having a critical rod diameter of about 1 mm, as in the case of the alloys according to embodiments of the present disclosure, is only about 10.sup.3 K/s.

(24) Generally, three categories are known in the art for identifying the ability of a metal alloy to form glass (i.e. to bypass the stable crystal phase and form an amorphous phase). Metal alloys having critical cooling rates in excess of 10.sup.12 K/s are typically referred to as non-glass formers, as it is physically impossible to achieve such cooling rates over a meaningful thickness. Metal alloys having critical cooling rates in the range of 10.sup.5 to 10.sup.12 K/s are typically referred to as marginal glass formers, as they are able to form glass over thicknesses ranging from 1 to 100 micrometers according to Eq. (3). Metal alloys having critical cooling rates on the order of 10.sup.3 or less, and as low as 1 or 0.1 K/s, are typically referred to as bulk glass formers, as they are able to form glass over thicknesses ranging from 1 millimeter to several centimeters. The glass-forming ability of a metallic alloy is, to a very large extent, dependent on the combination and composition of the alloy. The combinational and compositional ranges of alloys capable of forming marginal glass formers are considerably broader than those for forming bulk glass formers.

(25) NiFeSiB and NiFeSiBP Alloys and Metallic Glasses

(26) In various embodiments, quartz capillaries with wall thicknesses roughly 10% of the tube diameter can be used to process the alloys.

(27) Specific embodiments of NiFeSiB alloys and metallic glasses that demonstrate the effect on GFA according to Eq. (1) are presented in Table 1. These alloys are processed in quartz capillaries with wall thicknesses roughly 10% of the tube inner diameter at 1250 C. Example alloys 1-15 have compositions according to Ni.sub.77-xFe.sub.xSi.sub.12B.sub.11, where the Fe atomic percent x varies between 0 and 45. The data shows that bulk-glass formation is possible over the disclosed range of Fe and Ni concentrations. A peak GFA at Fe composition 30 at. % is observed. At this peak GFA, a d.sub.cr value of 2.65 mm is obtained.

(28) TABLE-US-00001 TABLE 1 Example alloys according to Eq. (1) processed in quartz capillaries to form metallic glasses Example Composition [at %] d.sub.c [mm] t.sub.w [mm] 1 Ni.sub.77Si.sub.12B.sub.11 0.5 0.05 2 Ni.sub.74.5Fe.sub.2.5Si.sub.12B.sub.11 0.55 0.055 3 Ni.sub.72Fe.sub.5Si.sub.12B.sub.11 0.6 0.06 4 Ni.sub.67Fe.sub.10Si.sub.12B.sub.11 0.7 0.07 5 Ni.sub.62Fe.sub.15Si.sub.12B.sub.11 0.8 0.08 6 Ni.sub.57Fe.sub.20Si.sub.12B.sub.11 1.2 0.12 7 Ni.sub.54.5Fe.sub.22.5Si.sub.12B.sub.11 1.4 0.14 8 Ni.sub.52Fe.sub.25Si.sub.12B.sub.11 2.2 0.22 9 Ni.sub.47Fe.sub.30Si.sub.12B.sub.11 2.65 0.265 10 Ni.sub.44.5Fe.sub.32.5Si.sub.12B.sub.11 2.4 0.24 11 Ni.sub.42Fe.sub.35Si.sub.12B.sub.11 2.4 0.24 12 Ni.sub.39.5Fe.sub.37.5Si.sub.12B.sub.11 2.4 0.24 13 Ni.sub.37Fe.sub.40Si.sub.12B.sub.11 2.2 0.22 14 Ni.sub.34.5Fe.sub.42.5Si.sub.12B.sub.11 1.4 0.14 15 Ni.sub.32Fe.sub.45Si.sub.12B.sub.11 1.1 0.11

(29) NiFeSiBP alloys and metallic glasses demonstrating the effect on GFA of Ni by Fe Ni according to the formula given by Eq. (2) are presented in Table 2. These alloys are processed in quartz capillaries with wall thicknesses roughly 10% of the tube inner diameter at 1300 C. Example alloys 16-19 have compositions according to Ni.sub.77-xFe.sub.xSi.sub.8B.sub.11P.sub.4 where the Fe atomic percent x varies between 20 and 35. Compared to the NiFeSiB alloys presented in Table 1, in the embodiments presented in Table 2, 4 at % of Si is substituted by P such that the total of the metalloid content (Si+B+P) is 23.

(30) Like the disclosed NiFeSiB alloys, a peak in GFA at Fe concentration of 30 at. % is observed in the NiFeSiBP alloys, where a d.sub.cr value of 3 mm is obtained. Incorporating P in the NiFeSiB alloys as a substitution for Si improves GFA for the alloys of Eq. (2).

(31) TABLE-US-00002 TABLE 2 Example alloys according to Eq. (2) processed in quartz capillaries to form metallic glasses Example Composition [at %] d.sub.c [mm] t.sub.w [mm] 16 Ni.sub.57Fe.sub.20Si.sub.8B.sub.11P.sub.4 1.9 0.19 17 Ni.sub.52Fe.sub.25Si.sub.8B.sub.11P.sub.4 2.3 0.23 18 Ni.sub.47Fe.sub.30Si.sub.8B.sub.11P.sub.4 3.0 0.3 19 Ni.sub.42Fe.sub.35Si.sub.8B.sub.11P.sub.4 2.7 0.27

(32) FIG. 1 depicts a plot of the data of Table 1 and Table 2 that shows the effect of increasing the Fe atomic concentration NiFeSiB and NiFeSiBP alloys.

(33) When the Fe atomic percent a is between 25 and 40, NiFeSiB metallic glass rods with diameters of at least 2 mm can be formed. Metallic glass rods with diameters of at least 1 mm are formed when a is from about 5 to about 50. Alternatively, in various embodiments, metallic glass rods with diameters of at least 1 mm are formed when a is from about 15 to about 50. Alloys within the disclosed composition range demonstrate surprisingly higher glass forming ability than alloys with compositions outside the composition range.

(34) When a is between 20 and 30, NiFeSiBP metallic glass rods with diameters of at least 2 mm can be formed. Alternatively, when a is between 20 and 45, NiFeSiBP metallic glass rods with diameters of at least 2 mm can be formed. Metallic glass rods with diameters of at least 1 mm are formed over a range of a from about 5 to about 50. Alloys the disclosed composition range demonstrate surprisingly higher glass forming ability than alloys with compositions outside the Fe ranges disclosed herein.

(35) FIG. 2 provides calorimetry scans for NiFeSiB metallic glasses having compositions according to Ni.sub.77-xFe.sub.xSi.sub.12B.sub.11, as shown in Table 1 according to embodiments of the present disclosure. The arrows designate the liquidus temperatures of the alloys. Based on the calorimetry scans, the NiFeSiB alloys have lower liquidus temperatures as compared to those of the ternary NiSiB alloys. The scans show a reduction in the liquidus temperature near an Fe concentration of 30 at. %, with the minimum of just under 1000 C. occurring at an Fe concentration of 25 at. %. A lower liquidus temperature can imply a higher GFA. An increasing glass transition temperature with increasing Fe composition is also revealed. A higher glass-transition temperature can imply a higher GFA. The alloy with Fe composition of 30 at. % demonstrates the combination of low liquidus temperature and high glass-transition temperature.

(36) In various additional embodiments, quartz tubes with fixed wall thickness of 0.5 mm can be used to process various alloys. Example alloys 20-30 with compositions that satisfy the disclosed composition formula given by Eq. (2) are presented in Table 3. These alloys are processed in quartz tubes with 0.5 mm wall thickness at 1250 C. In particular, the alloy having the composition Ni.sub.53Fe.sub.25Si.sub.8B.sub.9P.sub.5 (Example 21) is a better glass former than other example alloys, as it is capable of forming metallic glass rods of up to 3 mm in diameter.

(37) An amorphous 3-mm rod of metallic glass Ni.sub.53Fe.sub.25Si.sub.8B.sub.9P.sub.5 is shown in FIG. 3, while the x-ray diffractogram verifying the amorphous structure of the metallic glass rod is shown in FIG. 4.

(38) TABLE-US-00003 TABLE 3 Example alloys according to Eq. (2) processed in quartz tubes to form metallic glasses Example Composition [at %] d.sub.c [mm] t.sub.w [mm] 20 Ni.sub.53Fe.sub.25Si.sub.8B.sub.10P.sub.4 2.0 0.5 21 Ni.sub.53Fe.sub.25Si.sub.8B.sub.9P.sub.5 3.0 0.5 22 Ni.sub.53Fe.sub.25Si.sub.8B.sub.8P.sub.6 1.0 0.5 23 Ni.sub.53Fe.sub.25Si.sub.9B.sub.9P.sub.4 2.0 0.5 24 Ni.sub.53Fe.sub.25Si.sub.7B.sub.9P.sub.6 2.0 0.5 25 Ni.sub.53Fe.sub.25Si.sub.7B.sub.10P.sub.5 2.0 0.5 26 Ni.sub.53Fe.sub.25Si.sub.9B.sub.8P.sub.5 1.0 0.5 27 Ni.sub.53.68Fe.sub.25.32Si.sub.7.64B.sub.8.59P.sub.4.77 2.0 0.5 28 Ni.sub.52.32Fe.sub.24.68Si.sub.8.36B.sub.9.41P.sub.5.23 2.0 0.5 29 Ni.sub.54Fe.sub.24Si.sub.8B.sub.9P.sub.5 2.5 0.5 30 Ni.sub.52Fe.sub.26Si.sub.8B.sub.9P.sub.5 2.5 0.5

(39) Example alloys 20-22 demonstrate the effect of varying the atomic concentration of P at the expense of B on the GFA of the NiFeSiBP alloys according to the formula Ni.sub.53Fe.sub.25Si.sub.8B.sub.14-xP.sub.x, where the P atomic percent x ranges from 4 to 6. A peak in the GFA occurs at a P concentration of 5 at %, associated with the formation of metallic glass rods of 3 mm in diameter. These results are presented graphically in FIG. 5.

(40) Example alloys 21, 23, and 24 demonstrate the effect of varying the atomic concentration of P at the expense of Si on the GFA of the NiFeSiBP alloys according to the formula Ni.sub.53Fe.sub.25Si.sub.13-xB.sub.9P.sub.x, where the P atomic percent x ranges from 4 to 6. These results are presented graphically in FIG. 6, which shows that the largest metallic glass rod of 3 mm in diameter can be formed at a P concentration of 5 at %.

(41) Example alloys 21, 25, and 26 demonstrate the effect of varying the atomic concentration of Si at the expense of B on the GFA of the NiFeSiBP alloys according to the formula Ni.sub.53Fe.sub.25Si.sub.xB.sub.17-xP.sub.5, where the Si atomic percent x ranges from 7 to 9. These results are presented graphically in FIG. 7, which shows that the largest metallic glass rod of 3 mm in diameter can be formed at a Si concentration of 8 at %.

(42) Example alloys 21, 27, and 28 demonstrate the effect of varying the total metalloid content at the expense of the total metal content on the GFA of the NiFeSiBP alloys according to the formula (Ni.sub.0.679Fe.sub.0.321).sub.100-x(Si.sub.0.364B.sub.0.409P.sub.0.227), where metalloid atomic percent x ranges from 21 to 23. FIG. 8 provides data plots showing the effect of varying the total metalloid content at the expense of the total metal content, on the GFA of the NiFeSiBP alloys. Alloys having the formula (Ni.sub.0.679Fe.sub.0.321).sub.100-x(Si.sub.0.364B.sub.0.409P.sub.0.227), where the total metalloid atomic percent x ranges from 21 to 23 in accordance with embodiments of the disclosure, can produce metallic glass rods having diameters of at least 2 mm. When the metalloid content is 22 at %, a metallic glass rod having a diameter of 3 mm can be formed. When a combined composition of Si, B and P (b+c+d) is between 21 and 23, NiFeSiBP metallic glass rods with diameters of at least 2 mm are formed

(43) Example alloys 21, 29, and 30 demonstrate the effect of varying the atomic concentration of Fe at the expense of Ni on the GFA of the NiFeSiBP alloys according to the formula Ni.sub.78-xFe.sub.xSi.sub.8B.sub.9P.sub.5, where atomic percent of Fe x ranges from 24 to 26. FIG. 9 provides data plots of these results. The plots point to x=25 as the Fe content at which the largest metallic glass rod of 3 mm in diameter could be formed.

(44) The effect of incorporating Cr as a replacement for Ni according to the formula Ni.sub.53-xFe.sub.25Cr.sub.xSi.sub.8B.sub.9P.sub.5, where the atomic percent of Cr x ranges from 0 to 4 is illustrated in example alloys 31-33 and Table 4. These alloys are processed in quartz capillaries at 1300 C. As shown, incorporating Cr in the NiFeSiBP alloys degrades the glass-forming ability slightly if the Cr atomic concentration is less than 3%. Specifically, the critical rod diameter d.sub.c reduces from 3 mm to 2.6 mm when Cr addition is 2 at %. Also, the glass forming ability degrades more drastically if the Cr atomic concentration is more than 3%. Specifically, the critical rod diameter d.sub.c reduces from 2.6 mm to below 1 mm when Cr addition is 4 at %. Therefore, the desirable Cr addition ranges from 0 to 3 at %.

(45) TABLE-US-00004 TABLE 4 Example alloys according to the formula Ni.sub.53xFe.sub.25Cr.sub.xSi.sub.8.5B.sub.9.5P.sub.4 processed in quartz capillaries to form metallic glasses Example Composition [at %] d.sub.c [mm] t.sub.w [mm] 31 Ni.sub.53Fe.sub.25Si.sub.8.5B.sub.9.5P.sub.4 3.0 0.3 32 Ni.sub.51Fe.sub.25Cr.sub.2Si.sub.8.5B.sub.9.5P.sub.4 2.6 0.26 33 Ni.sub.49Fe.sub.25Cr.sub.4Si.sub.8.5B.sub.9.5P.sub.4 <1.0 0.1

(46) The effect of fluxing the NiFeSiBP alloys with boron oxide on the GFA is also explored. As shown in Table 5, the alloy Ni.sub.53Fe.sub.25Si.sub.8B.sub.9P.sub.5 having the same composition, but being fluxed, had a d.sub.c of 3 mm. If the alloy is not fluxed with boron oxide, the critical rod diameter is less than 1 mm.

(47) TABLE-US-00005 TABLE 5 Effect of fluxing the alloys with boron oxide on GFA Example Composition [at %] Fluxing d.sub.c [mm] t.sub.w [mm] 21 Ni.sub.53Fe.sub.25Si.sub.8B.sub.9P.sub.5 Fluxed 3.0 0.5 21 Ni.sub.53Fe.sub.25Si.sub.8B.sub.9P.sub.5 Unfluxed <1 0.5

(48) The measured mechanical properties include compressive yield strength, notch toughness, and bending ductility.

(49) The compressive yield strength, .sub.y, is the measure of the material's ability to resist non-elastic yielding. The yield strength is the stress at which the material yields plastically. A high .sub.y ensures that the material will be strong. The compressive stress-strain diagram of example metallic glass Ni.sub.53Fe.sub.25Si.sub.9B.sub.8P.sub.5 is presented in FIG. 10. The compressive yield strength for this metallic glass is determined to be 2800 MPa. The compressive yield strength of all metallic glasses according to the current disclosure is expected to be over 2500 MPa.

(50) The stress intensity factor at crack initiation (i.e. the notch toughness), K.sub.q, is the measure of the material's ability to resist fracture in the presence of a notch. The notch toughness is a measure of the work required to propagate a crack originating from a notch. A high K.sub.q ensures that the material will be tough in the presence of defects. The notch toughness of example metallic glass Ni.sub.53Fe.sub.25Si.sub.9B.sub.8P.sub.5 is measured to be 28.51.5 MPa m.sup.1/2. The notch toughness of all metallic glasses according to the current disclosure is expected to be over 20 MPa m.sup.1/2.

(51) Bending ductility is a measure of the material's ability to deform plastically and resist fracture in bending in the absence of a notch or a pre-crack. A high bending ductility ensures that the material will be ductile in a bending overload. The metallic glasses NiFeSiB or NiFeSiBP were found to exhibit a remarkable bending ductility, as rods of the metallic glasses are capable of undergoing macroscopic plastic deformation under a bending load at diameters as large a 1 mm or larger. An image of a plastically bent 1 mm amorphous rod of example metallic glass Ni.sub.53Fe.sub.25Si.sub.8.5B.sub.9.5P.sub.4 is presented in FIG. 11.

(52) A plastic zone radius, r.sub.p, defined as K.sub.q.sup.2/.sub.y.sup.2, is a measure of the critical flaw size at which catastrophic fracture is promoted. The plastic zone radius determines the sensitivity of the material to flaws; a high r.sub.p designates a low sensitivity of the material to flaws. The notch plastic zone radius of example metallic glass Ni.sub.53Fe.sub.25Si.sub.9B.sub.8P.sub.5 is estimated to be 33 m. The plastic zone radius of all metallic glasses according to the current disclosure is expected to be over 10 m.

(53) The metallic glasses also exhibit good corrosion resistance. The corrosion resistance of example metallic glass Ni.sub.53Fe.sub.25Si.sub.9B.sub.8P.sub.5 has been evaluated by immersion test in 6M HCl. A plot of the corrosion depth versus time is presented in FIG. 12. The corrosion depth at approximately 924 hours is measured to be about 13 micrometers. The corrosion rate is estimated to be 0.125 mm/year. The corrosion rate of all metallic glasses according to the current disclosure is expected to be under 1 mm/year.

(54) Lastly, alloys containing Fe at atomic concentrations of at least about 20% are found to be magnetic. Bulk metallic glass cores made from such alloys therefore may be useful as ferromagnets for power electronics applications, with non-limiting applications selected from the group consisting of inductors, transformers, clutches, and DC/AC converters.

(55) Description of Methods of Forming Alloy Compositions and Metallic Glass Articles

(56) A particular method for producing the alloy ingots of the disclosure involves inductive melting of the appropriate amounts of elemental constituents in a fused silica crucible under inert atmosphere. Alternatively, the melting crucible may also be crystalline silica, a ceramic such as alumina or zirconia, graphite, or a water-cooled hearth made of copper or silver. Particular purity levels of the constituent elements were as follows: Ni 99.995%, Fe 99.95%, Cr 99.996%, Si 99.9999%, B 99.5%, and P 99.9999%.

(57) In some embodiments, prior to producing an amorphous article, the alloyed ingots can be fluxed with a reducing agent such as dehydrated boron oxide (B.sub.2O.sub.3) by re-melting the ingots in a quartz tube under inert atmosphere. The alloy melt is brought in contact with the boron oxide melt. The two melts to interact for a period of time, e.g. about 1000 s, at high temperature, e.g. between 1150 and 1350 C., under inert atmosphere. The mixture is quenched in a bath of room temperature water to form fluxed alloy ingots. In various alternate embodiments, the bath can be iced water or oil. The example alloys presented in the current disclosure have been fluxed according to the method described above.

(58) Various methods for producing metallic glass rods from the alloys of the disclosure include re-melting the fluxed alloy ingots in quartz capillaries or tubes in a furnace at high temperature, e.g. between 1150 and 1350 C. under high purity argon, and rapidly quenching in a room-temperature water bath. The wall thickness of the quartz tube can vary from 0.05 mm to 0.5 mm. The example alloys presented in the current disclosure were produced according to the method described above. The wall thickness of the quartz capillaries used were about 10% of the quartz inner diameter, while the wall thickness of the quartz tubes were 0.5 mm.

(59) Optionally, amorphous articles from the alloys of the disclosure can also be produced by re-melting the fluxed alloy ingots and injecting or pouring the molten alloy into a metal mold made for example of copper, brass, or steel.

(60) Test Methodology for Assessing Glass Forming Ability

(61) The glass-forming ability of each alloy was assessed by determining the maximum rod diameter in which the amorphous phase of the alloy (i.e. the metallic glass phase) could be formed when processed by the quartz water quenching method described above. X-ray diffraction with Cu-K radiation was performed to verify the amorphous structure of the alloys.

(62) Test Methodology for Differential Scanning Calorimetry

(63) Differential scanning calorimetry was performed on sample metallic glasses at a scan rate of 20 K/min to determine the glass-transition, crystallization, solidus, and liquidus temperatures of sample metallic glasses.

(64) Test Methodology for Measuring Notch Toughness

(65) The notch toughness of sample metallic glasses was determined on 2-mm diameter rods. The rods were notched using a wire saw with a root radius ranging from 0.10 to 0.13 m to a depth of approximately half the rod diameter. The notched specimens were placed on a 3-point bending fixture with span distance of 12.7 mm and carefully aligned with the notched side facing downward. The critical fracture load was measured by applying a monotonically increasing load at constant cross-head speed of 0.001 mm/s using a screw-driven testing frame. Two tests were performed, and the average value and associated variance are presented. The stress intensity factor for the geometrical configuration employed here was evaluated using the analysis by Murakimi (Y. Murakami, Stress Intensity Factors Handbook, Vol. 2, Oxford: Pergamon Press, p. 666 (1987)).

(66) Test Methodology for Measuring Compressive Yield Strength

(67) Compression testing of sample metallic glasses was performed on cylindrical specimens 2 mm in diameter and about 4 mm in length. A monotonically increasing load was applied at a constant cross-head speed of 0.001 mm/s using a screw-driven testing frame. The strain was measured using a linear variable differential transformer. The compressive yield strength was estimated as the maximum stress attained prior to failure.

(68) Test Methodology for Measuring Corrosion Resistance

(69) The corrosion resistance of sample metallic glasses was evaluated by immersion tests in hydrochloric acid (HCl). A rod of metallic glass sample with initial diameter of 1.91 mm, and a length of 16.13 mm was immersed in a bath of 6M HCl at room temperature. The density of the metallic glass rod was measured using the Archimedes method to be 7.64 g/cc. The corrosion depth at various stages during the immersion was estimated by measuring the mass change with an accuracy of 0.01 mg. The corrosion rate was estimated assuming linear kinetics.

(70) The disclosed NiFeSiB or NiFeSiBP alloys have good glass forming ability, along with very high strength and good corrosion resistance. The combination of high glass-forming ability and the mechanical and corrosion performance of the bulk NiFe based metallic alloys makes them excellent candidates for various engineering applications. Among these applications, the disclosed alloys can be used to form a bulk ferromagnetic core, which itself can be used for various applications, including but not limited to inductors, transformers, clutches, and DC/AC converters.

(71) Having described several embodiments, it will be recognized by those skilled in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the invention. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present invention. Accordingly, the above description should not be taken as limiting the scope of the invention.

(72) Those skilled in the art will appreciate that the presently disclosed embodiments teach by way of example and not by limitation. Therefore, the matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall therebetween.