CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Patent Application No. 61/710,964, entitled "Bulk Nickel-Phosphorus-Boron Glasses Bearing Molybdenum", filed on October 8, 2012, and U.S. Provisional Patent Application No. 61/847,955, entitled "Bulk Nickel-Phosphorus-Boron Glasses Bearing Molybdenum, Niobium and Manganese", filed on July 18, 2013, both of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

[0002] The present disclosure is directed to nickel-phosphorous-boron (Ni-P-B) alloys bearing molybdenum (Mo) and optionally niobium (Nb) capable of forming bulk glassy rods with diameters of 1 mm or greater. The present disclosure is also directed to Ni-P-B alloys bearing Mo, Nb, and Mn capable of forming bulk metallic glass rods with diameters of at least 1 .5 mm and as large as 3 mm or greater.

BACKGROUND

[0003] Bulk glass forming Ni ₈ o.5- _x A _x P _{1 6} .5B ₃ alloys, where element A is defined as the combination of Cr and Nb, have recently been disclosed in U.S. Patent Application No. 13/592,095, entitled "Bulk Nickel-Based Chromium and Phosphorous Bearing Metallic Glasses", filed on August 22, 2012. In those alloys, Cr ranges between 2 and 12 and Nb between 2 and 4. The alloys of the present disclosure are represented by the same compositional formula, but with A being instead a combination of Mo, Nb, and Mn, over approximately the same ranges.

[0004] Due to the attractive engineering properties of Ni-based P and B bearing bulk glasses, such as high strength, toughness, bending ductility, and corrosion resistance, it is desirable to develop other families of such alloys that incorporate different transition metals in order to explore the possibility of even better engineering performance. These and other needs are accomplished by the descriptions in the present disclosure.

BRIEF SUMMARY

[0005] This disclosure provides bulk glass forming Ni-Mo-Nb-P-B alloys capable of forming a bulk metallic glass rod with a diameter of 3 mm. Such bulk metallic glass rods can be formed when the molten alloy is processed by water quenching while contained in a fused silica tube having a wall thickness not larger than 0.3 mm.

[0006] This disclosure further provides Ni-Mo-Nb-P-B alloys that can include a small fraction of Mn. These alloys have better glass forming ability compared to the alloys free of Mn. Ni-Mo-Nb-Mn-P-B alloys are capable of forming metallic glass rods with diameters of at least 2 mm, and as large as 3 mm or larger when processed by melt water quenching in fused silica tubes having wall thickness of 0.5 mm. In addition, the metallic glasses have high yield strength and high notch toughness.

[0007] The disclosure is directed to an alloy or a metallic glass comprising an alloy represented by the following formula (subscripts denote atomic percent):

Ni(100-a-b-c-d)MoaNbbPcBd Equation (1 )

where:

a is between 2 and 12, c is between 14 and 19, and

d \s between 1 and 4.

[0008] In another embodiment, a + b is between 7 and 9.

[0009] In yet another embodiment, a is between 3 and 5 and b is between 3 and 5.

[0010] In yet another embodiment, c + d is between 18.5 and 20.5.

[0011] In yet another embodiment, c is between 16 and 17 and d \s between 2.75 and 3.75.

[0012] In yet another embodiment, up to 1 atomic % of P is substituted by Si.

[0013] In yet another embodiment, up to 2 atomic % of Mo is substituted by Fe, Co, Mn, W, Cr, Ru, Re, Cu, Pd, Pt, V, Ta, or combinations thereof.

[0014] In yet another embodiment, up to 2 atomic % of Ni is substituted by Fe, Co, Mn, W, Cr, Ru, Re, Cu, Pd, Pt, V, Ta, or combinations thereof.

[0015] In yet another embodiment, the alloys are capable of forming amorphous rods of diameter of at least 1 mm when rapidly quenched from the molten state.

[0016] In yet another embodiment, the melt of the alloy is fluxed with a reducing agent prior to rapid quenching.

[0017] In yet another embodiment, the temperature of the alloy melt prior to quenching is at least 100 degrees above the liquidus temperature of the alloy.

[0018] In yet another embodiment, the temperature of the alloy melt prior to quenching is at least 1 100 °C.

[0019] In yet another embodiment, rapid quenching is achieved by water-quenching a quartz tube containing the molten alloy.

[0020] In yet another embodiment, the thickness of the quartz-tube wall is between 0.1 and 0.5 mm.

[0021] In yet another embodiment, a wire made of the metallic glass having a diameter of 1 mm can undergo macroscopic plastic bending under load without fracturing

catastrophically. [0022] The disclosure is also directed to alloy or metallic glass Ni72.slvlO4Nb4Pi6.08B3.12, Ni72.3M08Pi 6.5B32, Ni72.3M04Nb4Pi6.5B32, Ni72.3M03.5Nb4.5Pi6.5B32, Ni72.3M04Nb4Pi6.2B35, Ni72.3M03Nb5Pi6.5B32, Ni72.3M04.5Nb3.5Pi6.5B32, Ni72.3M05Nb3Pi6.5B32, Ni72.3M04Nb4P17.2B25, and

[0023] In yet another embodiment, a method is provided for forming a metallic glass article. The method includes melting an alloy comprising at least Ni, Mo, P, and B and optionally Nb with a formula Ni ₍₁₀ o-a-t>-c-d ₎ lvlo _a Nb _b P _c B _£i , where an atomic percent of

molybdenum (Mo) a is between 2 and 12, an atomic percent of niobium (Nb) b is between 0 and 8, an atomic percent of phosphorus (P) c is between 14 and 19, an atomic percent of boron (B) d \s between 1 and 4, and the balance is nickel (Ni). The method also includes quenching the molten alloy at a cooling rate sufficiently rapid to prevent crystallization of the alloy.

[0024] The disclosure is directed to an alloy, or a metallic glass comprising an alloy, represented by the following formula (subscripts denote atomic percent):

Ni(100-a-b-c-d-e)MoaNbbMncPdBe Equation (2)

where:

a is between 1 and 5,

b is between 3 and 5,

c is up to 2,

d is between 16 and 17, and

e is between 2.75 and 3.75,

[0025] In some embodiments, the largest rod diameter of the metallic glass according to Eq. (2) that can be formed when processed by water quenching the high temperature melt in a fused silica tube having wall thickness of 0.5 mm is at least 1 .5 mm.

[0026] In another embodiment, a + c of the alloy or metallic glass according to Eq. (2) is between 3 and 5, while c is between 0.5 and 1 .5, and wherein the largest rod diameter that can be formed with an amorphous phase is at least 2 mm.

[0027] In another embodiment, a + c of the alloy or metallic glass according to Eq. (2) is between 3.5 and 4.5, while c is between 0.75 and 1 .25, and wherein the largest rod diameter that can be formed with an amorphous phase is at least 2.5 mm.

[0028] In yet another embodiment, up to 1 atomic percent of P of the alloy or metallic glass according to Eq. (2) is substituted by Si.

[0029] In yet another embodiment, up to 2 atomic percent of Ni of the alloy or metallic glass according to Eq. (2) is substituted by Fe, Co, W, Ru, Re, Cu, Pd, Pt, or combinations thereof.

[0030] In yet another embodiment, the melt of the alloy according to Eq. (2) is fluxed with a reducing agent prior to rapid quenching. [0031] In yet another embodiment, the temperature of the alloy melt according to Eq. (2) prior to quenching is at least 200 °C above the liquidus temperature.

[0032] In yet another embodiment, the temperature of the alloy melt according to Eq. (2) prior to quenching is at least 1200°C.

[0033] In yet another embodiment, the compressive yield strength of the metallic glass according to Eq. (2) is at least 2200 MPa.

[0034] In yet another embodiment, the stress intensity at crack initiation (i.e. the notch toughness) of the metallic glass according to Eq. (2) when measured on a 2 mm diameter rod containing a notch with length between 0.75 and 1 .25 mm and root radius between 0.1 and 0.15 mm is at least 60 MPa m ^{1 2} .

[0035] In yet another embodiment, a wire made of such metallic glass according to Eq. (2) having a diameter of 1 mm can undergo macroscopic plastic deformation under bending load without fracturing catastrophically.

[0036] The disclosure is also directed to an alloy, or a metallic glass comprising an alloy, selected from Ni72.3Mo3.5Nb4Mno.5Pi6.5B32, Ni ₇ 2.3Mo3Nb4Mn ₁ P ₁₆ .5B ₃ .2, and

Ni72.3M02.5Nb4MnL5Pi6.5B32.

[0037] Additional embodiments and features are set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by the practice of the invention. A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings, which forms a part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The description will be more fully understood with reference to the following figures and data graphs, which are presented as various embodiments of the disclosure and should not be construed as a complete recitation of the scope of the disclosure, wherein:

[0039] FIG. 1 provides a data graph showing the effect of Mo atomic concentration on the glass forming ability of the Ni-Mo-P-B alloys.

[0040] FIG. 2 provides a data graph showing calorimetry scans for sample Ni-Mo-P-B metallic glasses from Table 1 with varying Mo atomic concentration (Arrows from left to right designate the glass-transition and liquidus temperatures).

[0041] FIG. 3 provides a data graph showing the effect of Nb atomic concentration on the glass forming ability of the Ni-Mo-Nb-P-B alloys.

[0042] FIG. 4 provides an X-ray diffractogram verifying the amorphous structure of a 2.9 mm rod of sample metallic glass Ni ₇₂ . ₃ M0 ₄ Nb ₄ Pi ₆ . ₅ B _{3 2} . [0043] FIG. 5 provides a data graph showing calorimetry scans for sample Ni-Mo-Nb-P-B metallic glasses with varying Nb atomic concentration. Arrows designate the liquidus temperatures.

[0044] FIG. 6 provides a data graph showing the effect of B atomic concentration on the glass forming ability of the Ni-Mo-Nb-P-B alloys.

[0045] FIG. 7 provides a data graph showing the calorimetry scans for sample Ni-Mo-Nb- P-B metallic glasses with varying B atomic concentration. Arrows designate the liquidus temperatures.

[0046] FIG. 8 provides a data graph showing the effect of metalloid atomic concentration on the glass forming ability of the Ni-Mo-Nb-P-B alloys.

[0047] FIG. 9 provides an image showing a plastically bent 1 mm amorphous rod of sample metallic glass N i72.3M05Nb3Pi6.5B3 2.

[0048] FIG. 10 provides a plot showing the effect of substituting Mo by Mn on the glass forming ability of alloy Ni _72.3 Mo ₄ -xNb ₄ Mn _x P _16.5 B ₃ .2.

[0049] FIG. 1 1 provides a plot showing calorimetry scans for sample metallic glass Ni _72.3 Mo ₄ -xNb ₄ Mn _x P _16.5 B ₃ .2. Arrows from left to right designate the glass-transition and liquidus temperatures, respectively.

[0050] FIG. 12 provides an optical image of an amorphous 3 mm rod of example metallic glass Ni72.3Mo3Nb ₄ Mn ₁ P ₁₆ .5B3.2.

[0051 ] FIG. 13 provides an X-ray diffractogram verifying the amorphous structure of a 3 mm rod of example metallic glass Ni _72.3 Mo ₃ Nb ₄ Mn ₁ P _16.5 B ₃ .2.

[0052] FIG. 14 provides a compressive stress-strain diagram for sample metallic glass

Ni72. ₃ Mo ₃ Nb4Mn ₁ P ₁₆ .5B3.2.

[0053] FIG. 15 provides an optical image of a plastically bent 1 mm metallic glass rod of sample metallic glass Ni7 ₂ .3Mo ₃ Nb ₄ Mn ₁ P ₁₆ .5B3.2.

[0054] FIG. 16 provides a plot showing the corrosion depth versus time in 6M HCI solution of a 2 mm metallic glass rod having composition Ni _72.3 Mo ₃ Nb ₄ Mn ₁ P _{16 5} B ₃ 2.

DETAILED DESCRIPTION

[0055] The present disclosure may be understood by reference to the following detailed description, taken in conjunction with the drawings as described below. It is noted that, for purposes of illustrative clarity, certain elements in various drawings may not be drawn to scale.

Description of Alloy Compositions

[0056] Embodiments described herein may provide Ni-Mo-P-B, Ni-Mo-Nb-P-B, or Ni-Mo- Nb-Mn-P-B alloys. The alloys are capable of forming bulk glassy rods with diameters of 1 mm or greater. In the current disclosure, it has been discovered that the addition of Mo substituting Ni and optionally the addition of Nb substituting Mo in the disclosed ranges promote bulk-glass formation in Ni-P-B alloys. In particular, the Nb containing Ni-Mo-Nb-P-B alloys have better glass forming ability than the Ni-Mo-P-B alloys. The relative B and P contents affect the glass forming ability (GFA), as does the total metalloid content in relation to the total metal content. Furthermore, the addition of Mn substituting Mo further promotes bulk-glass formation in Ni-Mo-Nb-P-B alloys. The Mn containing Ni-Mo-Nb-Mn-P-B alloys have better glass forming ability than the Ni-Mo-Nb-P-B alloys. Additionally, glassy rods of sample metallic glasses with diameters up to 1 mm can be plastically bent.

[0057] In general, the glass-forming ability of each alloy may be assessed by determining the maximum or "critical" rod diameter in which the amorphous phase can be formed when processed by the method described herein, which is, water quenching the molten alloy in quartz capillaries. Since quartz is known to retard heat transfer, the quartz thickness is a critical parameter associated with the glass-forming ability of the sample alloys. Therefore, to quantify the glass-forming ability of each of the sample alloys, the critical rod diameter, d _c , is reported in conjunction with the associated quartz thickness, t _w , of the capillary used to process the alloy.

Ni-Mo-P-B and Ni-Mo-Nb-P-B Alloys and Metallic Glasses

[0058] Quartz capillaries with wall thicknesses that were about 10% of the tube inner diameter were used for processing the sample Ni-Mo-Nb-P-B alloys. Table 1 shows sample Ni-Mo-P-B and Ni-Mo-Nb-P-B metallic glasses that satisfy the disclosed metallic glass composition formula, Eq. (1 ), along with the associated glass forming ability and

corresponding tube wall thickness. Table 1 : Sample metallic glasses Ni-Mo-P-B and Ni-Mo-Nb-P-B compositions and the associated glass forming ability of the corresponding glass forming alloys

9 Ni ₇₂ . ₃ Mo ₆ Nb ₂ P ₁₆ . ₅ B ₃ .2 2.0 0.2

10 Ni72.3M05Nb3Pi6.5B32 2.1 0.21

11 Ni72.3MO4.5Nb3.5Pi6.5B32 2.2 0.22

12 Ni72.3M04Nb4Pi6.5B32 2.9 0.29

13 Ni72.3MO3.5Nb4.5Pi6.5B32 2.4 0.24

14 Ni72.3M03Nb5Pi6.5B32 2.3 0.23

15 Ni72.3M02Nb6Pi6.5B32 1 .6 0.16

16 Ni72.3M04Nb4Pi8.2B1.5 1 .8 0.18

17 Ni ₇₂ . ₃ M0 ₄ Nb ₄ P ₁₇ . ₇ B ₂ 2.0 0.2

18 Ni72.3M04Nb4P17.2B25 2.1 0.21

19 Ni72.3M04Nb4Pi6.7B3 2.1 0.21

20 Ni72.3M04Nb4Pi6.2B35 2.7 0.27

21 Ni72.3M04Nb4P15.95B3.75 1 .7 0.17

22 Ni72.3M04Nb4P15.7B4 1 .1 0.1 1

23 Ni72.3MO4Nb4P15.2B45 0.5 0.05

24 Ni73.3MO4Nb4P15.66B3.04 1 .9 0.19

25 Ni72.8MO4Nb4Pi 6.0sB3.12 3.0 0.3

26 Ni71 .8M04Nb4Pi 6.92B3.28 2.0 0.2

27 Ni71 .3M04Nb4P17.34B3.36 1 .5 0.15

28 Ni72.8MO3.5Nb4Pi 6.5B3 2 2.4 0.24

29 Ni72.8MO3.75Nb3.75Pi 6.5B3 2 2.4 0.24

30 Ni72.8M04Nb3.5Pi 6.5B3 2 2.3 0.23

31 Ni72.3M04Nb ₄ Pl 6B3.2Sio.5 1 .2 0.12

32 Ni72.3M04Nb4P15.5B3.2Si1 0.8 0.08

[0059] Substitution of Ni by Mo in Ni ₈₀ .3Pi 6. ₅ B _{3 2} in the range of 3 to 10 atomic percent was found to yield amorphous rods with diameters ranging from 0.5 mm to greater than 1 mm. Samples 1 -7 are Ni-Mo-P-B metallic glasses, in which the P and B contents are held constant while Ni is substituted by Mo, according to the formula Ni ₈₀ .3-xMOxPi 6. ₅ B _{3 2} , where x denotes the Mo content. Ni was substituted by Mo in the range from 3% to 9%. Of these samples, sample 5 reveals a peak in d _c of 1 .5 mm at 7.5% Mo. The GFA data for samples 1 -7 are also presented graphically in FIG. 1 .

[0060] FIG. 2 provides a data graph showing calorimetry scans for sample Ni-Mo-P-B metallic glasses (samples 1 -6) from Table 1 with varying Mo atomic concentration, according to the formula Ni ₈₀ .3-xMOxPi 6. ₅ B _{3 2} , where x denotes the Mo content. The arrows from left to right designate the glass-transition and liquidus temperatures, respectively. Differential scanning calorimetry reveals that increasing the Mo content raises the glass transition temperature, but does not substantially influence the liquidus temperatures. Lower liquidus temperature, as illustrated in the calorimetry scan, implies an improved potential for glass- forming ability.

[0061 ] Samples 8-15 are Ni-Mo-Nb-P-B metallic glasses, in which the Ni, P, and B contents are held constant while Mo is substituted by Nb, according to the formula N172.3M08- _x Nb _x P ₁₆ . ₅ B ₃ .2, where x denotes the Nb content. As shown, samples 8-15 have d _c ranging from 1 .3 mm to 1 .6 mm, which is larger than the d _c values of 0.1 mm to 1 .2 mm of samples 1 -7. In other words, further substitution of Mo by Nb in Ni72.3M08Pi6.5B32 in the range of 1 to 6 atomic percent was found to further improve the glass forming ability. Sample 12 has d _c of 2.9 mm such that the content of Mo and Nb are 4% for each. The GFA data for samples 8- 15 are presented graphically in FIG. 3.

[0062] The amorphous structure of a 2.9 mm diameter rod of metallic glass

Ni72.3M04Nb4Pi6.5B32 was verified by x-ray diffraction. FIG. 4 provides an X-ray diffractogram revealing no sharp peaks, which indicates absence of any crystals in the sample.

[0063] FIG. 5 provides a data graph showing calorimetry scans for sample metallic glasses Ni-Mo-Nb-P-B with varying Nb atomic concentration (samples 8-15), according to the formula Ni72.3M08-xNbxPi6.5B32, where x denotes the Nb content. The arrows from left to right designate the glass-transition and liquidus temperatures, respectively. As shown, the glass transition temperatures of the metallic glasses do not change much with varying Nb content, but the liquidus temperatures change with varying Nb content. Therefore, the differential scanning calorimetry reveals that the Nb substitution does not substantially influence the glass transition temperature, but the melting behavior is considerably influenced, as the liquidus temperatures go through a minimum at about 3-4%, which is near a Nb content of 4%. Again, lower liquidus temperature as illustrated in the calorimetry scan implies an improved potential for glass-forming ability.

[0064] Samples 12 and 16-23 are also metallic glasses Ni-Mo-Nb-P-B in which the Ni, Mo, Nb contents are held constant while P is substituted by B, according to the formula Ni72.3M04Nb4P19.7 xBx, where x denotes the B content. Out of these samples, sample 12 shows a peak in d _c of 2.9 mm at B content of 3.2%. The GFA data for samples 12 and 16- 23 are presented graphically in FIG. 6.

[0065] FIG. 7 provides a data graph showing the calorimetry scans for sample metallic glasses Ni-Mo-Nb-P-B with varying B atomic concentration according to the formula Ni72.3M04Nb4P19.7 xBx, where x denotes the B content (samples 17, 19, 20, and 22). The arrows from left to right designate the glass-transition and liquidus temperatures, respectively. As shown, the glass transition temperature of the metallic glasses is not greatly affected by varying the B content. However, the differential scanning calorimetry reveals that the liquidus temperature goes through a minimum near the B content of 3%. Again, lower liquidus temperature, as illustrated in the calorimetry scan, implies an improved potential for glass-forming ability.

[0066] Samples 12 and 24-27 are also Ni-Mo-Nb-P-B metallic glasses in which the Mo and Nb content is held constant while the total metalloid content is varied with the Ni content according to the formula Ni ₉ 2-xMo4Nb ₄ (Po.8376Bi 624)x, where x denotes the B content. Shifting the metalloid content in the alloy is shown to influence glass-forming ability. Out of these samples, sample 25 shows a peak in d _c of 3.0 mm at metalloid content of 19.2% B. This GFA data is presented graphically in FIG. 8.

[0067] Samples 28-30 are also Ni-Mo-Nb-P-B metallic glasses, in which the Ni, P and B content is held constant while Mo is substituted by Nb, according to the formula Ni72.sM07.5- _x Nb _x P _16.5 B ₃ .2, where x denotes the Nb content. This GFA data shows that substitution of Mo by Nb when the total Mo and Nb content is 7.5 instead of 8 does not offer any improvement in GFA.

[0068] Samples 30-31 are Ni-Mo-Nb-P-B-Si metallic glasses in which the Ni, Mo, Nb, and B content is held constant while P is substituted by Si, according to the formula

Ni72.3M04Nb4Pi 6.5-xB3.2Six, where x denotes the Si content. This GFA data reveals that when P is substituted by Si, d _c decreases.

[0069] The metallic glasses of Eq. (1 ) were found to exhibit a bending ductility.

Specifically, under an applied bending load, the disclosed metallic glasses of Eq. (1 ) were capable of undergoing plastic bending in the absence of fracture for diameters up to 1 mm. FIG. 9 provides an image showing a plastically bent 1 mm amorphous rod of sample metallic glass Ni72.3M05Nb3Pi 6.5B3 2. This demonstrates that the metallic glass Ni72.3M05Nb3Pi 6.5B3 2 rod of 1 mm diameter is able to undergo macroscopic plastic bending under load without fracturing catastrophically.

Ni-Mo-Nb-Mn-P-B Alloys and Metallic Glasses

[0070] When a small fraction of Mn of up to 2 atomic percent substitutes Mo in a Ni-Mo- Nb-P-B alloy, the glass forming ability of the alloy is enhanced. The critical rod diameter determined by processing in fused silica with a wall thickness of 0.5 mm is increased from about 1 mm for the Mn-free alloy to about 3 mm or more. In one embodiment, the Ni-Mo- Nb-P-B composition includes about 4 atomic percent Mo, about 4 atomic percent Nb, between 16 and 17 atomic percent P, between 3 and 3.5 atomic percent B, and the balance is Ni. An atomic percent of Mn between 0.5 and 1 .5 substitutes Mo in this Ni-Mo-Nb-P-B composition.

[0071] Sample metallic glasses (Samples 12, 33-35) showing the effect of substituting Mo by Mn. Metallic glasses having the formula N i72.3M04-xNb4MnxPi 6.5B3 2, are presented in Table 2 and FIG. 10. When the Mn atomic percent is between 0.5 and 1 .5, metallic glass rods with diameters greater than 2 mm can be formed. When the Mn atomic percent is at about 1 , 3-mm diameter metallic glass rods can be formed. Differential calorimetry scans for sample metallic glasses in which Mo is substituted by Mn are presented in FIG. 1 1 .

Table 2: Sample metallic glasses demonstrating the effect of substituting Mo by Mn on the glass forming ability of the Ni-Mo-Nb-P-B alloys

[0072] Among the prepared compositions, the alloy exhibiting the highest glass-forming ability is Sample 35 (Ni ₇₂ . ₃ M0 ₃ Nb ₄ Mn ₁ Pi ₆ . ₅ B _{3 2} ). The alloy is capable of forming metallic glass rods of up to 3 mm in diameter. An image of a 3 mm diameter metallic glass rod having the composition Ni ₇₂ . ₃ M0 ₃ Nb ₄ Mn ₁ Pi ₆ . ₅ B _{3 2} rod is shown in FIG. 12. An x-ray diffractogram taken on the cross section of a 3 mm diameter Ni ₇₂ . ₃ M0 ₃ Nb ₄ Mn ₁ Pi ₆ . ₅ B _{3 2} rod verifying its amorphous structure is shown in FIG. 13.

[0073] Various mechanical properties of the Ni ₇₂ . ₃ M0 ₃ Nb ₄ Mn ₁ Pi ₆ . ₅ B _{3 2} metallic glass were investigated. The measured mechanical properties include compressive yield strength, notch toughness, bending ductility, and hardness.

[0074] The compressive yield strength, a _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 o _y ensures that the material will be strong.

[0075] The stress intensity factor at crack initiation (i.e. the notch toughness), K _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 _q ensures that the material will be tough in the presence of defects. [0076] 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.

[0077] Hardness is a measure of the material's ability to resist plastic indentation. A high hardness will ensure that the material will be resistant to indentation and scratching.

[0078] These four properties characterize the material's mechanical performance under stress.

[0079] A plastic zone radius, r _p , defined as K _q ² /na _y 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 _p designates a low sensitivity of the material to flaws.

[0080] A list of measured properties for the sample metallic glass Ni72 _.3 Mo ₃ Nb ₄ Mn ₁ P16.5B3.2 (Sample 35) is presented in Table 3. The stress-strain diagram for sample metallic glass Ni72.3Mo3Nb ₄ Mn ₁ P ₁₆ .5B3.2 is presented in FIG. 14.

Table 3: Measured properties of metallic glass Ni72.3Mo3Nb ₄ Mn ₁ P ₁₆ .5B3.2.

[0081] The metallic glasses according to Eq. (2) demonstrate bending ductility.

Specifically, under an applied bending load, the metallic glasses are capable of undergoing plastic bending in the absence of fracture for diameters up to at least 1 mm. An optical image of a plastically bent amorphous rod at 1 -mm diameter section of example metallic glass is presented in FIG. 15. [0082] Lastly, the metallic glasses Ni-Mo Nb-Mn-P-B also exhibit a corrosion resistance. The corrosion resistance of example metallic glass Ni72. ₃ M0 ₃ Nb ₄ Mn ₁ Pi ₆ .5B32 is evaluated by immersion test in 6M HCI. A plot of the corrosion depth versus time is presented in FIG. 16. The corrosion depth at approximately 673 hours is measured to be about 4.7 micrometers. The corrosion rate is estimated to be 0.068 mm /year. The corrosion rate of all metallic glasses according to the current disclosure is expected to be under 1 mm/year.

Methods of Processing Sample Alloys

[0083] The alloys or alloy ingots can be produced by inductive melting of the elemental constituents in a quartz tube (i.e. fused silica tubes) under an inert atmosphere. The purity levels of the constituent elements were Ni 99.995%, Mo 99.95%, Nb 99.95%, Mn 99.9998%, P 99.9999%, and B 99.5%. The melting crucible may alternatively be a ceramic such as alumina or zirconia, graphite, or a water-cooled hearth made of copper or silver.

[0084] Metallic glass rods can be produced from the alloy ingots by re-melting the alloy ingots in quartz tubes in a furnace at 1 100°C or higher, e.g. between 1200 °C and 1400°C, under inert atmosphere, e.g. under high purity argon. Subsequently, the quartz tube containing the alloy melt can be rapidly quenched in a room-temperature water bath.

Alternatively, the bath could be iced water or oil. Metallic glass articles in general can be alternatively formed by injecting or pouring the molten alloy into a metal mold. The mold can be made of copper, brass, or steel, among other materials.

[0085] In preparing the metallic glass rods in the present disclosure, the wall thickness of the quartz tubes ranged from 0.06 mm to 0.5 mm. Fused silica is generally a poor thermal conductor. Slightly increasing the thickness of the tube wall slows the heat removal rate during the melt quenching process, thereby limiting the diameter of a rod that can be formed with an amorphous phase by a given composition. For example, the alloy

Ni72. ₃ M0 ₄ Nb ₄ Pi ₆ .5B32 is capable of forming amorphous 3 mm diameter rods (Sample 12 in Table 1 ) when processed by water quenching the high temperature melt in a fused silica tube having wall thickness of 0.3 mm. When processed in the same manner in a fused silica tube having wall thickness of 0.5 mm, the alloy Ni72. ₃ M0 ₄ Nb ₄ Pi ₆ .5B32 is capable of forming metallic glass rods of only 1 mm in diameter.

[0086] Optionally, prior to producing an amorphous article, the alloy ingots can be fluxed with a reducing agent. The ingots can be remelted in a quartz tube under inert atmosphere along with a reducing (fluxing) agent. Then, the alloy melt can be brought in contact with the molten reducing agent to allow the two melts to interact for about a time period of at least 1000 seconds (e.g. between 1 and 12 hours) at a temperature of about 1 100°C or higher (e.g. between 1200 °C and 1400 °C), and the alloy melt can be subsequently cooled by water quenching. Test Methodology for Differential Scanning Calorimetry

[0087] 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.

Test Methodology for Assessing Glass-Forming Ability

[0088] 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) can be formed when processed by the method described above. X-ray diffraction with Cu- σ radiation was performed to verify the amorphous structure of the alloys.

Test Methodology for Measuring Notch Toughness

[0089] The notch toughness of sample metallic glasses was performed on 2-mm diameter rods. The rods were notched using a wire saw with a root radius of between 0.10 and 0.13 μιη 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. At least three tests were performed, and the variance between tests is included in the notch toughness plots. 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)). Test Methodology for Measuring Compressive Yield Strength

[0090] Compression testing of sample metallic glasses was performed on cylindrical specimens 2 mm in diameter and 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 using the 0.2% proof stress criterion.

Test Methodology for Measuring Hardness

[0091] The Vickers hardness (HV0.5) of sample metallic glasses was measured using a Vickers microhardness tester. Nine tests were performed where micro-indentions were inserted on a flat and polished cross section of a 2 mm metallic glass rod using a load of 500 g and a duel time of 10 s. Test Methodology for Measuring Corrosion Resistance

[0092] The corrosion resistance of sample metallic glasses was evaluated by immersion tests in hydrochloric acid (HCI). A rod of metallic glass sample with initial diameter of 1 .99 mm, and a length of 22.55 mm was immersed in a bath of 6M HCI at room temperature. The density of the metallic glass rod was measured using the Archimedes method. 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.

[0093] The disclosed Ni-Mo-P-B, Ni-Mo-Nb-P-B, or Ni-Mo-Nb-Mn-P-B alloys with controlled ranges of Mo, Nb, Mn, and metalloids P and B have good glass forming ability, as they are capable of forming bulk metallic glass rods with diameters as large as 3 mm or larger. The metallic glasses formed from the alloys also demonstrate high strength, hardness, toughness, bending ductility, and corrosion resistance.

[0094] The combination of high glass-forming ability and the mechanical and corrosion performance of the bulk Ni-based metallic glasses make them candidates for various applications. For example, the disclosed alloys may be used in applications such as consumer electronics, dental and medical implants and instruments, luxury goods, and sporting goods, among many other applications.

[0095] 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.

[0096] 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.