US20180066347A1

US20180066347A1 - Ni-free zr-based bmgs for black hue control

Info

Publication number: US20180066347A1
Application number: US15/415,417
Authority: US
Inventors: Yoshihiko Yokoyama; Theodore A. Waniuk; Naoto Matsuyuki
Original assignee: Apple Inc
Current assignee: Apple Inc
Priority date: 2016-09-07
Filing date: 2017-01-25
Publication date: 2018-03-08

Abstract

The disclosure provides nickel free Zr—Cu—Al metallic glass-forming alloys and metallic glasses comprising at least of Pt, Pd, and Co where the atomic fraction of Zr ranges from 50 to 70, the atomic fraction of Cu ranges from 15 to 45, the atomic fraction of Al ranges from 5 to 15, and the combined atomic fraction of Pt, Pd, and Co ranges from 1 to 10.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This patent application claims the benefit of U.S. Patent Application No. 62/384,473, entitled “NI-FREE ZR-BASED BMGS FOR BLACK HUE CONTROL,” filed on Sep. 7, 2016 under 35 U.S.C. §119(e), which is incorporated herein by reference in its entirety.

FIELD

The described embodiments relate generally to Ni-free Zirconium based metallic glass. More particularly, the present embodiments relate to eutectic and hypoeutectic Zr—Cu—Al alloys and metallic glasses including Pt, Pd, and/or Co having good glass-forming ability and high resistivity against structural relaxation embrittlement (high thermal stability). These alloys, therefore, can make black coloring by annealing in air (oxidization) while maintaining mechanical properties.

BACKGROUND

Metallic glasses are metallic alloys that do not have a crystalline structure. Instead, like glass, their structure is amorphous. Metallic glasses have a number of beneficial material properties that make them viable for use in a number of engineering applications. Some of the properties of metallic glasses include high strength, elasticity, corrosion resistance and processability from the molten state.

SUMMARY

The disclosure provides hypoeutectic Ni-Free Zr—Cu—Al—(Pd, Pt) bulk metallic glasses (BMGs). The performance of these alloys is better than other published Zr-Based BMGs from the standpoint of biocompatibility, glass-forming ability, resistance to embrittlement due to both structural relaxation and oxygen absorption, and oxide layer formation.
The disclosure provides nickel-free Zirconium (Zr) metallic glass-forming alloys and metallic glasses comprising Zr—Cu—Al with at least of one of Pd, Pt, and Co, where the atomic percent of Zr is at least 50, the atomic percent of Cu ranges from 15 to 45, the atomic percent of Al ranges from 5 to 15, and the combined atomic percent of Pd, Pt, and Co range from 1 to 15.
In another embodiment, the disclosure is directed to an alloy capable of forming a metallic glass having a composition represented by the following formula (subscripts denote atomic percentages):
Zr(_100-a-b-c)Cu_aAl_bX_c

- Where X is at least one of Pd, Pt, Co, where:
- a ranges from 15 to 45;
- b ranges from 5 to 15;
- c ranges from 1 to 10; and
- wherein the Zr atomic fraction ranges from 50 to 70.

In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 50 to 65.
In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 57 to 65.
In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 50 to 55.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 15 to 40.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 18 to 40.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 18 to 30.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 33 to 40.
In another embodiment of the metallic glass-forming alloy or metallic glass, b ranges from 9 to 11.
In another embodiment of the metallic glass-forming alloy or metallic glass b, is 10.
In another embodiment of the metallic glass-forming alloy or metallic glass, c ranges from 1 to 8.
In another embodiment of the metallic glass-forming alloy or metallic glass, c ranges from 2 to 7.
In another embodiment of the metallic glass-forming alloy or metallic glass, the ratio of Zr/Cu is 1 to 2.
In another embodiment of the metallic glass-forming alloy or metallic glass, the ratio of Zr/Cu is 1.1 to 1.6.
In another embodiment, the thermal stability of the supercooled liquid is at least 70 K.
In another embodiment, the thermal stability of the supercooled liquid is at least 80 K.
In another embodiment, the thermal stability of the supercooled liquid is at least 85 K.
In another embodiment, the thermal stability of the supercooled liquid is at least 90 K.
In another embodiment, metallic glass-forming alloy or metallic glass has a hardness of at least 400 HV.
In another embodiment, the disclosure is directed to an alloy capable of forming a metallic glass having a composition represented by the following formula (subscripts denote atomic percentages):
Zr_(100-a-b-c)Cu_aAl_bPt_c

- where:
- a ranges from 18 to 38;
- b ranges from 9 to 11;
- c ranges from 2 to 7; and
- wherein the Zr atomic fraction ranges from 50 to 70.

In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 57 to 65.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 18 to 31.
In another embodiment of the metallic glass-forming alloy or metallic glass, b is 10.
In another embodiment of the metallic glass-forming alloy or metallic glass, the thermal stability of the supercooled liquid ΔTx is at least 30° C.
In another embodiment, the metallic glass-forming alloy or metallic glass has a hardness of at least 450 HV.
In another embodiment, the metallic glass-forming alloy or metallic glass has a hardness of at least 485 HV.
In another embodiment, the disclosure is directed to an alloy capable of forming a metallic glass having a composition represented by the following formula (subscripts denote atomic percentages):
Zr(_100-a-b-c)Cu_aAl_bPd_c

- where:
- a ranges from 18 to 35;
- b ranges from 9 to 11;
- c ranges from 0.5 to 7; and
- wherein the Zr atomic fraction ranges from 50 to 70.

In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 53 to 55.
In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 57 to 65.
In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 59 to 60.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 33 to 35.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 18 to 28.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 18 to 22.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 23 to 28.
In another embodiment of the metallic glass-forming alloy or metallic glass, b is 10.
In another embodiment of the metallic glass-forming alloy or metallic glass, c ranges from 0.5 to 7.
In another embodiment of the metallic glass-forming alloy or metallic glass, c ranges from 1 to 2.
In another embodiment of the metallic glass-forming alloy or metallic glass, c ranges from 3 to 7.
In another embodiment of the metallic glass-forming alloy or metallic glass is the thermal stability of the supercooled liquid ΔTx is at least 24° C.
In another embodiment, the metallic glass-forming alloy or metallic glass has a hardness of at least 400 HV.
In another embodiment, the metallic glass-forming alloy or metallic glass has a hardness of at least 425 HV.
In another embodiment, the metallic glass-forming alloy or metallic glass has a hardness of at least 450 HV.
In another embodiment, the disclosure is directed to an alloy capable of forming a metallic glass having a composition represented by the following formula (subscripts denote atomic percentages):
Zr(_100-a-b-c)Cu_aAl_bCo_c

- where:
- a ranges from 19.5 to 38;
- b ranges from 9 to 11;
- c ranges from 2 to 7; and
- wherein the Zr atomic fraction ranges from 50 to 70.

In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 50 to 55.
In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 57 to 65.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 19.5 to 40.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 18 to 30.
In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 33 to 40.
In another embodiment of the metallic glass-forming alloy or metallic glass, the thermal stability of the supercooled liquid ΔTx is at least 70° C.
In another embodiment, the metallic glass-forming alloy or metallic glass has a hardness of at least 400 HV.
In another embodiment, the metallic glass-forming alloy or metallic glass has a hardness of at least 425 HV.
The disclosure is also directed to a method of forming a metallic glass, or an article made of a metallic glass from the metallic glass-forming alloy, comprising: heating and melting an ingot comprising the metallic glass-forming alloy under inert atmosphere to create a molten alloy, and subsequently quenching the molten alloy fast enough to avoid crystallization of the molten alloy.
In one embodiment, prior to quenching, the molten alloy is heated to at least 100° C. above the liquidus temperature of the metallic glass-forming alloy.
In another embodiment, prior to quenching, the molten alloy is heated to at least 200° C. above the liquidus temperature of the metallic glass-forming alloy.
In yet another embodiment, prior to quenching, the molten alloy is heated to at least 1100° C.
In yet another embodiment, prior to quenching, the molten alloy is heated to at least 1200° C.
In yet another embodiment, the melt of the alloy is fluxed with a reducing agent prior to forming a metallic glass.
In yet another embodiment, the reducing agent is boron oxide.
In yet another embodiment, the temperature of the melt prior to quenching to form a metallic glass is at least at the liquidus temperature of the alloy.
The disclosure is further directed to a metallic glass according to any of the above formulas and/or formed of any of the foregoing alloys.
The disclosure is also directed to an alloy or a metallic glass having compositions selected from a group consisting of Zr₅₇Cu₃₁Al₁₀Pt₂, Zr₅₇Cu₃₀Al₁₀Pt₃, Zr₆₀Cu₂₇Al₁₀Pt₃, Zr₆₀Cu₂₅Al₁₀Pt₅, Zr₆₀Cu₂₃Al₁₀Pt₇, Zr₆₀Cu₂₂Al₁₀Pt₃, Zr₆₀Cu₂₀Al₁₀Pt₅, Zr₆₀Cu₁₈Al₁₀Pt₇, Zr₅₃Cu₃₅Al₁₀Pd₂, Zr₅₅Cu₃₃Al₁₀Pd₂, Zr₅₅Cu_24.5Al₁₀Co₁Pd₃, Zr₆₀Cu_24.5Al₁₀Co₅Pd_0.5, Zr₆₅Cu_19.5Al₁₀Co₅Pd_0.5, Zr₅₇Cu₃₀Al₁₀Pd₃, Zr₅₉Cu₂₈Al₁₀Pd₃, Zr₆₀Cu₂₇Al₁₀Pd₃, Zr₆₀Cu₂₅Al₁₀Pd₅, Zr₆₀Cu₂₃Al₁₀Pd₇, Zr₆₅Cu₂₂Al₁₀Pd₃, Zr₆₅Cu₂₀Al₁₀Pd₅, Zr₆₅Cu₁₈Al₁₀Pd₇, Zr₅₀Cu₃₈Al₁₀Co₂, Zr₅₃Cu₃₅Al₁₀Co₂, Zr₅₅Cu₃₅Al₁₀Co₂, Zr₅₅Cu₃₃Al₁₀Co₁Pd₁, Zr₅₇Cu₃₀Al₁₀Co₃, Zr₅₇Cu₂₈Al₁₀Co₅, Zr₆₀Cu₂₇Al₁₀Co₃, Zr₆₀Cu₂₅Al₁₀Co₅, Zr₆₀Cu₂₃Al₁₀Co₅Pd_0.5, Zr₆₅Cu₂₂Al₁₀Co₃, Zr₆₅Cu₂₀Al₁₀Co₅, Zr₆₅Cu₁₈Al₁₀Co₇, and Zr₆₅Cu_19.5Al₁₀Co₅Pd_0.5.

DETAILED DESCRIPTION

The disclosure is directed to Ni-free Zr—Cu—Al based metallic glass including at least one of Pt, Pd, and Co having high resistivity against structural relaxation embrittlement and having a dark color (e.g., grey or black). The disclosure provides Zr—Cu—Al metallic glass-forming alloys and metallic glasses that have a high glass-forming ability along with a high thermal stability of the supercooled liquid against crystallization. The Zr—Cu—Al alloys further include at least one of Pt, Pd, Co, or combinations thereof.
As described herein, the term “Ni-free” refers to equal to or less than the amount of Ni in naturally occurring abundance. It will be recognized that in all alloys (including metallic glasses) described herein that the alloys can include incidental impurities equal to or less than natural abundance. In the context of this disclosure, an alloy being free of a certain element means that the concentration of that element in the alloy is consistent with the concentration of an incidental impurity. In the context of this disclosure, the concentration of a certain element in an alloy being 0 means that the concentration of that element is consistent with the concentration of an incidental impurity. The term “Ni-free” means that there is no Ni beyond the Ni-impurity that is present in raw materials. In various embodiments, the concentration of an incidental impurity is less than 2 atomic percent. In some embodiments, the concentration of an incidental impurity is less than 1 atomic percent, in other embodiments is less than 0.5 atomic percent, while in yet other embodiments is less than 0.1 atomic percent.
Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims.
A “critical cooling rate,” which is defined as the cooling rate required to avoid crystallization and form the amorphous phase of the metallic glass-forming alloy (i.e. the metallic glass), determines the critical plate thickness. The lower the critical cooling rate of a metallic glass-forming alloy, the larger its critical plate thickness. The critical cooling rate R_cin K/s and critical plate thickness t_cin mm are related via the following approximate empirical formula:
R _c=1000/t _c ² Eq. (1)
According to Eq. (1), the critical cooling rate for a metallic glass-forming alloy having a critical casting thickness of about 1 mm is about 10³K/s.
Generally, three categories are known in the art for identifying the ability of an alloy to form a metallic glass (i.e. to bypass the stable crystal phase and form an amorphous phase). Alloys having critical cooling rates in excess of 1012 K/s are typically referred to as non-glass formers, as it is physically impossible to achieve such cooling rates over a meaningful thickness. Alloys having critical cooling rates in the range of 105 to 1012 K/s are typically referred to as marginal glass formers, as they are able to form metallic glass foils or ribbons with thicknesses ranging from 1 to 100 micrometers according to EQ. (2). Metal alloys having critical cooling rates on the order of 103 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 metallic glass plates with 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 composition of the metallic glass-forming alloy. The compositional ranges for alloys that are marginal glass formers are considerably broader than those which are bulk glass formers.
Often in the art, a measure of glass-forming ability of an alloy is reported as the “critical rod diameter,” defined as the largest rod diameter in which the amorphous phase can be formed when processed by a method of water quenching a quartz tube having 0.5 mm thick walls containing a molten alloy.
In the present disclosure, the thermal stability of the supercooled liquid ΔTx is defined as the difference between the crystallization temperature Tx and the glass transition temperature Tg of the metallic glass, ΔTx=Tx−Tg, measured by calorimetry at a heating rate of 20 K/min.
The thermal stability of the supercooled liquid ΔTx is a property defining the ability of the metallic glass to be shaped “thermoplastically” in the supercooled liquid region, i.e. to be shaped by heating the metallic glass to a softening temperature To above the glass transition temperature Tg, applying a deformational force to shape the metallic glass over a time to that is shorter than the time it takes for the softened metallic glass to crystallize at To, and cooling the metallic glass to a temperature below Tg. The higher the thermal stability of the supercooled liquid ΔTx, the longer the available time to shape, which would allow application of the deformational force for longer periods and thus enable larger shaping strains. Also, the higher the thermal stability of the supercooled liquid ΔTx, the higher the softening temperature To to which the metallic glass can be heated, which would result in lower viscosities and thus allow larger shaping strains.
In addition to exhibiting large thermal stability of the supercooled liquid ΔTx, the metallic glass should be capable of being formed in bulk (i.e. millimeter-thick) dimensions in order to enable “thermoplastic” shaping of bulk 3-dimensional articles. That is, metallic glasses having both a high glass-forming ability as well as a large ΔTx would be suitable for “thermoplastic” shaping of bulk articles. Discovering compositional regions where the metallic glass demonstrates a high glass-forming ability is unpredictable. Discovering compositional regions where the metallic glass demonstrates a large ΔTx is equally unpredictable. Discovering compositional regions where the metallic glass demonstrates both a high glass-forming ability and a large ΔTx is even more unpredictable than both cases above, because metallic glasses that demonstrate a high glass-forming ability do not necessarily demonstrate a large ΔTx, and vice versa.
In this disclosure, compositional regions in the Ni-free Zr—Cu—Al alloy systems including at least of one of Pd, Pt, and Co are disclosed where the metallic glass-forming alloys demonstrate resistance against structural relaxation embrittlement, bulk glass-forming ability, biocompatibility, and a dark color (due to oxide layer formation).
While the role of the minor alloying element Ni in Zr-based metallic glass-forming alloy systems is glass-forming ability improvement, the glass-forming ability can be improved by protection from oxidation/oxygen absorption, even in the molten state under vacuum. Ni assists in stabilizing spontaneous formation of a surface oxide layer, thereby protecting the alloy. In addition, when trying to minimize structural relaxation embrittlement, protection of the alloy bulk from oxidation/oxygen absorption is important to maintain sufficient alloy performance.
However, a Ni-free Zr metallic glass-forming alloy or metallic glass composition is desirable for biocompatibility. Therefore, alternatives to Ni in Zr-based metallic glass-forming alloy or metallic glass composition is of interest. In the disclosure, embodiments of the metallic glass-forming alloy or metallic glass composition include Pd, Pt, Co, or combinations thereof as alternatives to Ni. The addition of the minor elements of Pd, Pt, and/or Co can increase corrosion resistance as well as retaining good glass-forming ability. The minor elements of Pd, Pt, and/or Co can also help to stabilize oxide layer formation. Additionally, the oxidation layer can affect the color/hue and/or wear resistances of the metallic glass-forming alloy or metallic glasses. A normal oxidized color surface of metallic glasses is not black. For example, Zr-based bulk metallic glasses (BMGs), such as LM105 provided by Liquid Metal, are in blue color after oxidization. However, by controlling the atomic concentration of Pd, Pt, and/or Co, the formation of an oxide layer can be controlled, thereby the color/hue and/or wear resistance can be controlled.
Also, embrittlement of Zr-based metallic glass-forming alloys and metallic glasses is caused by both oxygen/hydrogen absorption and structural relaxation (through annealing/aging). As discussed above, the oxygen/hydrogen absorption can be controlled using Pd, Pt, Co or combinations thereof as minor elements in the Zr-based metallic glass-forming alloys and metallic glasses. Additionally, adjusting the alloy composition to be eutectic (i.e. at least 50 atomic percent Zr) or hypoeutectic (i.e. at least 57 atomic percent Zr) can control the structural relaxation.
In some embodiments, the disclosure provides Zr—Cu—Al—X metallic glass-forming alloys and metallic glasses that are eutectic or hypoeutectic where the atomic percent of Zr is at least 50, where the atomic percent of Cu ranges from 15 to 45, where the atomic percent of Al ranges from 5 to 15, where X is at least of Pt, Pd, and Co, and where the combined atomic percent of Pd, Pt, and Co range from 1-15. In some embodiments, Cu ranges from 15 to 40 in the Zr—Cu—Al—X metallic glass-forming alloy or metallic glass.
In another embodiment, the disclosure is directed to an alloy capable of forming a metallic glass having a composition represented by the following formula (subscripts denote atomic percentages):
Zr_(100-a-b-c)Cu_aAl_bX_c
Where X is at least one of Pd, Pt, Co, where:
a is up to 45;
b is up to 30;
c is up to 30; and
wherein the atomic fraction of Zr is at least 50.
In some embodiments, a is up to 30 in the Zr—Cu—Al—X metallic glass-forming alloy or metallic glass.

Description of Pt Bearing Ni-Free Zr—Cu—Al Alloys and Metallic Glass Compositions

In some embodiments, the disclosure is directed to nickel free Zr—Cu—Al metallic glass-forming alloys and metallic glasses that also bear Pt. The disclosure is directed to metallic glass-forming alloys and metallic glasses having a composition represented by the following formula (subscripts denote atomic percentages):
Zr_(100-a-b-c)Cu_aAl_bPt_c
where:
a ranges from 18 to 38;
b ranges from 8 to 12;
c ranges from 2 to 7; and
wherein the Zr atomic fraction ranges from 50 to 70.
In some embodiments, the critical rod diameter of the alloy is at least 1 mm. In another embodiment of the metallic glass-forming alloy or metallic glass, the alloy or metallic glass is hypoeutectic and the atomic percent of Zr ranges from 57 to 65, a ranges from 18-31, b is 10 and c ranges from 2-7. In some embodiments, the metallic glass-forming alloy or metallic glass has the thermal stability of the supercooled liquid ΔTx that is at least 30° C.
In some embodiments, the metallic glass-forming alloy or metallic glass has a hardness of at least 450 HV. In another embodiment, the metallic glass-forming alloy or metallic glass has a hardness of at least 485 HV.
Specific embodiments of metallic glass-forming alloys or metallic glasses formed of Zr—Cu—Al comprising Pt with compositions according to the formula Zr_(100-a-b-c)Cu_aAl_bPt_care presented in Table 1. In these alloys, the atomic percent of Zr varies from 57 to 60, the atomic percent of Cu varies from 18 to 31, and the atomic percent of Pt varies from 2 to 7. Thermal and mechanical properties for the specific embodiments are summarized in Table 1.

TABLE 1

Sample metallic glasses demonstrating the effect of increasing Pt
atomic concentration by substitution of Cu according to the formula
Zr_{(100 −a-b-c)}Cu_a-Al_bPt_c

Example	Composition	T_g(° C.)	ΔT_x(° C.)	HV

1	Zr₅₇Cu₃₁Al₁₀Pt₂
2	Zr₅₇Cu₃₀Al₁₀Pt₃	417	74	496 ± 9
3	Zr₆₀Cu₂₇Al₁₀Pt₃	403	60	483 ± 8
4	Zr₆₀Cu₂₅Al₁₀Pt₅	419	49	475 ± 7
5	Zr₆₀Cu₂₃Al₁₀Pt₇	425	54	512 ± 22
6	Zr₆₀Cu₂₂Al₁₀Pt₃	393	33	461 ± 10
7	Zr₆₀Cu₂₀Al₁₀Pt₅	399	34	490 ± 11
8	Zr₆₀Cu₁₈Al₁₀Pt₇	418	31	499 ± 6

Description of Pd Bearing Ni-Free Zr—Cu—Al Alloys and Metallic Glass Compositions

In some embodiments, the disclosure is directed to nickel-free Zr—Cu—Al metallic glass-forming alloys and metallic glasses that also bear Pd. The disclosure is directed to metallic glass-forming alloys and metallic glasses having a composition represented by the following formula (subscripts denote atomic percentages):
Zr_(100-a-b-c)Cu_aAl_bPd_c
where:
a ranges from 18 to 38;
b ranges from 8 to 12;
c ranges from 2 to 7; and
wherein the Zr atomic fraction ranges from 50 to 70.
In some embodiments, the critical rod diameter of the alloy is at least 1 mm. In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 53 to 55. In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 57 to 65. In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 59 to 60.
In some embodiments of the metallic glass-forming alloy or metallic glass, a ranges from 33 to 35. In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 18 to 28. In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 18 to 22. In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 23 to 28.
In some embodiments of the metallic glass-forming alloy or metallic glass, c ranges from 0.5 to 7. In another embodiment of the metallic glass-forming alloy or metallic glass, c ranges from 1 to 2. In another embodiment of the metallic glass-forming alloy or metallic glass, c ranges from 3 to 7.
In some embodiments, the metallic glass-forming alloy or metallic glass has a thermal stability of the supercooled liquid ΔTx that is at least 24° C. In some embodiments, the metallic glass-forming alloy or metallic glass has a hardness of at least 400 HV. While, in other embodiments, the metallic glass-forming alloy or metallic glass has a hardness of at least 425 HV, while in yet other embodiments, the metallic glass-forming alloy or metallic glass has a hardness of at least 450HV.
Specific embodiments of metallic glass-forming alloys or metallic glasses formed of Zr—Cu—Al comprising Pd with compositions according to the formula Zr_(100-a-b-c)Cu_aAl_bPd_care presented in Table 2. In these alloys, the atomic percent of Zr varies from 53 to 65, the atomic percent of Cu varies from 18 to 35, and the atomic percent of Pd varies from 0.5 to 7. Thermal and mechanical properties for the specific embodiments are summarized in Table 2.

TABLE 2

Sample metallic glasses demonstrating the effect of increasing Pd
atomic concentration by substitution of Cu according to the formula
Zr_{(100 −a-b-c)}Cu_a-Al_bPd_c

Example	Composition	T_g(° C.)	ΔT_x(° C.)	HV

9	Zr₅₃Cu₃₅Al₁₀Pd₂	414	74	497
10	Zr₅₅Cu₃₃Al₁₀Pd₂	410	70	493
11	Zr₅₅Cu_24.5Al₁₀Co₁Pd₃	396	88	493
12	Zr₆₀Cu_24.5Al₁₀Co₅Pd_0.5	391	92	460
13	Zr₆₅Cu_19.5Al₁₀Co₅Pd_0.5	372	89	424
14	Zr₅₇Cu₃₀Al₁₀Pd₃	395	78	480 ± 7
15	Zr₅₉Cu₂₈Al₁₀Pd₃	400	66	499 ± 7
16	Zr₆₀Cu₂₇Al₁₀Pd₃	392	73	473 ± 7
17	Zr₆₀Cu₂₅Al₁₀Pd₅	397	56	494 ± 8
18	Zr₆₀Cu₂₃Al₁₀Pd₇	396	55	497 ± 4
19	Zr₆₅Cu₂₂Al₁₀Pd₃	374	48	450 ± 12
20	Zr₆₅Cu₂₀Al₁₀Pd₅	378	39	443 ± 2
21	Zr₆₅Cu₁₈Al₁₀Pd₇	397	24	467 ± 9

Description of Co Bearing Ni-Free Zr—Cu—Al Alloys and Metallic Glass Compositions

In some embodiments, the disclosure is directed to nickel free Zr—Cu—Al metallic glass-forming alloys and metallic glasses that also bear Co. The disclosure is directed to metallic glass-forming alloys and metallic glasses having a composition represented by the following formula (subscripts denote atomic percentages):
Zr_(100-a-b-c)Cu_aAl_bCo_c
where:
a ranges from 18 to 38;
b ranges from 8 to 12;
c ranges from 2 to 7; and
wherein the Zr atomic fraction ranges from 50 to 70.
In some embodiments, the critical rod diameter of the alloy is at least 1 mm. In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 50 to 55. In another embodiment of the metallic glass-forming alloy or metallic glass, the atomic percent of Zr ranges from 57 to 65.
In some embodiments of the metallic glass-forming alloy or metallic glass, a ranges from 19.5 to 40. In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 18 to 30. In another embodiment of the metallic glass-forming alloy or metallic glass, a ranges from 33 to 40.
In some embodiments of the metallic glass-forming alloy or metallic glass, c ranges from 0.5 to 7. In another embodiment of the metallic glass-forming alloy or metallic glass, c ranges from 1 to 2. In another embodiment of the metallic glass-forming alloy or metallic glass, c ranges from 3 to 7.
In some embodiments, the metallic glass-forming alloy or metallic glass has a thermal stability of the supercooled liquid ΔTx that is at least 77° C.
In some embodiments, the metallic glass-forming alloy or metallic glass has a hardness of at least 400 HV. While, in other embodiments, the metallic glass-forming alloy or metallic glass has a hardness of at least 425 HV, while in yet other embodiments the metallic glass-forming alloy or metallic glass has a hardness of at least 475HV.
Specific embodiments of metallic glass-forming alloys or metallic glasses formed of Zr—Cu—Al comprising Cu with compositions according to the formula Zr_(100-a-b-c)Cu_aAl_bPd_care presented in Table 3. In these alloys, the atomic percent of Zr varies from 50 to 65, the atomic percent of Cu varies from 18 to 38, and the atomic percent of Co varies from 1 to 7. Thermal and mechanical properties for the specific embodiments are summarized in Table 3.

TABLE 3

Sample metallic glasses demonstrating the effect of increasing Co
atomic concentration by substitution of Cu according to the formula
Zr_{(100 −a-b-c)}Cu_a-Al_bPd_c

Example	Composition	T_g(° C.)	ΔT_x(° C.)	HV

22	Zr₅₀Cu₃₈Al₁₀Co₂	418	90	513
23	Zr₅₃Cu₃₅Al₁₀Co₂	418	77	494
24	Zr₅₅Cu₃₅Al₁₀Co₂	401	81	486
25	Zr₅₅Cu₃₃Al₁₀Co₁Pd₁	396	88	493
26	Zr₅₇Cu₃₀Al₁₀Co3	397	80	477
27	Zr₅₇Cu₂₈Al₁₀Co₅	394	86	472
28	Zr₆₀Cu₂₇Al₁₀Co₃	383	90	459
29	Zr₆₀Cu₂₅Al₁₀Co₅	383	96	456
30	Zr₆₀Cu₂₃Al₁₀Co₅Pd_0.5	391	92	460
31	Zr₆₅Cu₂₂Al₁₀Co₃	371	94	435
32	Zr₆₅Cu₂₀Al₁₀Co₅	372	85	433
33	Zr₆₅Cu₁₈Al₁₀Co₇	370	77	434
34	Zr₆₅Cu_19.5Al₁₀Co₅Pd_0.5	372	89	424

From a cosmetic viewpoint of colored oxide layer formation on Ni-free Zr-based metallic glass-forming alloys or metallic glasses, tough and uniform oxide layer formation helps to control color. The color of the oxide surface of the metallic glass surface can be affected by alloy composition. The texture of the metallic glass surface can also be affected by alloy composition. For example, small additives of Pt, Pd, and/or Co can support to stabilize the oxide layer forming and can provide protection of ion release under corrosion environment
Furthermore, the metallic glass-forming alloys and metallic glasses in accordance with embodiments described above characterized by the molar ratio of Zr/Cu from 1.1 to 1.6 tends to show the black color surface by oxidization annealing at Tg-15 in air-atmosphere.
The metallic glass-forming alloys and metallic glasses in accordance with embodiments can be used for black coloring by simple blasting and oxidizing in Air at Tg-15K. The blasting and oxidizing method can control the color and texture of the oxidized metallic glass surface. Uniform surfaces (i.e., without surface features) and dark (e.g., black) colored surfaces can be achieved by the combination of blasting and oxidization steps. Tables 4-6 summarize the parameters of L*a*b* space color after black coloring of embodiments of Ni-free Zr based metallic glass-forming alloys and metallic glasses described above, by changing of black coloring condition. Standard methods can be used to evaluate cosmetic appeal, including color, gloss, and haze. The color of objects may be determined by the wavelength of light that is reflected or transmitted without being absorbed, assuming incident light is white light. The visual appearance of objects may vary with light reflection or transmission. Additional appearance attributes may be based on the directional brightness distribution of reflected light or transmitted light, commonly referred to glossy, shiny, dull, clear, and haze, among others. The quantitative evaluation may be performed based on ASTM Standards on Color & Appearance Measurement, ASTM E-430 Standard Test Methods for Measurement of Gloss of High-Gloss Surfaces, including ASTM D523 (Gloss), ASTM D2457 (Gloss on plastics), ASTM E430 (Gloss on high-gloss surfaces, haze), and ASTM D5767 (DOI), among others. The measurements of gloss, haze, and DOI may be performed by testing equipment, such as Rhopoint IQ.
The metallic glasses can be treated by blasting-oxidizing (BO), and blasting-oxidizing-blasting (BOB) to control the L*, a*, and b* values. In particular, the BO and BOB control the black color. The BOB controls the blueish black color (i.e. b*<0) to be real black (i.e. B* is approximately zero). The initial blast can use zirconia fine media (diameter less than about 100 μm) with high blasting pressure and the final blast can be gentle with same media.
In various embodiments, the L*, a*, and/or b* color values can be controlled in accordance with the embodiments of the disclosure. For instance, the a* values can be less than or equal to 1, alternatively less than or equal to 0.75, alternatively less than or equal to 0.5, or alternatively less than or equal to 0.3. In other embodiments, the a* values can be greater than or equal to −1, alternatively be less than or equal to −0.75, alternatively greater than or equal to −0.5, or alternatively greater than or equal to −0.3.
Further, the b* values can be less than or equal to 5, less than or equal to 4, less than or equal to 3, less than or equal to 1, less than or equal to 0.50. Further, the b* values can be greater than or equal to −5, greater than or equal to −4, greater than or equal −3, greater than or equal to + or −1, greater than or equal to + or −0.50.
In various aspects, the L* value can be less than or equal to 50. Alternatively, the L* value can be less than or equal to 45. Alternatively, the L* value can be less than or equal to 40. Alternatively, the L* value can be less than or equal to 35. Alternatively, the L* value can be greater than or equal to 30. Alternatively, the L* value can be greater than or equal to 35. Alternatively, the L* value can be greater than or equal to 40. Alternatively, the L* value can be greater than or equal to 45.
As mentioned above, the addition of the minor elements of Pd, Pt, and/or Co can also increase corrosion resistance. The corrosion resistance of example alloy compositions in accordance with embodiments as described were evaluated by a salt-mist spray corrosion test (ASTM B117) for 24 hours. ATSM B117 is a standardized test for checking corrosion resistance of materials and surface coatings. Results of the corrosion testing are reported as a rating letter for a period of time (e.g., 24 hours). Tables 7 and 8 show the corrosion ratings for sample alloy compositions in accordance with embodiments of the disclosure. As shown in the tables, some of samples alloy compositions containing Pt have improved corrosion resistance. Also, samples of alloy compositions containing Co and Pd show enhanced corrosion resistance in comparison to the ternary Zr—Cu—Al BMGs systems.
In order to realize the mechanism of corrosion resistance, the micro-structure of the black-colored (oxidized) Ni-free Zr-based BMGs was observed. The surface region of the black colored Zr₅₇Cu₃₁Al₁₀Pt₂alloys was mapped using EDX. The noteworthy point, the distribution of Pt element is quite uniform even in the oxide layer. In contrast, Cu and Al are segregated at the interfaces in oxide layer, even though the distribution of Cu and Al is homogeneous in BMG matrix. As concluded, the quite uniform distribution of 4^thelement of Pt even in oxide layer is one of reason to increase the corrosion resistance.

TABLE 7

Sample metallic glasses demonstrating the corrosion resistance effect of
increasing Pt and Pd atomic concentration by substitution of Cu according
to the formula Zr_{(100 −a-b-c)}Cu_a-Al_bPd_con the Lab* space color

		Corrosion Rating for
Example	Composition	ASTM B117	Oxidation Method

	Zr₅₇Cu₃₀Al₁₀Pd₃	d
	Zr₅₇Cu₃₀Al₁₀Pt₃	b	BO
	Zr₅₉Cu₂₈Al₁₀Pd₃	d
	Zr₆₀Cu₂₇Al₁₀Pd₃	d
	Zr₆₀Cu₂₅Al₁₀Pd₅	d
	Zr₆₀Cu₂₃Al₁₀Pd₇	d	BOB
	Zr₆₀Cu₂₇Al₁₀Pt₃	b

TABLE 8

Sample metallic glasses demonstrating the corrosion resistance effect of
increasing Pt and Pd atomic concentration by substitution of Cu according
to the formula Zr_{(100 −a-b-c)}Cu_a-Al_bPd_con the Lab* space color

		Corrosion Rating for
Example	Composition	ASTM B117	Oxidation Method

	Zr₆₀Cu₂₅Al₁₀Pt₅	c	BO
	Zr₆₀Cu₂₃Al₁₀Pt₇	b	BO
	Zr₆₅Cu₂₂Al₁₀Pd₃	c	BOB
	Zr₆₅Cu₂₀Al₁₀Pd₅	d	BOB
	Zr₆₅Cu₁₃Al₁₀Pd₇	d
	Zr₆₅Cu₂₂Al₁₀Pt₃	b	BO
	Zr₆₅Cu₂₀Al₁₀Pt₅	b
	Zr₅₀Cu₁₈Al₁₀Pt₇	b

In order to understand the mechanism contributing to the enhancement of corrosion resistance, the micro-structure of the black-colored (oxidized) Ni-free Zr-based samples of the alloy composition Zr₅₇Cu₃₁Al₁₀Pt₂was examined using EDX mapping of surface region. From the EDX mapping it was observed that the distribution of the Pt minor element was substantially uniformly distributed in the oxide layer. In contrast, it was observed that the Cu and Al elements were segregated at the interfaces in oxide layer, even though the distribution of Cu and Al is homogeneous in BMG matrix. Thus, without wishing to be held to a specific mechanism or mode of action, it appears that the uniform distribution of the minor element (Pt, Pd, and/or Co) in the oxide layer contributes to the enhanced corrosion resistance.
The alloys described herein can be valuable in the fabrication of electronic devices using a metallic glass-containing part. An electronic device herein can refer to any electronic device known in the art. For example, it can be a telephone, such as a mobile phone, and a land-line phone, or any communication device, such as a smart phone, including, for example an iPhone®, and an electronic email sending/receiving device. It can be a part of a display, such as a digital display, a TV monitor, an electronic-book reader, a portable web-browser (e.g., iPad®), and a computer monitor. It can also be an entertainment device, including a portable DVD player, conventional DVD player, Blue-Ray disk player, video game console, music player, such as a portable music player (e.g., iPod®), etc. It can also be a part of a device that provides control, such as controlling the streaming of images, videos, sounds (e.g., Apple TV®), or it can be a remote control for an electronic device. It can be a part of a computer or its accessories, such as the hard drive tower housing or casing, laptop housing, laptop keyboard, laptop track pad, desktop keyboard, mouse, and speaker. The article can also be applied to a device such as a watch or a clock.
The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not target to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Claims

What is claimed is:

1. A metallic glass-forming alloy having a composition represented by the following formula (subscripts denote atomic percentages):

Zr_(100-a-b-c)Cu_aAl_bX_c

where:

X is at least one of Pt, Pd, and Co

a ranges from 15 to 45 at %;

b ranges from 5 to 15 at %;

c ranges from 1 to 10 at %;

wherein the critical rod diameter of the metallic glass-forming alloy is at least 1 mm, and

wherein a thermal stability of the supercooled liquid of the composition is at least 70 K.

2. The metallic glass-forming alloy of claim 1 wherein the atomic fraction of Zr ranges from 55 to 65 at %.

3. The metallic glass-forming alloy of claim 1 wherein the atomic fraction of Cu ranges from 15 to 40 at %.

4. The metallic glass-forming alloy of claim 1 wherein b is 8 to 12 at %.

5. The metallic glass-forming alloy of claim 1 wherein a is from 18 to 38, b is from 8 to 12, and c is from 2 to 7.

6. The metallic glass-forming alloy of claim 1 wherein X is Pt.

7. The metallic glass-forming alloy of claim 6 wherein a is from 18 to 31, b is from 8 to 12, and c is from 2 to 7.

8. The metallic glass-forming alloy of claim 7 wherein the alloy has a brightness L*from 35 to 50, an a* value from −0.1 to 1, and a b* value from −0.25 to +5.

9. The metallic glass-forming alloy of claim 1 wherein X is Pd or Pt.

10. The metallic glass-forming alloy of claim 9 wherein a ranges from 18 to 35, b is from 8 to 12, and c ranges from 2 to 7.

11. The metallic glass-forming alloy of claim 10 wherein the alloy has a brightness L* from 36 to 444, an a* value from −0.5 to 0.5, and a b* value from −5.25 to 1.

12. The metallic glass-forming alloy of claim 8 wherein a is from 18 to 38, b is from 8 to 12, and c is from 2 to 7.

13. The metallic glass-forming alloy of claim 13 wherein the alloy has a brightness L* from 35 to 45, an a* value from −0.3 to 0.25, and a b* value from −4.5 to 6.

14. A metallic glass comprising an alloy where a composition of the alloy is represented by the following formula (subscripts denote atomic percentages):

Zr_(100-a-b-c)Cu_aAl_bX_c

where:

a ranges from 15 to 45;

b ranges from 5 to 15;

c ranges from 1 to 10;

where X can is selected from at least one of Pd, Pt, Co, and a combinations thereof.

15. The metallic glass of claim 14 wherein a ranges from 15 to 40.

16. The metallic glass of claim 14 wherein a ranges from 18 to 38, b is 10, and c ranges from 2 to 7.

17. A method of producing the metallic glass comprising:

melting an alloy into a molten state; where the alloy has a composition represented by the following formula (subscripts denote atomic percentages):

Zr_(100-a-b-c)Cu_aAl_bX_c

where:

a ranges from 15 to 45;

b ranges from 5 to 15;

c ranges from 1 to 10;

where X can is selected from at least one of Pd, Pt, Co, and a combinations thereof; and

quenching the melt at a cooling rate sufficiently rapid to prevent crystallization of the alloy.

18. The method of claim 17 wherein the atomic fraction of Cu ranges from 15 to 40 at %.

19. The method of claim 17, further comprising fluxing the melt with a reducing agent prior to quenching.

20. The method of claim 17 wherein the temperature of the melt prior to quenching is at least 1100° C.