EP3444370A1 - Copper based alloy for the production of metallic solid glasses - Google Patents

Abstract

The present invention relates to an alloy which has the following composition: €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ Cu 47at%-(x+y+z) (Ti a Zr b ) c Ni 7at%+x Sn 1at%+y Si z whereby c = 43 - 47 at%, a = 0.65-0.85, b=0.15-0.35, where a+b=1.00; x = 0-7 at%; y = 0-3 at%, z = 0-3 at%, where y+z ‰¤ 4 at%.

Description

Metallic glasses (also called amorphous metals) have very high strengths. Furthermore, they show no or only a very small change in volume during solidification, so that the possibility of shaping close to final shape without freezing shrinkage opens up.

If metallic glasses with a dimension of at least 1 mm x 1 mm x 1 mm can be produced with an alloy, these glasses are also referred to as solid metallic glasses or metallic solid glass (English: "Bulk Metallic Glasses" (" BMG ")).

Due to their advantageous properties, e.g. A high strength and the absence of a solidification shrinkage are metallic glasses, especially metallic solid glasses, very interesting construction materials, which are in principle suitable for the production of components in mass production processes such as injection molding, without further processing steps would be mandatory erformlich after molding.

To prevent crystallization of the alloy during cooling from the melt, a critical cooling rate must be exceeded. However, the larger the volume of the melt, the slower (with otherwise unchanged conditions) the melt cools down. Becomes a specific one Sample thickness exceeded, it comes to a crystallization before the alloy can solidify amorphous.

A measure of the glass-forming ability of an alloy is therefore, for example, the maximum or "critical" diameter up to which a specimen cast from the melt essentially still has an amorphous structure. This is also called critical casting thickness. The larger the diameter of the still amorphous solidifying sample body, the greater the glass forming ability of the alloy.

In addition to the excellent mechanical properties of metallic glasses, glass processing also provides unique processing options. Metallic glasses can not only be formed by melt-metallurgical processes, but can also be shaped by thermoplastic molding at comparatively low temperatures, analogous to thermoplastics or silicate glasses. For this purpose, the metallic glass is first heated above the glass transition point and then behaves like a highly viscous liquid that can be reshaped at relatively low forces. Following deformation, the material is again cooled below the glass transition temperature.

Depending on the application, a metallic glass may, at least temporarily, be exposed to an elevated temperature, which may even be above the glass formation temperature T _g . As already mentioned above, the thermoplastic molding also involves heating the metallic glass to a temperature above the gas formation temperature T _g . In these cases, it is desirable to have the greatest possible distance between the glass formation temperature T _g and the crystallization temperature T _x (ie the highest possible value for ΔT _x = T _x -T _g ). For example, the higher this ΔT _x value, the greater the "temperature window" for thermoplastic molding and the lower the risk of unwanted crystallization when the metallic glass is temporarily exposed to a temperature above T _g .

Improved melt-forming ability of an alloy upon cooling from the melt does not automatically result in improved heat resistance (ie, a higher ΔT _x value) of the metallic glass made from this alloy. These are usually independent parameters that may even behave in opposite directions. Thus, if it is intended to provide an alloy with as high a ΔT _x value as possible, care must also be taken that this does not occur at the expense of the glass-forming ability on cooling from the melt.

Many alloy systems, such as noble metal, Zr, Cu or fused alloys, which can form metallic glasses, are now known. An overview can be found eg at CH Shek et al., Materials Science and Engineering, R 44, 2004, p. 45-89 ,

The alloys most commonly used today for the production of metallic glasses are Zr-based alloys. A disadvantage of these alloys is the rather high material price for zirconium.

US 5,618,359 describes Zr and Cu based alloys for the production of metallic glasses. The alloys contain at least 4 alloying elements. One of the Cu-based alloys has the composition Cu ₄₅ Ti _33.8 Zr _11.3 Ni ₁₀ and can be cast to an amorphous specimen having a thickness of 4 mm.

WL Johnson et al., J. Appl. Phys., 78, No. 11, December 1995, pp. 6514-6519 , also describe Cu and Zr based alloys for the production of metallic glasses. For dimensions of at least 1 mm, these are called Metallic solid glasses (" Bulk Metallic Glasses ") called. The Cu and Zr alloys each contain a total of 4 alloying elements (Cu, Zr, Ti and Ni). The best compromise between good glass-forming ability during cooling from the melt and the highest possible ΔT _x value shows the alloy having the composition Cu ₄₇ Ti ₃₄ Zr ₁₁ Ni ₈ .

GR Garrett et al., Appl. Phys. Lett., 101, 241913 (2012), doi: 10.1063 / 1.4769997 , describe that the glass-forming ability of the alloy Cu ₄₇ Ti ₃₄ Zr ₁₁ Ni ₈ can be further improved by adding small amounts of Si, optionally in combination with Sn. Starting from the base alloy Cu ₄₇ Ti ₃₄ Zr ₁₁ Ni ₈ , Ti was substituted by Si and Ni by Sn, so that the compositions Cu ₄₇ Ti ₃₃ Zr ₁₁ Ni ₈ Si ₁ and Cu ₄₇ Ti ₃₃ Zr ₁₁ Ni ₆ Si ₁ Sn ₂ obtained were.

US 2006/0231169 A1 describes alloys for the production of metallic glasses, which may be Cu based, among others. The alloy produced in Example 3 has the composition Cu ₄₇ Ti ₃₃ Zr ₇ Ni ₈ Si ₁ Nb ₄ . Starting from the alloy Cu ₄₇ Ti ₃₄ Zr ₁₁ Ni ₈ , Ti was substituted by Si and Zr by Nb. The alloy prepared in Comparative Example 3 has the composition Cu ₄₇ Ti ₃₃ Zr ₁₁ Ni ₈ Si ₁ .

An object of the present invention is to provide an alloy having as high a ΔTx value as possible (ie, a wide temperature window for thermoplastic molding), but not at the expense of glass forming capability, and which is inexpensive to produce. Preferably, the improved thermal stability should not adversely affect other relevant properties such as hardness.

• c = 43 - 47 at%, a = 0.65-0.85, b=0.15-0.35, wobei a+b=1.00;
• x = 0-7 at%;
• y = 0-3 at%, z = 0-3 at%, wobei y+z ≤ 4 at%;

wobei die Legierung optional Sauerstoff in einer Konzentration von maximal 1,7 at% enthält und der Rest unvermeidliche Verunreinigungen sind.The object is achieved by an alloy which has the following composition:

Cu _{47at% - (x + y + z)} (Ti _a Zr _b ) _c Ni _{7at% + x} Sn _{1at% + y} Si _z

in which

• c = 43-47 at%, a = 0.65-0.85, b = 0.15-0.35, where a + b = 1.00;
• x = 0-7 at%;
• y = 0-3 at%, z = 0-3 at%, where y + z ≤ 4 at%;

wherein the alloy optionally contains oxygen in a concentration of at most 1.7 at.% and the remainder being unavoidable impurities.

In the context of the present invention, it has been recognized that alloys with the above-defined composition have high ΔT _x values and thus improved heat resistance with a still good glass-forming capability. The alloys according to the invention are thus very well suited eg for thermoplastic molding.

Preferably, y = 0-2 at% and z = 0-2 at%. Thus, when Si is present in the alloy, its concentration is at most 2 at% (e.g., 0.5 at% ≦ Si ≦ 2 at%), provided that the total concentration of Sn and Si is at most 4 at%.

In a preferred embodiment, x = 5-7 at% and y + z ≦ 4. Particularly preferred are x = 5-7 at%, y = 0-2 at% and z = 0 at%; or x = 5-7 at%, y = 0-2 at% and 0 <z ≦ 2 at% (more preferably 0.5 <z ≦ 2 at%).

Alternatively, it may also be preferred that x = 0 - <5 at% (more preferably x = 0-3 at%), y = 0-2 at% and z = 0 at%; or x = 0 - <5 at% (more preferably x = 0-3 at%), y = 0-2 at% and 0 <z ≦ 2 at% (more preferably 0.5 <z ≦ 2 at%), wherein in both cases it is preferred that y + z ≤ 4.

Preferably, a = 0.70-0.80 and b = 0.20-0.30. The values for a and b define the atomic ratio of Ti to Zr.

If the alloy according to the invention contains oxygen, it is present in a concentration of at most 1.7 at%, for example 0.01-1.7 at% or 0.02-1.0 at%.

The proportion of unavoidable impurities in the alloy is preferably less than 0.5 at%, more preferably less than 0.1 at%, even more preferably less than 0.05 at% or even less than 0.01 at%.

• 42-46 at% Cu;
• 28-40 at% Ti, bevorzugter 30 - 38 at% Ti, und 7-15 at% Zr, wobei Ti und Zr gemeinsam in einer Konzentration im Bereich von 43-47 at% vorliegen;
• 7-11 at% Ni (bevorzugter 7-9 at% Ni),
• 1-3 at% Sn und optional ≤ 2 at%Si (z.B. 0,5 at% ≤ Si ≤ 2 at%), wobei, sofern Si vorhanden ist, die Gesamtkonzentration von Sn + Si maximal 4 at% beträgt,

wobei die Legierung optional Sauerstoff in einer Konzentration von maximal 1,7 at% enthält und der Rest unvermeidliche Verunreinigungen sind.In an exemplary embodiment, the alloy according to the invention has the following composition:

• 42-46 at% Cu;
• 28-40 at% Ti, more preferably 30-38 at% Ti, and 7-15 at% Zr, wherein Ti and Zr are present together at a concentration in the range of 43-47at%;
• 7-11 at% Ni (more preferably 7-9 at% Ni),
• 1-3 at% Sn and optionally ≤ 2 at% Si (eg 0.5 at% ≤ Si ≤ 2 at%), where, if Si is present, the total concentration of Sn + Si is at most 4 at%,

wherein the alloy optionally contains oxygen in a concentration of at most 1.7 at.% and the remainder being unavoidable impurities.

• 36-42 at% Cu, bevorzugter 37-41 at% Cu;
• 28-40 at% Ti, bevorzugter 30 - 38 at% Ti, und 7-15 at% Zr, wobei Ti und Zr gemeinsam in einer Konzentration im Bereich von 43-47 at% vorliegen;
• 11-15 at% Ni,
• 1-3 at% Sn und optional ≤ 2 at%Si (z.B. 0,5 at% ≤ Si < 2 at%), wobei, sofern Si vorhanden ist, die Gesamtkonzentration von Sn + Si maximal 4 at% beträgt,

wobei die Legierung optional Sauerstoff in einer Konzentration von maximal 1,7 at% enthält und der Rest unvermeidliche Verunreinigungen sind.In a further exemplary embodiment, the alloy according to the invention has the following composition:

• 36-42 at% Cu, more preferably 37-41 at% Cu;
• 28-40 at% Ti, more preferably 30-38 at% Ti, and 7-15 at% Zr, wherein Ti and Zr are present together at a concentration in the range of 43-47at%;
• 11-15 at% Ni,
• 1-3 at% Sn and optionally ≤ 2 at% Si (eg 0.5 at% ≤ Si <2 at%), where, if Si is present, the total concentration of Sn + Si is at most 4 at%,

wherein the alloy optionally contains oxygen in a concentration of at most 1.7 at.% and the remainder being unavoidable impurities.

The composition of the alloy can be determined by inductively coupled plasma optical emission spectrometry (ICP-OEC).

Noch bevorzugter ist ΔT_x ≥ 64°C oder sogar ≥ 67°C, z.B. 64 ≤ ΔT_x ≤ 95°C oder 67 ≤ ΔT_x ≤ 90°C.The alloy according to the invention preferably has a crystallization temperature T _x and a glass transition temperature T _g which satisfy the following condition: $${\mathrm{.DELTA.T}}_{\mathrm{x}}={\mathrm{T}}_{\mathrm{x}}-{\mathrm{T}}_{\mathrm{G}}\ge \mathrm{55}\mathrm{°\; C}\mathrm{,}$$

More preferably, ΔT _{x is} ≥ 64 ° C or even ≥ 67 ° C, for example, 64 ≤ ΔT _x ≤ 95 ° C or 67 ≤ ΔT _x ≤ 90 ° C.

The glass transition temperature T _g and the crystallization temperature T _x are determined by DSC (Differential Scanning Calorimetry). In each case the onset temperature is used. The cooling and heating rates are 20 ° C / min. The DSC measurement is carried out under an argon atmosphere in an alumina crucible.

Preferably, the alloy is an amorphous alloy. In a preferred embodiment, the alloy of the invention has a crystallinity of less than 50%, more preferably less than 25%, or is even completely amorphous. A completely amorphous material shows no diffraction reflections in X-ray diffraction.
The crystalline fraction is determined by DSC as a ratio of maximum crystallization enthalpy (determined by crystallization of a fully amorphous reference sample) and the actual enthalpy of crystallization in the sample.

The invention further relates to a method for producing the alloy described above, wherein the alloy is obtained from a melt containing Cu, Ti, Zr, Ni, Sn and optionally Si.

The melt is preferably kept under an inert gas atmosphere (e.g., a noble gas atmosphere).

The constituents of the alloy may each be incorporated into the melt in their elemental form (e.g., elemental Cu, etc.). Alternatively, it is also possible that two or more of these metals are pre-alloyed in a starting alloy and then this starting alloy is introduced into the melt.

By cooling and solidification of the melt, the alloy is obtained as a solid or solid.

The melt can, for example, be poured into a mold or subjected to atomization. By atomization, the alloy can be obtained in the form of a powder whose particles have a substantially spherical shape. Suitable atomization methods are known to the person skilled in the art, for example gas atomization (for example using nitrogen or a noble gas such as argon or helium as atomizing gas), plasma atomization, centrifugal atomization or atomized atomization (eg a "rotating electrode" process (REP). designated method, in particular a "Plasma Rotating Electrode" process (PREP)). Another exemplary method is the EIGA method ("Electrode Induction Melting Gas Atomization"), inductive melting of the starting material and then gas atomization. The powder obtained via the atomization can then be used in an additive manufacturing process or subjected to a thermoplastic molding.

Due to the very good glass-forming ability of the alloy according to the invention, this can readily be obtained in the form of an amorphous alloy.

Furthermore, the present invention relates to a metallic solid glass containing or even consisting of the alloy described above.

The metallic solid glass preferably has a dimension of at least 1 mm × 1 mm × 1 mm.

Preferably, the metallic solid glass has a crystallinity of less than 50%, more preferably less than 25%, or is even completely amorphous.

The preparation of the metallic solid glass can be carried out by methods which are known to the person skilled in the art. For example, the alloy described above is subjected to additive manufacturing or thermoplastic molding or cast as a melt into a mold.

For the additive manufacturing method or the thermoplastic molding, for example, the alloy may be used in the form of a powder (for example, a powder obtained via atomization).

Using additive manufacturing processes, components with complex three-dimensional geometry can be produced directly. Additive manufacturing refers to a process in which a component is built up layer by layer on the basis of digital 3D design data by depositing material. Usually, a thin layer of the powder is first applied to the build platform. Over a sufficiently high energy input, for example in the form of a laser or electron beam, the powder is at least partially melted at the locations that specify the computer-generated design data. Thereafter, the building platform is lowered and there is another powder application.

The further powder layer is at least partially melted again and combines at the defined locations with the underlying layer. These steps are repeated until the component is in its final form.

The thermoplastic molding is usually carried out at a temperature which is between T _g and T _{x of} the alloy.

The invention will be explained in more detail with reference to the following examples.

Examples

Inventive alloys E1-E8 were prepared, the respective composition of which is given in Table 1 below. In the comparative examples, the production of the alloys CE1-CE5 was carried out.

The production conditions were identical in all examples, only the composition was varied.

The ΔT _x value (ie the distance between crystallization temperature T _x and glass formation temperature T _g ) and the critical casting thickness D _{c of} the alloys are given in Table 1.

As already mentioned above, the determination of the glass transition temperature T _g and the crystallization temperature T _{x was carried out} by DSC on the basis of the onset temperatures and with cooling and heating rates of 20 ° C / min.

• Es wird ein Zylinder 50mm Länge und einem bestimmten Durchmesser gegossen. Die Bestimmung von D_c erfolgt durch Trennen der Probe in etwas 10-15mm von der Angussstelle entfern (um die Wärmeeinflusszone auszuschließen) und XRD Messung an der Trennstelle über den gesamten Querschnitt.

The critical casting thickness D _c was determined as follows:

• It will cast a cylinder 50mm in length and a certain diameter. The determination of D _c is carried out by separating the sample in about 10-15mm from the Remove the gate (to exclude the heat affected zone) and XRD measurement at the point of separation over the entire cross section.

The alloys were produced in an electric arc furnace made of pure elements by melting and melting to form a compact body, which was melted again and poured into a Cu mold. Table 1: Composition of the alloys and their ΔT <sub> x </ sub> and D <c> values Cu [at%] Ti [at%] Zr [at%] Ni [at%] Sn [at%] Si [at%] ΔT _x [° C] _Dc [mm] CE1 47 34 11 8th 0 0 43 4 E1 45 34 11 8th 2 0 56 7 E2 45 35.8 9.2 8th 2 0 56 E3 45 37.5 7.5 8th 2 0 58 E4 41.5 34 11 11.5 2 0 64 6 E5 39.8 34 11 13.2 2 0 68 5 CE2 34.5 34 11 18.5 2 0 81 0.5 CE3 48.5 34 11 4.5 2 0 47 5 CE4 50.2 34 11 2.8 2 0 43 6 E6 44.0 34 11 8th 2 1 71 6 E7 43.5 34 11 8th 2 1.5 73 5 E8 38.2 34 11 13.3 2 1.5 85 4 CE5 42 34 11 8th 2 3 62 0.5

The alloy of Comparative Example CE1 has the composition Cu ₄₇ Ti ₃₄ Zr ₁₁ Ni ₈ . If a small amount of copper is substituted by Sn, there is a significant increase in the ΔT _x value and also the D _c value increases very clearly, see Example E1. Even with a change in the relative proportions of Ti and Zr, this improvement in the ΔT _x value compared to the starting alloy, see Examples E2 and E3.

An increase in the Ni concentration (see Examples E4 and E5) leads to a further improvement in the ΔT _x value and also the D _c value can be maintained at a relatively high level. Too high a nickel concentration leads to a significant decrease in the D _c value (see Comparative Example CE2), while a too low Ni concentration leads to a significant decrease in the ΔT _x value (see Comparative Examples CE3 and CE4).

As the examples E6-E8 show, the presence of Si leads to a further increase of the ΔT _x value, so that values of more than 70 ° C (E6 and E7) or even more than 80 ° C (E8) are obtained. The D _c values are still at a high enough level. Due to the very high ΔT _x values, the alloys are particularly well suited for thermoplastic molding. As Comparative Example CE5 shows, an excessively high total concentration of Sn + Si leads to a deterioration of the ΔT _x and D _c values.

As shown in the data of Table 1, with the alloys of the present invention, high ΔTx values (i.e., having a wide temperature window for thermoplastic molding) can be realized, while at the same time the critical casting thickness Dc can be maintained at a sufficiently high level.

For the alloys of Examples E1, E5 and E6, the Vickers hardness was also determined at a test force of 5 kiloponds (HV5). Table 2: Vickers hardness of the alloys HV5 Alloy example E1 600-640 Alloy example E5 590-612 Alloy example E6 610-630

The data in Table 2 show that the alloys according to the invention also show good hardness values.

Claims (10)

Alloy having the following composition: $${\mathrm{Cu}}_{\mathrm{47}\mathrm{at}\%-\left(\mathrm{x}+\mathrm{y}+\mathrm{z}\right)}{\left({\mathrm{Ti}}_{\mathrm{a}}{\mathrm{Zr}}_{\mathrm{b}}\right)}_{\mathrm{c}}{\mathrm{Ni}}_{\mathrm{7}\mathrm{at}\%+\mathrm{x}}{\mathrm{sn}}_{\mathrm{1}\mathrm{at}\%+\mathrm{y}}{\mathrm{Si}}_{\mathrm{z}}$$

in which c = 43-47 at%, a = 0.65-0.85, b = 0.15-0.35, where a + b = 1.00; x = 0-7 at%; y = 0-3 at%, z = 0-3 at%, where y + z ≤ 4 at%; wherein the alloy optionally contains oxygen in a concentration of at most 1.7 at.% and the remainder being unavoidable impurities. An alloy according to claim 1, wherein a = 0.70-0.80 and b = 0.20-0.30. An alloy according to claim 1 or 2, wherein y = 0-2 at% and z = 0-2 at%. An alloy according to any one of the preceding claims wherein x = 5-7 at%, y = 0-2 at% and z = 0 at%; or where x = 5-7 at%, y = 0-2 at% and 0 <z ≤ 2 at%. An alloy according to any one of claims 1-3, wherein x = 0 - <5 at%, y = 0-2 at% and z = 0 at%; or x = 0 - <5 at%, y = 0-2 at% and 0 <z ≤ 2 at%. A method of producing the alloy according to any one of claims 1-5, wherein the alloy is obtained from a melt containing Cu, Ti, Zr, Ni, Sn and optionally Si. The method of claim 6, wherein the melt is poured into a mold or subjected to atomization. Metallic solid glass containing the alloy according to any one of claims 1-5. A solid metal glass according to claim 8, having a dimension of at least 1mm x 1mm x 1mm. A method for producing a metallic solid glass, wherein the alloy according to any one of claims 1-5 is subjected to an additive manufacturing process or a thermoplastic molding or cast as a melt in a mold.