EP3695920B1 - Robust ingot for the production of components made of metallic solid glasses - Google Patents

Description

The invention relates to a method for producing mechanically and thermally stable ingots (also called preforms) from alloys that can form a metallic solid glass. Furthermore, the invention relates to an ingot of a solid glass-forming alloy that is produced using the method according to the invention and the use of this ingot in a casting method.

Since their discovery around 50 years ago at the California Institute of Technology, metallic glasses have been the subject of extensive research. Over the years, it has been possible to continuously improve the processability and properties of this material class. While the first metallic glasses were still simple, binary alloys (made up of two components), the production of which required cooling rates in the range of 10 ⁶ Kelvin per second (K/s), newer, more complex alloys can be produced at significantly lower cooling rates in the range of a few K /s transition to the glass state. This has a significant impact on the process control and the components that can be produced. The cooling rate from which there is no crystallization of the melt and the melt solidifies as glass is referred to as the critical cooling rate. It is a system-specific variable that is heavily dependent on the composition of the melt and also determines the maximum component thicknesses that can be achieved. If you consider that the thermal energy stored in the melt has to be transported away quickly enough through the system, it becomes clear that systems with high critical cooling rates can only be used to produce components with a low thickness. Initially, metallic glasses were therefore mostly produced using the melt spinning process. The melt is scraped onto a rotating copper wheel and solidifies like glass in the form of thin ribbons or foils with thicknesses in the range of a few hundredths to tenths of a millimeter. Due to the development of new, complex alloys with significantly lower critical cooling rates, other manufacturing processes can increasingly be used. Today's glass-forming metallic alloys can already be converted into the glass state by pouring a melt into cooled copper moulds. The achievable component thicknesses are in the range of a few millimeters to centimeters, depending on the alloy. Such alloys are referred to as bulk metallic glasses (BMG). In the context of the present invention, a metallic solid glass is to be understood as meaning a material with a critical casting thickness of at least one millimeter.

A large number of such alloy systems are known today. They are usually classified according to their composition, with the alloying element with the highest weight percentage being referred to as the base element. The existing systems include, among other things, precious metal-based alloys such as gold, platinum and palladium-based metallic bulk glasses, early transition metal-based alloys such as titanium or zirconium-based metallic bulk glasses, late transition metal-based systems, e.g. based on Copper, nickel or iron, but also systems based on rare earth metals, e.g. neodymium or terbium.

• eine höhere spezifische Festigkeit, was zum Beispiel dünnere Wandstärken ermöglicht,
• eine höhere Härte, wodurch die Oberflächen besonders kratzfest sein können,
• eine viel höhere elastische Dehnbarkeiten und Resilienzen,
• eine thermoplastische Formbarkeit und
• eine höhere Korrosionsbeständigkeit.

Metallic solid glasses typically have at least one of the following properties compared to classic, crystalline metals:

• a higher specific strength, which, for example, allows thinner walls,
• a higher degree of hardness, which means that the surfaces can be particularly scratch-resistant,
• a much higher elastic extensibility and resilience,
• thermoplastic formability and
• higher corrosion resistance.

Components made of metallic solid glass can be produced using casting processes, since the necessary cooling rates for amorphous solidification can be achieved with these processes. In order to obtain amorphous components from a metallic bulk glass, it is usually necessary to quickly transfer the melt of a bulk glass-forming alloy into a mold. This filling of the mold with the melt preferably takes place by injection (injection molding) or sucking in (suction molding). In this way, the high cooling rates can be achieved and three-dimensional components made of metallic solid glass can be manufactured. Small manufacturing tolerances can be achieved by using casting processes such as injection molding.

Ingots of the alloy to be processed are necessary for casting processes, which serve as a supply of material to be processed and can be melted homogeneously. To do this, the ingots must have a sufficient volume so that enough material is available for the entire cast component and the additional spaces in the mold (the sprue ) can also be filled. Therefore, ingots that are as large as possible are desirable.

To produce ingots from bulk glass-forming alloys, a homogeneous bulk glass-forming alloy is first produced. To do this, the individual components are mixed together and heated above the melting point, resulting in a homogeneous alloy. The individual components can be melted, for example, in an arc or by means of inductive heating. the The homogeneous alloy is then poured into molds and cooled to form an ingot. Generally, these ingots are in the form of cylindrical rods. In order for the ingots to contain enough material to completely fill the mold for a casting process for a three-dimensional component, the ingots must be sufficiently dimensioned. Typical diameters of cylindrical ingots made of bulk glass-forming alloys are in the range of about 20 mm. The length of an ingot is preferably at least 3 cm.

Out of US5279349 methods are already known in which amorphous molded parts can be obtained by using preheated molds. In this case, the melt is pressurized as it cools. Very small, amorphous ingots can be produced with such processes, since the molded part must not exceed the critical casting thickness in any dimension. Because of their limited size, such fully amorphous ingots can only provide a very limited amount of material for a casting process. When used in casting processes, amorphous ingots also have the disadvantage that they can only be melted slowly because of their comparatively poor thermal conductivity.

Manufacturing high quality ingots from materials with a high critical casting thickness and with dimensions larger than the critical casting thickness is difficult. On the one hand, there is a considerable amount of waste during production, since known ingots often shatter during the production process. On the other hand, some of the conventionally produced ingots shatter during transport or when they are heated up during the actual production step of a three-dimensional component using the casting process. If the ingots shatter during the manufacture of a three-dimensional component, this is disadvantageous because the heat conduction is interrupted by the cracks. This increases the process time for the production of three-dimensional components. In order to avoid cracking of conventional ingots that have survived the manufacturing process undamaged, the ingot must be heated very slowly to the melting point. Typically, ingot melting takes at least 80 seconds.

task

An object of the present invention was to provide an ingot made from a solid glass-forming alloy with a high critical casting thickness, which does not shatter during the production process and can be heated up more quickly during further thermal processing, such as injection molding.

Furthermore, the object of the invention was to provide a method for producing an ingot from a solid glass-forming alloy with a high critical casting thickness that does not shatter during the production process.

Another object of the invention was to provide ingots made of bulk glass-forming alloys that can be heated faster than conventional ingots.

A contribution to solving at least one of the tasks mentioned is made by the subject matter of the independent claims.

1. a. Bereitstellen einer homogenen Schmelze (10) einer Massivglas-bildenden Legierung,
2. b. Gießen der homogenen Schmelze in eine Gussform, wobei die Gussform an der Kontaktfläche mit der Schmelze mindestens 5 Sekunden nicht unter die Glasbildungstemperatur der Legierung abkühlt, und
3. c. Abkühlen der Schmelze unter die Glasübergangstemperatur der Massivglas-bildenden Legierung unter Erhalt des Ingots (20).

A first aspect of the invention relates to a method for producing an ingot (20) of a bulk glass-forming alloy, comprising the steps:

1. a. Providing a homogeneous melt (10) of a solid glass-forming alloy,
2. b. pouring the homogeneous melt into a mold, the mold not cooling below the glass formation temperature of the alloy at the contact surface with the melt for at least 5 seconds, and
3. c. cooling the melt below the glass transition temperature of the bulk glass-forming alloy to obtain the ingot (20).

According to the invention, the composition of the solid glass-forming alloy is not further restricted. A solid glass-forming alloy is preferably to be understood as meaning an alloy with a critical casting thickness of at least one millimeter. This means that such an alloy can solidify amorphously up to a thickness of one millimeter at a suitable cooling rate.

1. A. Metallen aus Gruppe IA und IIA des Periodensystems, z.B. Magnesium, Calcium,
2. B. Metallen aus Gruppe IIIA und IVA, z.B. Aluminium oder Gallium,
3. C. frühen Übergangsmetallen aus den Gruppen IVB bis VIIIB, wie z.B. Titan, Zirkon, Hafnium, Niob, Tantal, Chrom, Molybdän, Mangan,
4. D. späten Übergangsmetallen aus den Gruppen VIIIB, IB, IIB, wie z.B. Eisen, Kobalt, Nickel, Kupfer, Palladium, Platin, Gold, Silber, Zink,
5. E. Seltenerdmetallen, wie z.B. Scandium, Yttrium, Terbium, Lanthan, Cer, Neodym. Gadolinium und
6. F. Nichtmetallen, wie z.B. Bor, Kohlenstoff, Phosphor, Silizium, Germanium, Schwefel Bevorzugte Kombinationen von Elementen in metallischen Massivgläser sind ausgewählt aus:
   • späten Übergangsmetallen und Nichtmetallen, wobei das späte Übergangsmetall die Basis darstellt, beispielsweise Ni-P, Pd-Si, Au-Si-Ge, Pd-Ni-Cu-P, Fe-Cr-Mo-P-C-B,
   • frühen und späten Übergangsmetallen, wobei beide Metalle die Basis darstellen können, wie z.B. Zr-Cu, Zr-Ni, Ti-Ni, Zr-Cu-Ni- Al, Zr-Ti-Cu-Ni-Be,
   • Metalle aus Gruppe B mit Seltenerdmetallen, wobei das Metall B die Basis darstellt, wie z.B. Al-La, AI-Ce, Al-La-Ni-Co, La-(Al/Ga)-Cu-Ni, und
   • Metalle aus Gruppe A mit späten Übergangsmetallen, wobei das Metall A die Basis darstellt, wie z.B. Mg-Cu, Ca-Mg-Zn, Ca-Mg-Cu

Alloys forming solid glass are to be understood as meaning those which, under certain thermal conditions, can have a metallic bonding character in the solid state and at the same time have an amorphous, ie non-crystalline, phase. The alloy can be based on different elements. "Based" in this context means that the element named in each case represents the largest proportion in relation to the weight of the alloy. Constituents, which preferably also form the basis of the alloy, can be selected, for example, from:

1. A. Metals from groups IA and IIA of the periodic table, e.g. magnesium, calcium,
2. B. Group IIIA and IVA metals, e.g. aluminum or gallium,
3. C. early transition metals from groups IVB to VIIIB, such as titanium, zirconium, hafnium, niobium, tantalum, chromium, molybdenum, manganese,
4. D. late transition metals from groups VIIIB, IB, IIB, such as iron, cobalt, nickel, copper, palladium, platinum, gold, silver, zinc,
5. E. Rare earth metals such as scandium, yttrium, terbium, lanthanum, cerium, neodymium. gadolinium and
6. F. Non-metals such as boron, carbon, phosphorus, silicon, germanium, sulfur Preferred combinations of elements in metallic bulk glasses are selected from:
   • late transition metals and non-metals where the late transition metal is the base, for example Ni-P, Pd-Si, Au-Si-Ge, Pd-Ni-Cu-P, Fe-Cr-Mo-PCB,
   • early and late transition metals, both metals can be the basis, such as Zr-Cu, Zr-Ni, Ti-Ni, Zr-Cu-Ni-Al, Zr-Ti-Cu-Ni-Be,
   • Group B metals with rare earth metals where the metal B is the base such as Al-La, Al-Ce, Al-La-Ni-Co, La-(Al/Ga)-Cu-Ni, and
   • Group A metals with late transition metals, where the metal A is the base, such as Mg-Cu, Ca-Mg-Zn, Ca-Mg-Cu

Further, particularly preferred examples of alloys that can form metallic bulk glasses are selected from the group consisting of Ni-Nb-Sn, Co-Fe-Ta-B, Ca-Mg-Ag-Cu, C-oFe-B-Si -Nb, Fe-Ga-(Cr,Mo)(P,C,B), Ti-Ni-Cu-Sn, Fe-Co-Ln-B, Co-(Al,Ga)-(P,B,Si ), Fe-B-Si-Nb and Ni-(Nb,Ta)-Zr-Ti. In particular, the metallic bulk glass can be a Zr-Cu-Al-Nb alloy. In addition to zirconium, this Zr-Cu-Al-Nb alloy preferably also has 23.5-24.5% by weight copper, 3.5-4.0% by weight aluminum and 1.5-2.0% by weight On niobium, the proportions by weight adding up to 100% by weight. The latter alloy is commercially available under the name ^AMZ4® from Heraeus Deutschland GmbH. In a further, particularly preferred embodiment, the alloy forming solid glass can contain or consist of the elements zirconium, titanium, copper, nickel and aluminum. Particularly stable ingots can be produced from alloys of this composition that form solid glass. A particularly well suited alloy for the production of stable inogts has the composition Zr _52.5 Ti ₅ Cu _17.9 Ni _14.6 Al ₁₀ , the indices indicating mol % of the respective elements in the alloy.

Due to the intrinsic heat conduction of the material, even with the maximum achievable cooling rate, there is a maximum casting thickness, which the casting must be below in at least one dimension in order to still be able to form a homogeneous amorphous phase. The alloy that forms solid glass preferably has a critical casting thickness of at least 5 mm, in particular at least 7 mm and entirely particularly preferably of at least 10 mm. In the context of the present invention, the maximum casting thickness is a measure of how easy or difficult it is for a metallic alloy to bring it into the glass state.

In order to determine the critical cast thickness within the scope of the invention, the alloy to be measured is processed in an electric arc to form a homogeneous melt and then poured into a water-cooled copper mold (also called permanent mold). The mass of the copper mold is preferably at least a factor of 7 greater than the mass of the melt of the alloy to be determined. The temperature of the homogeneous melt before casting is preferably at least 200° C., in particular 300° C. and very particularly preferably at least 400° C. above the melting temperature. The temperature of the copper mold is 20°C. To determine the critical casting thickness, cylindrical molded parts are cast with increasing diameters at a distance of 1 mm (e.g. 2mm, 3mm, 4mm, 5mm, 6mm, etc.). The cylindrical molded parts produced are examined for their crystalline content using differential scanning calorimetry (DSC). The cylinder diameter that is one millimeter smaller than the cylinder diameter at which the formation of a crystalline phase is first measured by DSC is given as the critical casting thickness. DSC method 2) as described herein was used to determine the presence of a crystalline phase.

In step a) of the present invention, a homogeneous melt of a bulk glass-forming alloy is provided. The homogeneous melt is preferably prepared by melting the individual elements of the alloy together. The individual elements are preferably melted in an arc or by means of inductive heating. The temperature of the homogeneous melt is preferably at least 200° C., in particular at least 300° C., and very particularly preferably at least 400° C., above the melting temperature of the respective solid glass-forming alloy. In a preferred embodiment, the temperature of the melt, measured in degrees Celsius, is at least 20%, in particular at least 50%, above the melting temperature of the alloy, since particularly stable ingots can be produced as a result.

In step b), the homogeneous melt is poured into a casting mold. According to the invention, the shape of the mold is not further restricted. The mold is preferably cylindrical. The volume of the casting mold to be filled preferably has dimensions which are greater in all three spatial directions than the critical casting thickness of the alloy forming solid glass. The material of the mold can preferably be selected from steel, titanium, copper, ceramic or graphite. The mold preferably has a device with which the mold can be actively heated and/or cooled. In one embodiment of the invention, the mold can be actively heated, eg by electrical heating.

The ratio between the weight of the mold and the weight of the melt is preferably in the range of 7:1 or more, more preferably in the range of 10:1 or more. In a preferred embodiment of the invention, the casting mold can be coated in the area that comes into contact with the melt. The material of this coating of the mold is preferably selected from the group consisting of boron nitride, aluminum oxide (eg Al ₂ O ₃ ) and yttrium oxide (eg Y ₂ O ₃ ). The coating preferably has or consists of a powder. The thickness of the coating, in particular the powder coating, can be in the range of 10-50 μm in one embodiment. A layer of powder can have an advantageous effect on the mechanical properties of the ingot to be produced. The coating can serve, among other things, to make it easier to remove the ingot from the mold.

According to the invention, the casting mold does not cool below the glass formation temperature of the solid glass-forming alloy at the contact surface with the melt for at least 5 seconds, in particular for at least 10 seconds and very particularly preferably for at least 30 seconds. Within the scope of the invention, a melt is also referred to after the liquid melt has been transferred to the casting mold, even if the solidification process has already started and the solid glass-forming alloy is partially or completely solid, as long as the glass transition temperature has not yet been fallen below.

In a preferred embodiment of the invention, the casting mold does not cool below the glass formation temperature of the solid glass-forming alloy at any point on the contact surface with the melt for the specified period. The determination of the glass formation temperature of the alloy is described under "Methods". In a preferred embodiment of the invention, the temperature of the mold at the contact surface with the melt for the aforementioned period is at least 10° C., in particular at least 20° C. and particularly preferably at least 40° C. or at least 80° C. above the glass formation temperature of the solid glass-forming Alloy.

To measure the temperature of the mold at the contact surface, a temperature measuring probe can be embedded in the mold in such a way that it reaches the contact surface of the mold with the melt and measures there. The temperature is preferably measured at half the length of the longest dimension of the ingot. The temperature of the mold before filling with the melt is preferably adjusted so that the temperature of the mold after casting at the contact surface with the melt for at least 5 seconds, in particular for at least 10 seconds and most preferably for at least 30 seconds after contact with the mold does not fall below the glass formation temperature of the alloy.

The mold is preferably heated prior to contact with the melt. The preferably set temperature of the mold directly before pouring the melt is at least 250°C, in particular at least 400°C and particularly preferably at least 500°C. The casting mold can be heated in an oven, for example. Alternatively, the mold can be actively heated, e.g. by electrical heating.

Preferably, no additional pressure substantially above standard atmospheric pressure is applied to the melt after the melt has been poured. In the context of the invention, “significantly above standard atmospheric pressure” can be understood to mean an overpressure of 1 bar or more.

In step c), the melt is cooled below the glass transition temperature of the alloy forming solid glass, with the ingot (20) being obtained. The melt is preferably cooled down to room temperature. The cooling rate in step c) is not further restricted according to the invention. In one possible embodiment, the melt is allowed to cool to room temperature without any additional action (heating or cooling). Alternatively, the melt can be actively cooled below the glass transition temperature to speed up the process.

By the method according to the invention, an ingot can be produced from a bulk glass-forming alloy which does not shatter during the production process. Furthermore, the method can produce an ingot that does not shatter when heated to the melting temperature of the alloy within 50 seconds or less. In particular, an ingot which does not shatter when dropped three times from a height of 30 cm onto a flat, horizontal steel surface can be produced. In particular, the method can be used to produce an ingot that does not have an amorphous layer on the surface. The absence of an amorphous layer can be determined with a light microscope.

ingot

In a further aspect, the invention relates to an ingot of a solid glass-forming alloy, the alloy having a critical casting thickness of at least 5 mm, and the ingot having an extent in all three spatial directions which is greater than the critical casting thickness, characterized in that that the ingot has a crystalline proportion of at least 90% by weight, in particular at least 95% by weight and particularly preferably at least 98% by weight, measured by DSC.

The critical casting thickness of the alloy is preferably at least 7 mm and in particular at least 10 mm. The ingot according to the invention can be produced using the method described herein will. In a preferred embodiment, the ingot according to the invention has no amorphous layer on the surface. In the context of the present invention, the term "no amorphous layer" can be understood as a layer which is no thicker than 200 μm, in particular no thicker than 100 μm and very particularly preferably no thicker than 50 μm. The absence of an amorphous layer can preferably lead to the reduction of internal stresses in the ingot. The absence of an amorphous layer on the surface of the ingot can be determined by optical microscopy (reflected light microscope). For this purpose, a cross-section of the ingot is created using a diamond saw. The cross-section is also called a metallurgical micrograph or cross-section. The absence of amorphous portions can be determined by the absence of a phase transition visible to the naked eye under the light microscope. Phase transitions can be identified in the light microscope as transitions of different colors or different contrasts. In this context, reference is made to Figures 1 to 3. illustration 1 shows a micrograph of a cross section through an ingot that has amorphous areas. These amorphous areas can be seen as a bright area towards the edge (arrow 1). The inner area of the examined ingot shows no bright areas (arrow 2). Contrast shows Figure 2 a micrograph of a cross-section through an ingot that does not have any amorphous areas. This can be recognized by the uniform material appearance without light spots. Figure 3 shows a metallurgical micrograph of the sample Figure 2 at higher magnification. The polycrystalline structures and their grain boundaries can be clearly seen there. Furthermore, it can be seen that the crystalline structure of the ingot according to the invention extends to the edge, which confirms the absence of an amorphous phase (eg in the circled area). If an amorphous phase were to occur, it would preferably form at the edge first, as this is where the cooling rates can potentially be highest.

In one embodiment, the total volume of the amorphous layer on the ingot can be 5% or less, in particular 3% or less. The crystallinity of the ingot can be measured using Differential Scanning Calorimetry (DSC). The ingot is preferably solid and has no cavities, such as air inclusions. According to the invention, the shape of the ingot is not limited. In one embodiment, the ingot may have a cylindrical shape. The cylinder diameter preferably has a value of at least 5 mm, in particular at least 15 mm and very particularly preferably at least 25 mm, in each case with the condition that the diameter is greater than the critical casting thickness of the solid glass-forming alloy. The length of the cylinder is preferably at least 3 cm.

In a further aspect, the invention relates to a method for producing three-dimensional components from metallic solid glasses by means of casting methods, in particular injection molding, using the ingot according to the invention of a solid glass-forming alloy.

During the production of the three-dimensional component by means of a casting process, such as injection molding, the ingot according to the invention is melted to form a homogeneous melt (30). The complete melting of the ingot (20) preferably takes no longer than 60 seconds, in particular no longer than 40 seconds and very particularly preferably no longer than 20 seconds, it being possible for the ingot to be heated without cracking.

Conventional ingots can typically only be melted much more slowly, otherwise they would shatter. This entails the disadvantages described above. The heating-up time for already known ingots of the same dimensions is typically in the range of 80 seconds. After the ingot (20) has been melted, the homogeneous melt (30) is poured, in particular injected, into the mold for a three-dimensional component (40). The casting mold for producing the three-dimensional component by means of the casting process is preferably dimensioned in such a way that it does not exceed the critical casting thickness of the alloy used at any point, since completely amorphous, three-dimensional components can be produced in this way. In particular, the ingot can be used to produce three-dimensional components that can be produced with a high throughput in an injection molding machine.

measurement methods X-ray diffraction (XRD)

The XRD measurements are carried out in accordance with DIN EN 13925-1:2003-07 and DIN EN 13925-2:2003-07. A cross section of the material to be examined is prepared with a diamond saw. The flat surface of the cross section is in the range of approx. 1 cm ² . The general measurement details used are summarized as follows: Diffraction: Bragg-Brentano; Detector: Scintillation Counter; Radiation: Cu _Kα 1.5406 Å; Source: 40kV, 25mA; Measurement method: reflection.

As an internal reference, the empty sample holder is measured first to determine the background signal. This background measurement is subtracted from all subsequent measurements of the samples to be examined.

Discrete diffraction signals in the diffractogram, if any, can be evaluated according to the Debye-Scherrer method using the Bragg equation. When visible from discrete, crystalline peaks above the statistical noise, a crystalline proportion of at least 5% by weight is assumed. If no sharp diffraction signals can be determined in the diffractogram, the crystalline proportion is below 5%.

DSC: measurement

The DSC measurements within the scope of the invention are carried out in accordance with DIN EN ISO 11357-1:2017-02 and DIN EN ISO 11357-3:2018-07. The sample to be measured in the form of a thin disc or foil (approx. 80 - 100 mg) is placed in the measuring device (NETZSCH DSC 404F1, NETZSCH GmbH, Germany). The heating rate is 20.0 K/min. Al ₂ O ₃ is used as the crucible material. The heat flow is measured against an empty reference crucible, so that only the thermal behavior of the sample is measured.

1. a) Die zu vermessende Probe wird mit der oben genannten Aufheizrate auf eine Temperatur T kurz unterhalb der Schmelztemperatur aufgeheizt (T=0,75^∗Tm) und der Wärmefluss gemessen. Die Messung ist abgeschlossen, wenn kein Wärmefluss im Zusammenhang mit Phasenübergängen mehr gemessen werden kann. Insbesondere wird die Messung beendet, wenn ein exothermes Signal in Zusammenhang mit dem Kristallisationsvorgang vollständig erfasst ist. In den hierin enthaltenen Beispielen wird z.B. von Raumtemperatur bis etwa 600°C gemessen.
2. b) Die Probe lässt man auf Raumtemperatur abkühlen.
3. c) Die Probe wird erneut mit derselben Aufheizrate auf dieselbe Temperatur aufgeheizt wie in Schritt a) und der Wärmefluss wird gemessen.
4. d) Die Messung aus Schritt c) wird von der Messung aus Schritt a) abgezogen, unter Erhalt der Messdifferenz. Aus der Differenzmessung wird die Kristallisationsenthalpie, falls vorhanden, durch Integralbildung bestimmt.

The measurement procedure is carried out according to the following steps:

1. a) The sample to be measured is heated to a temperature T just below the melting temperature (T=0.75 ^∗ Tm) at the heating rate mentioned above and the heat flow is measured. The measurement is complete when no more heat flow associated with phase transitions can be measured. In particular, the measurement is terminated when an exothermic signal associated with the crystallization process is fully detected. For example, in the examples contained herein, measurements are taken from room temperature to about 600°C.
2. b) The sample is allowed to cool to room temperature.
3. c) The sample is again heated to the same temperature at the same heating rate as in step a) and the heat flow is measured.
4. d) The measurement from step c) is subtracted from the measurement from step a) to obtain the measurement difference. From the differential measurement, the crystallization enthalpy, if any, is determined by integral formation.

1) Measurement of samples with a small amorphous content (e.g. ingot according to the invention)

Samples expected to be predominantly crystalline with little amorphous phase are measured according to the measurement method given above. The sample, for example from an ingot according to the invention, is heated in step a) to a temperature T=0.75 ^* Tm (75% of the melting point (Tm) in °C). If, after subtracting the reference measurement from step c), no heat flow can be determined in the range of the crystallization temperature, it is assumed that the sample is completely crystalline (measurement inaccuracy 5%). The complete crystallinity of the sample after undergoing the measurement procedure can be additionally confirmed by XRD, by the absence of broad, unspecific signals in the diffraction pattern that would indicate an amorphous phase. The amorphous content of samples with more than 5% by weight can be determined by comparing the crystallization enthalpy of the unknown sample with the value for the completely amorphous sample from DSC method 2) (see below).

2) Determination of the critical casting thickness

To determine the critical casting thickness, a sample of each of the cast cylinders is measured using DSC. As long as the diameter of the cylinder is below the critical casting thickness, the sample is completely amorphous before the start of the measurement and crystallizes during the DSC measurement in step a) of the measurement method. The crystallization enthalpy of the alloy is determined from the measurement of the completely amorphous material. The crystallization enthalpy is determined for all samples with increasing cylinder diameter. The crystallization enthalpy determined for samples whose cylinder diameter is below the critical casting thickness is constant within the measurement inaccuracy. As soon as the cylinder diameter exceeds the critical casting thickness, a smaller value is measured for the crystallization enthalpy in the DSC measurement of the sample than with the smaller diameters, since part of the material has already crystallized and this no longer happens within the DSC measurement. The critical casting thickness is determined as the cylinder diameter up to which the crystallization enthalpy is constant with increasing diameter.

3) glass transition temperature

1. a) Erwärmen auf eine Temperatur von 0,75^∗Tm mit einer Heizrate von 20K/min.
2. b) Abkühlen auf Raumtemperatur
3. c) Erwärmen auf die gleiche Temperatur wie in Schritt a) mit der gleichen Heizrate, und
4. d) Abkühlen auf Raumtemperatur.

In the present invention, glass transition temperature is measured according to ASTM E1365-03 as follows. The sample to be examined is placed in a crucible in a DSC device (NETZSCH DSC 404F1, NETZSCH GmbH, Germany). The system is heated and cooled according to the following scheme and the respective heat flow is measured in steps a) and c).

1. a) Heating to a temperature of 0.75 ^∗ Tm at a heating rate of 20K/min.
2. b) cooling to room temperature
3. c) heating to the same temperature as in step a) at the same heating rate, and
4. d) cooling to room temperature.

As a result of the experiment, the enthalpy versus temperature for the sample is obtained. In step a) the crystallization of the amorphous sample takes place. In step c), the thermal behavior of the already fully crystallized sample is recorded.

To determine the glass transition temperature, the measurement from step c) is subtracted from the measurement from step a). The resulting curve includes an endothermic transition at lower temperature and an exothermic peak at higher temperature. The signal at higher temperature corresponds to the crystallization process. The endothermic signal corresponds to the glass transition. To determine the glass transition temperature, a line tangent to the baseline is determined (by linear fitting) in front of the glass transition region. A second tangent is determined at the inflection point (corresponding to the peak time value of the first derivative) of the glass transition region. The temperature value at the intersection of the two tangents indicates the glass transition temperature (T _f according to AST; 1356-03).

examples

The individual components were melted under protective gas by means of inductive melting into a homogeneous alloy with the composition Zr _52.5 Ti ₅ Cu _17.9 Ni _14.6 Al ₁₀ . This alloy has a glass transition temperature of 403 °C. 80 g of the homogeneous alloy were brought to a temperature above the melting point of the alloy (805° C.) by means of inductive heating in a crucible. Table 1 shows the temperatures of the respective melt for the respective test. In each case, the mold was preheated in an oven to a temperature defined in Table 1. The respective homogeneous melt according to Table 1 was then poured into a casting mold. The mold had a cylindrical shape with an inner diameter of 19 mm. The temperature of the melt was continuously measured after filling the cylindrical mold. The measured values for the temperature of the melt after 10 seconds in the mold can be read in Table 1. <b>Table 1</b> example 1 2 3 4 5 T _melt [°C] 1050 1100 1200 1250 1350 T _mold [°C] 50 50 250 400 600 mold copper stole stole stole stole weight ratio 1:17 1:15 1:9 1:15 1:15 coating d. mold none B.N _{Y2O3 _} B.N _{Al2O3 _} T mold after 10s [°C] 150 150 410 420 about 550 quality of the ingot bad bad Good Good very good

Examples 1 and 2 in Table 1 are comparative examples, Examples 3-5 are examples according to the invention. The quality of the cast ingots was assessed according to the following criteria: Poor-quality cast parts already shatter while cooling in the mold. Good quality cast ingots will remain intact if heated to melting temperature within 50 seconds or less at a power of 5 kW. Very good quality ingots also withstand a drop test from a height of 30 cm onto a flat steel plate three times in a row without shattering. It is clear from Examples 1-5 that ingots in which the temperature of the melt was above the glass transition temperature after 10 seconds were significantly more robust than ingots in which the temperature of the melt was below.

• Abbildung 1 zeigt eine Aufnahme mit dem Lichtmikroskop, die den Querschnitt eines Ingots zeigt, der gemäß Beispiel 1 als Vergleichsversuch gefertigt wurde. Die hellen Bereiche im Querschnitt, die beispielhaft mit Pfeilen gekennzeichnet sind, zeigen amorphe Bereiche (Pfeil 1), die von dunkleren, kristallinen Bereichen umgeben sind (Pfeil 2). Weiterhin ist in Abbildung 1 zu erkennen, dass der Ingot gesprungen ist.
• Abbildung 2 zeigt eine Aufnahme mit dem Lichtmikroskop, die den Querschnitts eines Ingots zeigt, der gemäß Beispiel 4 gefertigt wurde. Der Querschnitt eines Ingots gemäß Beispiel 4 zeigt eine homogene Materialverteilung ohne helle Bereiche, die auf amorphe Phasen hindeuten würden.
• Abbildung 3 zeigt eine Vergrößerung der erfindungsgemäßen Probe aus Abbildung 2. Das Bild zeigt die multikristalline Struktur des Ingots bis in den Randbereich des Querschnitts.
• Abbildung 4 zeigt eine schematische Darstellung des Verfahrensverlaufs von den Einzelkomponenten der Massivglas-bildendenden Legierung (5) bis zum Bauteil aus metallischem Massivglas (40). Dabei werden die folgenden Stufen durchlaufen: Einzelkomponenten der Massivglas-bildendenden Legierung (5), homogene Schmelze (10), Ingot aus Massivglas-bildender Legierung (20), homogene Schmelze der Massivglas-bildenden Legierung (30) und Bauteil aus metallischem Massivglas (40).

Description of the pictures:

• illustration 1 FIG. 12 is an optical micrograph showing the cross section of an ingot fabricated according to example 1 as a comparative test. The bright areas in the cross section, which are marked with arrows as an example, show amorphous areas (arrow 1) surrounded by darker, crystalline areas (arrow 2). Furthermore, in illustration 1 to recognize that the ingot has cracked.
• Figure 2 FIG. 12 is an optical micrograph showing the cross-section of an ingot fabricated according to Example 4. FIG. The cross section of an ingot according to Example 4 shows a homogeneous material distribution without bright areas that would indicate amorphous phases.
• Figure 3 shows an enlargement of the sample according to the invention Figure 2 . The picture shows the multicrystalline structure of the ingot up to the edge area of the cross section.
• Figure 4 shows a schematic representation of the course of the process from the individual components of the solid glass-forming alloy (5) to the component made of metallic solid glass (40). The following stages are run through: individual components of the bulk glass-forming alloy (5), homogeneous melt (10), ingot of bulk glass-forming alloy (20), homogeneous melt of the bulk glass-forming alloy (30) and component made of metallic bulk glass (40 ).

Claims (12)

1. Method for producing an ingot of a solid-glass-forming alloy, having the steps of:

   a. providing a homogeneous melt of a solid-glass-forming alloy;

   b. casting the homogeneous melt into a casting mold, wherein the casting mold at the contact surface with the melt does not cool to below the glass formation temperature of the alloy for at least 5 seconds; and

   c. cooling the melt to below the glass transition temperature of the solid-glass-forming alloy, obtaining the ingot,
   wherein, after the melt has been cast, no additional pressure which is substantially above the standard atmospheric pressure is exerted on the melt.
2. Method according to claim 1, wherein the casting mold at the contact surface with the melt does not cool to below the glass formation temperature of the alloy for at least 10 seconds.
3. Method according to one of claims 1 or 2, wherein the solid-glass-forming alloy has a critical casting thickness of 5 mm or more, wherein
   the critical casting thickness, by means of DSC, is determined as described in the application text by processing the to-be-measured alloy in the light arc to form a homogeneous melt and subsequently casting it into a water-cooled, cylindrical, copper casting mold, wherein the mass of the copper casting mold is greater by at least a factor of 7 than the mass of the added melt of the alloy to be determined, wherein the temperature of the homogeneous melt prior to casting is at least 200 °C above the melting temperature, and wherein the temperature of the copper casting mold is 20 °C.
4. Method according to one of claims 1 through 3, wherein the dimension of the ingot in the three spatial directions is greater than the critical casting thickness as determined according to claim 3.
5. Method according to one of claims 1 through 4, wherein the ingot, relative to the weight, has a crystalline fraction of at least 90%, measured by means of DSC.
6. Method according to one of claims 1 through 5, wherein the ingot, relative to the weight, has a crystalline fraction of at least 95%, measured by means of DSC.
7. Method according to one of claims 1 through 6, wherein the casting mold is coated with a material selected from the group consisting of boron nitride, Y₂O₃, and aluminum oxide.
8. Method according to one of claims 1 through 7, wherein the ratio between the weight of the melt and the weight of the casting mold is 1:7 or less.
9. Method according to one of claims 1 through 8, wherein the temperature of the melt in step a) is at least 20% above the melting temperature, measured in degrees Celsius.
10. Ingot of a solid-glass-forming alloy, having a critical casting thickness of at least 5 mm, wherein the ingot has an extension in at least three spatial directions that is greater than the critical casting thickness, characterized in that the ingot has a crystalline fraction of at least 90 wt%, measured by means of DSC, wherein the critical casting thickness according to claim 3 is determined, and wherein the ingot does not have an amorphous layer on the surface.
11. Method for producing a three-dimensional component from a metallic solid glass by means of casting methods, characterized in that, for the casting method, an ingot (20) according to claim 10 is melted.
12. Method according to claim 11, wherein melting the ingot takes no longer than 60 seconds - in particular, no longer than 40 seconds.

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