Production of metallic glass objects by melt deposition

Patent metadata

Field	Value
Publication number	US-10589349-B2
Application number	US-201615085614-A
Country	US
Kind code	B2
Filing date	Mar 30, 2016
Priority date	Mar 30, 2015
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

Methods and apparatus for forming high aspect ratio metallic glass objects, including metallic glass sheets and tubes, by a melt deposition process are provided. In some methods and apparatus a molten alloy is deposited inside a channel formed by two substrates moving relative to each other, and shaped and quenched by conduction to the substrates in a manner that enables the molten alloy to vitrify without undergoing substantial shear flow.

First claim

The invention claimed is:

1. An apparatus for forming a metallic glass object, the apparatus comprising:
a first substrate; and
a second substrate separated from the first substrate by a gap of thickness t, the first substrate and the second substrate configured to move relative to each other at a velocity V o ;
the first substrate and the second substrate and the gap configured to form a channel having a thickness t and width w defined by an overlapping cross section of the first substrate and the second substrate perpendicular to a direction of the velocity V o ;
a melt reservoir configured to contain a molten alloy capable of forming the metallic glass object;
a nozzle configured to be in fluid communication with the melt reservoir and configured to extract the molten alloy along the overlapping cross section of the first substrate and second substrate and deposit the molten alloy at a constant deposition rate into the channel at a contact temperature with each substrate;
wherein the first substrate has a thermal conductivity of at least 10 W/m-K,
wherein the second substrate has at least one of the following: a contact angle with the molten alloy capable of forming the metallic glass object of more than 90° at a contact temperature, and a surface roughness in a contact surface with a melt having an average surface asperity height of less than 1 μm;
and/or at least one of the first substrate and the second substrate is configured to cool the molten alloy.

2. The apparatus of claim 1 , wherein the first substrate and the second substrate have a plate shape.

3. The apparatus of claim 1 , wherein the thickness t does not vary by more than 10% at any two locations along the gap.

4. The apparatus of claim 1 , wherein the constant deposition rate is achieved by means of an actuator, wherein the actuator comprises a plunger drive having cross sectional area A p moving at a velocity V p , wherein V p is within 50% of the value (V o ×r×w)/A p .

5. The apparatus of claim 1 , wherein the first substrate is disposed along an outer edge of the nozzle.

6. The apparatus of claim 1 , wherein the first substrate is thermally isolated from the nozzle.

7. The apparatus of claim 1 , wherein the first substrate is configured to be held at a temperature lower than the temperature of the nozzle.

8. An apparatus for forming a metallic glass tube, the apparatus comprising:
an interior tubular substrate of circumference w i ; and
an exterior tubular substrate of circumference w o , where w o >w i ;
the interior tubular substrate and the exterior tubular substrate are arranged concentrically with the interior substrate inside the exterior substrate such that they are separated by gap t; and
the interior tubular substrate and the exterior tubular substrate are configured to move relative to each other at a velocity V o ;
a melt reservoir configured to contain a molten alloy and disposed in fluid communication with the gap;
where the gap is a tubular channel for a molten alloy capable of forming metallic glass to be deposited after being extracted along either w o or w i and deposited at a constant deposition rate between the interior tubular and exterior tubular substrates at a contact temperature with each substrate;
at least one of the interior and exterior tubular substrates has a thermal conductivity of at least 10 W/m-K,
at least one of the interior and exterior tubular substrates has one of the following: a contact angle with the molten alloy capable of forming the metallic glass object of more than 90° at a contact temperature, and a surface roughness in a contact surface with a melt having an average surface asperity height of less than 1 μm;
and at least one of the interior and exterior substrates is configured to cool the molten alloy.

9. A method of forming a metallic glass object, the method comprising:
heating an alloy capable of forming a metallic glass to form a molten alloy; depositing the molten alloy at a constant deposition rate Q in a gap of thickness t separating a first substrate and a second substrate, where the first and second substrates are configured to move relative to each other at a velocity V o ; and
cooling the extracted molten alloy with at least one of the first substrate and the second substrate;
wherein the deposition is along an overlapping cross section between the first substrate and second substrate having width w that is perpendicular to the direction of V o ;
wherein temperatures of the first substrate and second substrate are below a nose temperature of the metallic glass,
wherein the gap thickness t is less than √(α·τ cr ), where a is the thermal diffusivity of a melt and τ cr is the minimum crystallization time of the metallic glass alloy;
wherein the second substrate has at least one of the following: a contact angle with the molten alloy capable of forming the metallic glass object of more than 90° at a contact temperature, and a surface roughness in a contact surface with the melt having an average surface asperity height of less than 1 μm;
wherein the relative velocity V o is in the range of 0.1α/t to 10000α/t; and
wherein the deposition rate Q is within 20% of the product (V o ×t×w).

10. The method of claim 9 , wherein the deposition rate Q is in the range of 0.1αw to 10000αw.

11. The method of claim 9 , wherein the relative velocity V o is in the range of 0.1 mm/s to 10 m/s.

12. The method of claim 9 , wherein the deposition rate Q is in the range of 10 −10 m 3 /s to 10 −2 m 3 /s.

13. The method of claim 9 , wherein the gap thickness t is less than a critical casting thickness of the metallic glass alloy.

14. The method of claim 9 , wherein the gap thickness t is in the range of 0.1 mm to 1 mm.

15. The method of claim 9 , wherein a shearing rate of the molten alloy between the substrates is less than the ratio V o /t.

16. The method of claim 9 , wherein a skin friction coefficient at an interface between the melt and a contact surface of at least one of the first substrate and the second substrate is less than η/ρV o t, where η is the melt viscosity and ρ is the melt density.

17. The method of claim 9 , wherein at least one of the first substrate and the second substrate is held at a temperature lower than a glass transition temperature of the metallic glass.

18. The method of claim 9 , wherein a melt temperature of the alloy prior to being deposited is heated to a temperature of at least 100° C. higher than T L .

19. The method of claim 9 , wherein a temperature of the molten alloy between the first and second substrates reaches a steady state.

20. A method for forming a metallic glass tube, the method comprising:
heating an alloy capable of forming a metallic glass to form a molten alloy;
depositing the molten alloy at a deposition rate Q in an annular gap of thickness t separating two substantially concentrically arranged tubular substrates of circumferences w i and w o , where w o >w i , along either w o or w i ,
wherein a temperature of the tubular substrates is below a nose temperature of the metallic glass;
wherein the tubular substrates are configured to move relative to each other at a velocity V o ;
cooling the deposited molten alloy with at least one of the tubular substrates;
wherein the gap thickness t is less than √(α·τ cr ), where a is the thermal diffusivity of a melt and τ cr is the minimum crystallization time of the metallic glass alloy;
wherein one of the two substantially concentrically arranged tubular substrates has at le

Assignees

• Glassimetal Tech Inc
• Apple Inc

Inventors

• Demetriou Marios D
• Schramm Joseph P
• Kaltenboeck Georg
• Johnson William L

Classifications

• B22D11/001 Primary

  of specific alloys · CPC title

• C22C45/00

  Amorphous alloys (making amorphous non-ferrous alloys C22C1/11) · CPC title

• B22D11/055

  Cooling the moulds {(B22D11/04 takes precedence)} · CPC title

• B22D23/00 Primary

  Casting processes not provided for in groups B22D1/00 - B22D21/00 (making metallic powder by casting B22F9/08; alumino-thermic welding B23K23/00; remelting metals C22B9/16) · CPC title

• B22D11/059

  Mould materials or platings · CPC title