Production of metallic glass objects by melt deposition

An apparatus for forming a metallic glass tube, the apparatus comprising:

• an interior tubular substrate of circumference wi;
• and
• an exterior tubular substrate of circumference wo, where wo>wi;
• 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 Vo;
• 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 wo or wi 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.

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 Vo;
• 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 Vo;
• 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·τcr), where a is the thermal diffusivity of a melt and τcr 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 Vo is in the range of 0.1α/t to 10000α/t;
• and
• wherein the deposition rate Q is within 20% of the product (Vo×t×w).

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 wi and wo, where wo>wi, along either wo or wi,
• 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 Vo;
• cooling the deposited molten alloy with at least one of the tubular substrates;
• wherein the gap thickness t is less than √(α·τcr), where a is the thermal diffusivity of a melt and τcr is the minimum crystallization time of the metallic glass alloy;
• wherein one of the two substantially concentrically arranged tubular substrates 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 Vo is in the range of 0.1α/t to 10000α/t;
• and
• wherein the deposition rate Q is within 20% of the product (Vo×t×w), where w is a mean tube circumference given by w=(wo+wi)/2.