MELT OVERHEATING METHOD FOR IMPROVED TOUGHNESS AND GLASS-FORMING ABILITY OF METALLIC GLASSES

• US 20140202596A1
• Filed: 01/22/2014
• Published: 07/24/2014
• Est. Priority Date: 01/22/2013
• Status: Abandoned Application

• Current Assignee: Apple Inc.
• Original Assignee: Glassimetal Technology Inc.
• Inventors: NA, Jong Hyun, FLOYD, Michael, LEE, David S., DEMETRIOU, Marios D., JOHNSON, William L., GARRETT, Glenn
• Application Number:
  US14/161,434
• Publication Number:
  US 20140202596A1
• Time in Patent Office: Days
• US Class Current: 148/538
• CPC Class Codes: B22D 27/04 Influencing the temperature of the metal, e.g. by heating or cooling the mould
• CPC Class Codes: B22D 46/00 Controlling, supervising, not restricted to casting covered by a single main group, e.g. for safety reasons controlling or regulating in general G05
• CPC Class Codes: C22C 1/11 Making amorphous alloys
• CPC Class Codes: C22C 33/003 making amorphous alloys
• CPC Class Codes: C22C 45/00 Amorphous alloys making amorphous non-ferrous alloys C22C1/11
• CPC Class Codes: C22C 45/001 with Cu as the major constituent
• CPC Class Codes: C22C 45/003 with one or more of the noble metals as major constituent
• CPC Class Codes: C22C 45/005 with Mg as the major constituent
• CPC Class Codes: C22C 45/02 with iron as the major constituent
• CPC Class Codes: C22C 45/04 with nickel or cobalt as the major constituent
• CPC Class Codes: C22C 45/08 with aluminium as the major constituent
• CPC Class Codes: C22C 45/10 with molybdenum, tungsten, niobium, tantalum, titanium, or zirconium or Hf as the major constituent

Abstract

A method of forming a bulk metallic glass is provided. The method includes overheating the alloy melt to a temperature above a threshold temperature, T_tough, associated with the metallic glass demonstrating substantial improvement in toughness compared to the toughness demonstrated in the absence of overheating the melt above T_liquidus, and another threshold temperature, T_GFA, associated with the metallic glass demonstrating substantial improvement in glass-forming ability compared to the glass-forming ability demonstrated in the absence of overheating the melt above T_liquidus. After overheating the alloy melt to above T_tough and T_GFA, the melt may be cooled and equilibrated to an intermediate temperature below both T_tough and T_GFA but above T_liquidus, and subsequently quenched at a high enough rate to form a bulk metallic glass.

Claims

1. A method of forming a bulk metallic glass, comprising:

melting an alloy by heating the alloy to a temperature above the liquidus temperature, T_liquidus;

overheating the alloy melt to an overheating temperature above a threshold temperature, T_tough, associated with the metallic glass demonstrating increased toughness compared to the toughness demonstrated by heating the melt just above T_liquidus and quenching the melt to form a bulk metallic glass.

2. The method of claim 1, wherein the temperature of the overheated alloy melt is also above a threshold temperature, T_GFA, associated with the metallic glass demonstrating increased critical rod diameter compared to the critical rod diameter demonstrated by heating the melt just above T_liquidus.

3. The method of claim 2, wherein T_tough is greater than T_GFA.

4. The method of claim 1, wherein the toughness of the metallic glass is at least 25% greater than the toughness of the metallic glass formed in the absence of overheating above T_liquidus.

5. The method of claim 1, wherein the toughness of the metallic glass is at least 50% greater than the toughness of the metallic glass formed in the absence of overheating above T_liquidus.

6. The method of claim 2, wherein the critical rod diameter is at least 25% greater than the critical rod diameter attained in the absence of overheating above T_liquidus.

7. The method of claim 2, wherein the critical rod diameter is at least 50% greater than the critical rod diameter attained in the absence of overheating above T_liquidus.

8. The method of claim 1, further comprising

cooling the alloy melt to an intermediate temperature below T_tough and T_GFA but above T_liquidus,

equilibrating the alloy melt at the intermediate temperature, and

quenching the alloy melt to form the metallic glass.

9. The method of claim 1, wherein the alloy is selected from a Zr-based alloy, Ti-based alloy, Al-based alloy, Mg-based alloy, Ce-based alloy, La-based alloy, Y-based alloy, Fe-based alloy, Ni-based alloy, Co-based alloy, Cu-based alloy, Au-based alloy, Pd-based alloy, and Pt-based alloy.

10. The method of claim 1, wherein the alloy is represented by the formula X_100-a-bY_aZ_b

where:

X is Ni, Fe, Co, Pd, Pt, Au, Cu or combinations thereof;

Y is Cr, Mo, Mn, Nb, Ta, Ni, Cu, Co, Fe, Pd, Pt, Ag or combinations thereof;

Z is P, B, Si, Ge, C or combinations thereof;

a is between 2 and 45 at %; and

b is between 15 and 25 at %.

11. The method of claim 1, wherein the alloy is represented by the formula X_100-a-bY_aZ_b, wherein:

X is Ni, Fe, Co or combinations thereof,

Y is Cr, Mo, Mn, Nb, Ta or combinations thereof,

Z is P, B, Si, Ge or combinations thereof,

a is between 5 and 15 at %, and

b is between 15 and 25 at %.

12. The method of claim 1, wherein the alloy melt is heated by a process selected from inductive heating, resistively heating (in a furnace), a plasma arc heating, and joule heating.

13. The method of claim 1, wherein the melt is held in a crucible comprising a material selected from fused or crystalline silica, a ceramic, alumina, zirconia, graphite, and a water-cooled hearth made of copper or silver.

14. A method of forming a shaped metallic glass article, comprising:

melting a metallic glass forming alloy by heating the alloy to a temperature above the liquidus temperature of the alloy, T_liquidus.

overheating the alloy melt to an overheating temperature above both a threshold temperature, T_tough, associated with the metallic glass demonstrating increased toughness compared to the toughness demonstrated by heating the melt just above T_liquidus, and a threshold temperature, T_GFA, associated with the alloy demonstrating an increase in critical rod diameter compared to the critical rod diameter demonstrated by heating the melt just above T_liquidus; and

quenching the alloy melt to form the alloy melt into a shaped metallic glass article.

15. The method of claim 14, further comprising cooling and equilibrating the alloy melt to an intermediate temperature below T_tough and T_GFA but above T_liquidus;

and quenching the alloy melt to form a shaped metallic glass article.

16. The method of claim 14, wherein the toughness of the metallic glass is at least 25% greater than the toughness of the metallic glass formed in the absence of overheating above T_liquidus.

17. The method of claim 14, wherein the toughness of the metallic glass is at least 50% greater than the toughness of the metallic glass formed in the absence of overheating above T_liquidus.

18. The method of claim 14, wherein the critical rod diameter is at least 25% greater than the critical rod diameter attained in the absence of overheating above T_liquidus.

19. The method of claim 14, wherein the critical rod diameter is at least 50% greater than the critical rod diameter attained in the absence of overheating above T_liquidus.

20. The method of claim 14, wherein the alloy comprises a material selected from a group consisting of a Zr-based alloy, Ti-based alloy, Al-based alloy, Mg-based alloy, Ce-based alloy, La-based alloy, Y-based alloy, Fe-based alloy, Ni-based alloy, Co-based alloy, Cu-based alloy, Au-based alloy, Pd-based alloy, and Pt-based alloy.