US-12618124-B2 - Oxidation resistant high conductivity copper alloys

Abstract

A micro-alloyed copper powder was produced using gas atomization reaction synthesis, with the alloy preferably comprising Cu-0.3Zr-0.15Ag wt. %. The novel copper alloy improves the manufacturability of copper in powder bed fusion manufacturing processes by minimizing or avoiding the prior art problems associated with oxidation of the copper precursor used in additive manufacturing. Advantageously, the provided copper alloy powder maintains the high electrical conductivity of copper while addressing the prior art oxidation issue.

Inventors

• Christian Gentry Miles Barr
• Timothy Prost

Assignees

• HONEYWELL FEDERAL MANUFACTURING & TECHNOLOGIES, LLC

Dates

Publication Date

20260505

Application Date

20221215

Claims (9)

1. 1 . A copper alloy comprising: about 0.26% by weight to about 0.34% by weight Zr; and about 0.11% by weight to about 0.19% by weight Ag, with the balance being Cu and optionally incidental impurities, wherein, when present, said incidental impurities are present in an amount of 0.001% by weight or lower, said % by weight being based upon the weight of said copper alloy, said alloy having at least one of: (i) an ultimate tensile strength of about 230 MPa to about 250 MPa; or (ii) a yield strength of about 130 MPa to about 159 MPa; and said alloy having an electrical conductivity of at least 94% IACS.
2. 2 . The copper alloy of claim 1 , wherein said alloy comprises about 99.47% by weight to about 99.63% by weight Cu.
3. 3 . The copper alloy of claim 1 , wherein said alloy consists of said Cu, said Zr, said Ag, and optionally said incidental impurities in an amount of 0.001% by weight or lower, when present in said alloy.
4. 4 . The copper alloy of claim 1 , wherein said alloy has a % elongation of about 25% or more.
5. 5 . The copper alloy of claim 1 , said alloy comprising about 0.28% to about 0.30% by weight Zr and about 0.14% to about 0.15% by weight Ag, with the balance being Cu and optionally incidental impurities.
6. 6 . The copper alloy of claim 1 , said alloy having an electrical conductivity of at least 95% IACS.
7. 7 . A copper alloy comprising: about 0.26% by weight to about 0.34% by weight Zr; and about 0.11% by weight to about 0.19% by weight Ag, with the balance being Cu and optionally incidental impurities, wherein, when present, said incidental impurities are present in an amount of 0.001% by weight or lower, said % by weight being based upon the weight of the copper alloy, said alloy having a % elongation of about 25% or more, said alloy having an ultimate tensile strength of about 230 MPa to about 250 MPa and an electrical conductivity of at least 94% IACS.
8. 8 . The copper alloy of claim 7 , said alloy comprising about 0.28% to about 0.30% by weight Zr and about 0.14% to about 0.15% by weight Ag, with the balance being Cu and optionally incidental impurities.
9. 9 . The copper alloy of claim 7 , said alloy having an electrical conductivity of at least 95% IACS.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 63/413,083, filed Oct. 4, 2022, entitled OXIDATION RESISTANT HIGH CONDUCTIVITY COPPER ALLOYS, the entirety of which is incorporated by reference herein. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with Government support under Contract No. DE-NA-0002839, awarded by the United States Department of Energy/National Nuclear Security Administration and Contract No. DE-AC02-07CH11358. The Government has certain rights in the invention. BACKGROUND Field The present disclosure relates to copper alloys useful in powder bed fusion additive manufacturing processes. DESCRIPTION OF RELATED ART The fabrication of copper components exhibiting high electrical or thermal conductivity using powder bed fusion (PBF) additive manufacturing (AM) presents several distinctive processing challenges. The high thermal conductivity of copper and the comparatively low heat transfer through the powder establishes a narrow process window. Excessive oxidation during normal use and reuse of powder feedstock and its effect on the feasible process window have posed a practical problem for achieving consistent materials properties as well. Pure copper readily forms a non-passivating surface oxide (Cu2O) when exposed to air or moisture. This typically occurs during powder handling, recycling, and/or exposure to the low partial pressures of oxygen present within the build chamber atmosphere during PBF AM. Maintaining a consistent oxygen content throughout the powder production and AM process is complicated by the high specific surface area of the AM powder feedstock as well as the distribution of powder sizes. The thickness of oxide on pure copper powder may only be a few nanometers, but it contributes significantly to the bulk composition. Additionally, significant oxidation of pure copper feedstock powders can occur after several reuse cycles for EB-PBF, and storage of Cu-containing powders in nominal storage conditions can result in a four-fold increase in oxygen content over a 12-month period. The solubility of oxygen in copper is low and during the processing of copper, a eutectic composition of copper and oxygen solidifies and segregates to the grain boundaries as Cu2O precipitates. To a limited extent, the thermal and electrical properties of copper are susceptible to degradation caused by the effects of contamination by oxygen. Since the Cu2O is incoherent, the deleterious effects on thermal and electrical properties are relatively small up to a composition of about 500-600 wt. ppm, however, the influence of oxygen content beyond this range adversely affects the ductility and ultimate tensile strength of PBF AM processed materials and poses a risk for embrittlement if downstream hydrogen brazing processes are required. Further, from the standpoint of process stability and consistency, powder surface oxides can significantly alter the thermo-physical properties of the feedstock and, consequently, the feasible AM process window. Several alternatives for addressing this challenge have been investigated either directly or indirectly, however, none have been successful in overcoming the above problems. SUMMARY The present disclosure is broadly concerned with a copper alloy, structures formed with a copper alloy, and methods of forming a copper alloy powder. In one embodiment, the copper alloy comprises about 0.26% by weight to about 0.34% by weight Zr and about 0.11% by weight to about 0.19% by weight Ag, with the balance being Cu and optionally incidental impurities. The % by weight is based on the weight of the copper alloy. In another embodiment, the disclosure provides a three-dimensional structure formed by the additive manufacturing of an alloy comprising Cu, Zr, and Ag. In yet another embodiment, a method of forming a three-dimensional structure is provided. This method comprises additive manufacturing an alloy comprising Cu, Zr, and Ag. In a further embodiment, a method of forming a copper alloy powder is provided. The method comprises gas atomizing Cu, Ag, and Zr so as to form the copper alloy powder. The copper alloy powder comprises about 0.26% by weight to about 0.34% by weight Zr and about 0.11% by weight to about 0.19% by weight Ag, with the balance being Cu and optionally incidental impurities. The % by weight is based on the weight of the copper alloy powder. BRIEF DESCRIPTION OF THE DRAWINGS The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. FIG. 1 is a photograph of a typical array of copper alloy samples fabricated by electron beam powder bed fusion, as described in Example 1, Part 3; FIG. 2 is a schematic depiction of the layout of blocks on the start plate an