Alloy Development and Characterization Services (for United States Currency Applications)

Published

November 6, 2015

Author(s)

Eric Lass, Mark R. Stoudt, Tony Ying, Carelyn E. Campbell

Abstract

Due to the rising cost of materials, the US Mint is seeking alternative coinage alloys to reduce the production cost for US nickels, dimes, and quarters. Commercial C71300, a 0.75 copper, 0.25 nickel by mass cupronickel alloy (in shorthand form Cu-25Ni) is currently used for the 5-cent coin and as a cladding material for the 10-cent and 25-cent coins. The cost to produce a 5-cent coin is approximately 7.5 cents. In response, Congress has tasked the US Mint to reduce the cost to produce the 5, 10, and 25-cent coins by 25 to 40 percent without changing its current processing and production capabilities. As part of this effort, the US Mint and the NIST Materials Science and Engineering Division (MSED) established an Interagency Agreement (IA) in June 2014 to develop a series of new, lower-cost coinage alloys. These new alloys are based on current nickel-silver alloys (also referred to as German-silver), which consist of copper, nickel, and zinc. Specifically, NIST agreed to develop three prototype alloys to replace the current coinage materials. The prototypes were: 1. An alloy based on C77000, a nickel-silver based alloy with a nominal composition of Cu-0.18Ni-0.27Zn mass fraction. This alloy is the first-step in the cost reduction strategy with an anticipated reduction in the production cost of the monolithic 5-cent coin of approximately 22 percent. 2. An alloy based on commercial C99750, an alloy comprised primarily of Cu, Ni, Zn, and Mn. Because it has a higher Zn content than C77000, this alloy could further reduce the production cost of the 5-cent coin to realize a total reduction of approximately 40 percent over the original cost. 3. An alloy based on a second modification of commercial C99750 that will be used as a cladding material for the 10-cent and 25-cent coins.

Citation

NIST Interagency/Internal Report (NISTIR) - 1404-642-01

Report Number

1404-642-01

NIST Pub Series

NIST Interagency/Internal Report (NISTIR)

Pub Type

NIST Pubs

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Keywords

Cu alloys, CALPHAD modeling, electrical conductivity, materials design

Citation

Lass, E. , Stoudt, M. , Ying, T. and Campbell, C. (2015), Alloy Development and Characterization Services (for United States Currency Applications), NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=919454 (Accessed April 25, 2024)