10% Chrome Copper is a copper-chromium master alloy with a nominal composition of 90% Cu and 10% Cr. The high chromium content relative to the C81500 engineering alloy makes this a purpose-formulated addition master designed for efficient controlled chromium additions to copper, brass, and bronze heats where chromium is added for corrosion resistance, grain refinement, and improved mechanical properties. Chromium additions to copper alloys are made primarily to improve corrosion resistance in industrial atmospheres and mildly aggressive media, to increase elevated-temperature strength, and as a grain refiner for improved as-cast microstructure. In copper-nickel alloys chromium additions improve resistance to sulfide corrosion. The master alloy form provides a convenient accurately weighable addition with lower chromium content than elemental chromium which dissolves too slowly in copper melts at practical pouring temperatures. Supplied in 2-10 lb ingots for foundry addition use.
Available Forms
2-10 Ingot
Product Code
4906
Technical Info
Thermal Properties
Melting Point (Solidus)1,969°F (1,076°C)
Melting Point (Liquidus)2,444°F (1,340°C)
Physical Properties
Density (imperial)0.315 lbs/in³
Density (metric)8.72 g/cm³
Primary ElementsCu · Cr
Lead FreeYes
Key Features
Master Alloy for Cr AdditionsCorrosion Resistance ImproverGrain RefinerControlled Addition
Solubility Note
Dissolves readily in molten copper and copper alloy heats; add at melt temperature with stirring to ensure complete dissolution before pouring.
Nominal Composition
90% Cu
10% Cr
Frequently Asked Questions
Common technical inquiries regarding 10% Chrome Copper
Elemental chromium has a melting point of 3465F — far above practical copper casting temperatures — and dissolves extremely slowly in molten copper without pre-alloying. The 10% Chrome Copper master alloy pre-dissolves chromium into a copper matrix that melts near standard copper casting temperatures allowing controlled rapid chromium addition to the melt with accurate charge calculation. The master alloy form also reduces the risk of localized chromium-rich regions forming in the casting from undissolved elemental additions.
To achieve a target chromium level of X% in a given heat charge 10 times X% of the heat weight as 10% Chrome Copper master alloy. For example to add 0.5% Cr to a 100 lb heat charge 5 lbs of 10% Chrome Copper. Account for approximately 10-15% chromium loss to oxidation during the addition and melt hold period. Verify final chromium content by spectrographic analysis before pouring critical components.
Chromium in solid solution significantly reduces copper's electrical conductivity — at 0.5% Cr in solution conductivity drops to approximately 45% IACS from pure copper's 100% IACS. However when the chromium is precipitation hardened out of solution by aging heat treatment after cold working conductivity recovers to 80-85% IACS while retaining the strength benefit. For applications requiring both high conductivity and strength the copper-chromium system must be processed with solution anneal, cold work, and aging.
2% boron copper master alloy for deoxidizing pure copper or grain refining brass alloys. Forms: polished shot; unpolished shot; waffle; and 4-5 oz pieces.
Virgin grade silicon copper master alloy (90% Cu, 10% Si) for fluidity improvement and deoxidation in copper alloys and jewelry casting. Lumps and slabs.
