Copper-Based Alloys Containing Carbon

Copper-based alloys used for casting plumbing components typically contain lead, which is insoluble in copper (Cu). Lead is considered necessary to "plug" microporosity formed during solidification as well as improve machinability. While leaded versions of brass and bronze alloys are preferred for virtually all components requiring significant machining, plumbing component manufacturers are under increasing pressure to remove lead from valves and fittings, whether cast or wrought, due to possible contamination.

Previously, Purdue University researchers developed copper-manganese (Cu-Mn) alloys, which have many of the same benefits as copper-lead alloys, but without the negative side effects. The researchers have now developed Cu-Mn alloys containing carbon based on compositions near the congruent (minimum) melting point at 870 degrees Celsius and 32 wt% manganese. The low melting temperature and narrow freezing range of these alloys compared to other copper alloys make them especially well-suited for complex shape casting, e.g., plumbing valves and fittings, due to their high castability. The high concentration and low cost of manganese relative to copper and other alloying elements commonly used in copper alloys make these alloys intrinsically low-cost. Furthermore, the amount of carbide in the alloy and the resultant microstructure can be controlled to tailor strength, hardness, and machinability for the required application.

Advantages:

-Nontoxic and environmentally friendly

-Lower cost compared to lead-based alloy

-High strength and castability

-Controlled strength and machinability

Potential Applications:

-Plumbing manufacturing

TRL: 7

Intellectual Property:

Keywords: Copper-manganese alloys, Cu-Mn, lead-free copper alloys, plumbing components, complex shape casting, high castability, nontoxic alloy, low-cost copper alloy, carbide microstructure, machinable brass alternative