Commercial brass powders are available in the simple brasses ranging from 95Cu-5Zn to 60Cu-40Zn and leaded versions of these brasses, and in modified brasses containing such elements as phosphorus, manganese and silicon. Nickel silver powders containing 64Cu-18Ni-18Zn and 64Cu-18Ni-16.5Zn-1.5Pb are also available on the commercial market. These powders are produced by atomizing alloy melts.
Optimum properties are attained by preheating to drive off lubricants and sintering in a cracked ammonia atmosphere. The P/M parts produced by such procedures have mechanical properties comparable with those of the corresponding cast alloys. Typical properties of representative brasses and nickel silvers are given in Table 4. These P/M alloys have moderate strength with good ductility.
Table 4. Typical Mechanical Properties of Brass and Nickel Silver P/M Compacts Pressed at 30 Tons/Sq. In. (414 MPa)
% in 1 in.
Source: Data from New Jersey Zinc Company and U.S. Bronze Powders, Inc.
Next to bronze bearings, the brasses and nickel silvers are the most widely used materials for structural P/M parts. Examples of the many applications are hardware for latch bolts and cylinders for locks; shutter components for cameras; gears, cams and actuator bars in timing assemblies; small generator drive assemblies; and decorative trim and medallions.