Mechanical Design Limits for a Wrought Cu-15Ni-8Sn Spinodal Alloy

High performance copper alloys are the materials of choice for highly loaded rotating and sliding bearings. The Cu-15Ni-8Sn system is relatively modern, invented in the 1970's, and strengthened by a spinodal transformation that achieves high strength with usable engineering ductility. The development of novel casting technology combined with large scale hot working is largely credited with the ability to produce the large rods, bars, tubes and plate product forms needed by the aerospace industry. Wrought rod, bar and tube properties have been statistically assessed and form the basis for design limits listed in the most current MMPDS (Metallic Materials Properties Development and Standardization) handbook as well as AMS 4596A.

The microstructure and metallurgical behavior of Cu-15Ni-8Sn spinodal alloy (C72900 TX00) will be discussed in this paper. Pin bearing, compression and shear strengths as well as physical properties will be described. Fracture characteristics of the microstructure will also be illustrated. SEM and optical metallography show the predominant mechanism for crack movement to be transgranular for highly constrained deformation zones and predominantly intergranular in general. At high magnification the grain boundary fractures show much local ductility.