The Microplastic Behavior of Several Precious Metal Electrical Contact Alloys

Measurements have been made of the microyield and transient creep behavior of three commonly used precious alloy spring contact materials. These tests were done to determine how resistant the alloys were to contact force loss while stored for long times in a stressed condition. The alloys studied were Neyoro G, Paliney 7, and Neyoro 28A. Test temperatures from -58°F(223K) to 212°F(373K) and stresses up to the proportional limit were studied. Neyoro G and Paliney 7 in the age hardened condition were both found to be very resistant to microplastic deformation. Even for stresses equaling the proportional limit, contact force relaxation over several years is predicted to be only a few percent. Neyoro 28A is much less resistant to deformation.