Fatigue strength of a Au-Pd alloy/585 solder combination

The S-N diagram (applied stress vs. cycles to failure) for the gold-palladium alloy/585 solder combination was generated. Au-Pd alloy specimens were cast, prepared for soldering, and joined with 585 solder. After milling and polishing of the joint, testing was carried out in a specially designed machine. This device loaded the cantilevered test specimen in a unidirectional mode at a rate of 70 strokes per minute. The applied tensile stress ranged between 294.2 and 686.5 MPa. Three specimens were cycled for each stress level until fracture occurred. The number of fatigue cycles to failure ranged from one cycle (stress level, 686.5 MPa) to 4.83 x 10(6) cycles (stress level, 294.2 MPa). On a logarithmic scale, the relationship between the applied stress and the number of cycles to failure was linear. Under the present (ideal) experimental conditions, the Au-Pd/585 solder combination behaved favorably on the high-cycle end of the diagram. However, no definite endurance limit could be detected within the stress range examined.