EFFECT OF ALUMINA STRENGTHENING PARTICLES ON BRAZED JOINTS OF GLIDCOPAL-15 COPPER ALLOY

Brazed joints of the alumina dispersion-strengthened copper alloy were developed using resistance heating brazing with BCuP-3 braze alloy. E xperimental results show that tensile strength and fatigue properties are a function of the brazing process temperature cycle. Maximum tensi le and fatigue properties can be obtained by choice of an optimal braz e time and temperature. However, in both tensile and fatigue tests the brazed joints exhibited low ductility. Metallography of the fractured tensile and fatigue samples showed that cracks always initiated in an d propagated along the interface between the transition layer and the braze metal. EDS analysis across the joint showed that P diffused very quickly into base metal along grain boundaries. A strong Al peak (ass ociated with the detection of Al2O3) was found that corresponded with the transition layer. Fractography showed an intergranular fracture pa ttern across this transition zone indicating that the observed segrega tion of alumina particles reduces the ductility of this region.