Effect of Phosphorus on the Embrittlement of Copper-Nickel Alloys by Mercury

Phosphorus is shown to have a marked effect on the susceptibility of copper-nickel alloys to mercury embrittlement. If phosphorus is absent, the alloys have very little ductility in the presence of mercury; at intermediate levels, an increase in elongation is noted and the susceptibility also becomes a function of heat treatment; at high levels, the alloys are completely immune even when quenched from a high annealing temperature. The amount of phosphorus required depends on the nickel content as well as on other alloying elements. The effect is unique to copper-nickel alloys and does not occur in other types of copper alloys.