RHODIUM SEGREGATION IN DILUTE SILVER RHODIUM ALLOYS

Segregation of Rh in Ag-based alloys has been studied using the pertur bed angular correlation of gamma-rays emitted in the nuclear decay of radioactive In-111. The formation of impurity complexes, consisting of an In-111 probe atom and one or more Rh atoms, was observed as a func tion of annealing time and temperature. Rhodium atom aggregation start s at about 600 K. From the fraction of In-111 bound to isolated Rh ato ms the solute rhodium atom concentration was determined. It increases with the nominal alloy concentration up to about 0.04 at.% and then it is essentially constant for the nominal Ph concentration varying betw een 0.1 and 0.5 at.%. The solute rhodium atom concentration is 3 times larger at the melting point than at 750 K.