Ag-SnO Alloy composite electrical contact

A heat-treated composite electrical contact consisting of a base portion and a contact portion clad to said base portion,

• said base portion being made from a metal selected from the group consisting of copper, nickel, aluminum and alloys thereof,
• said contact portion consisting essentially of a pre-internally oxidized alloy having metal oxides precipitated in and evenly dispersed throughout the matrix of said alloy as the result of internal oxidation effected prior to the cladding of said contact portion to said base portion, and being composed of 1.5 to 10% weight of tin, 0.5 to 6% by weight of Indium and a trace amount of less than 0.5% by weight of iron family element metals, the balance being silver,
• said contact and base portions being joined by an interfacial alloy layer composed solely of materials from said base and said contact portions, and comprising, respectively, silver from said contact portion, and the matrix metal of said base portion, and consisting essentially of metal oxides from the contact portion wedged into the base portion which prevent abutting surfaces of the base and contact portions from sliding;
• and
• said contact portion, adjacent the side of said interfacial alloy layer remote from said base portion being diffused by the metal of the base portion to a depth beyond said interfacial alloy layer as the result of heat treatment of the contact for a brief period of time, and at a temperature about or higher than the eutectic temperature of silver and the matrix metal of said base portion.