The embrittlement of nickel base alloys containing aluminium and chromium as used for thermocouple materials

Mineral-insulated base-metal thermocouples are subject amongst other things to e.m.f. drift and to grain boundary embrittlement in reactor environments. This paper is primarily concerned with embrittlement failure and considers sulphur attack, carbide formationand oxidation. Selective oxidation is considered to play the major role in embrittlement and a model for selective oxidation is presented with suggestions for remedial action.