Creep-resistant silver-based alloy for production of neutron absorption elements includes indium, cadmium and, optionally, hafnium, and their oxides in the form of particles distributed in the alloy

摘要

Silver-based alloy having improved creep resistance and used in the production of neutron absorption elements includes indium, cadmium, optionally hafnium, and oxygen present a dissolved form and in the form of indium, cadmium and hafnium oxides distributed throughout the alloy as particles of size 0.02-2 microns. Preferred Features: The silver-based alloy comprises (in weight %): indium 10-16; cadmium 4-6; oxygen 0.003-1.25 oxygen; optionally hafnium up to 1.5; and silver and unavoidable impurities the remainder. The amount of oxygen present in the alloy is preferably less than 1 weight %, more preferably less than around 0.8 weight %. The oxides in the form of particles mainly comprise indium oxide (In2O3) particles. The preferred size of the particles is 20-300 nm. Independent claims are given for first and second processes for manufacturing a rod from the above-described alloy. The first process for manufacturing a rod from the above-described alloy comprises: (a) producing a silver-indium-cadmium alloy powder by water atomization; (b) compacting the powder at very high pressure to produce a billet; (c) sintering the billet in nitrogen at around 700 degrees C for about an hour; (d) preheating the billet at around 700 degrees C in air or argon for 20-40 minutes; and (e) extruding the billet into the form of a rod at around 700 degrees at a die temperature of around 500 degrees C. The second process for manufacturing a rod from the above-described alloy comprises: (a') producing a silver-indium-cadmium alloy powder by water atomization; (b') controlled oxidation of the powder at high temperature in an oxygen atmosphere, preferably in an autoclave at around 400 degrees C under a pressure of oxygen of 1-10 bars; (c') filling a container with the oxidized powder; (d') closing the container under vacuum; (e') preheating the container for around two hours at around 400 degrees C; (f') extruding the container containing the powder; and (g') removing the container wall to obtain a rod of a silver-indium-cadmium alloy containing oxide particles.