Amorphous nickel-phosphorus alloys containing Cr, Mo, W, Al and/or Si were immersed for about 600 hours at 200℃ in liquid sodium which simulated a coolant of the fast breeder reactor by dissolving less than 700 ppm of Zn, Ag, Sb, Mn, Co and Cs. Surfaces of alloys were examined by using X-ray photoelectron spectroscopy and energy dispersive X-ray analysis. Only zinc and silver were trapped by the alloys. The trapped zinc distributed at least to the 3-4μm deep surface region, while silver was found mainly in the depth less than 100 nm. The high concentration of nickel in the alloy was preferable for trapping zinc. As a silver getter, alloying with chromium and/or molybdenum favored but nickel was detrimental. The alloys of high chromium contents were not effective because of formation of a surface film of chromium compounds which prevented direct contact of the alloys with liquid sodium
