MODIFICATIONS NEAR THE SURFACE OWING TO HYDROGEN CYCLING OF THE INTERMETALLICS LANI5 AND LANI5-XALX

The LaNi//5-LaNi//4//. //7//7Al//0//. //2//2 pair of alloys has been selected to stimulate a cycling procedure, as may be encountered in chemical thermal engines working with hydrides. After 1250 cycles the samples have been studied by yield photoelectron spectroscopy and extended X-ray absorption fine structure (EXAFS) technique. The results, recorded at room temperature near the lanthanum and nickel thresholds, are issued from samples which were cycled in a closed system. Little or no degradation is obtained depending on the intermetallic alloy.