CRACKING OF AMORPHOUS FE40NI38MO4B18 INDUCED BY STATIC CHARGING WITH HYDROGEN

Cracking in amorphous ribbon of Fe40Ni38Mo4B18 without external loadin g could be induced by cathodic charging with hydrogen in 0.1 N H2SO4 5 mg/L NaAsO2. However, before cracking was initiated, the effect of hydrogen on the mechanical properties could be eliminated if hydrogen had been removed. A series of static charging experiments was carried out to study the cracking characteristics in this alloy. The diffusivi ty and concentration of hydrogen were obtained from both permeation an d cathodic charging/thermal evolution experiments. The cause of cracki ng by static charging could be attributed to the build up of an intern al hydrogen pressure around heterogeneous sites. The critical pressure s for crack initiation were calculated based on the diffusivity and co ncentration data.