Acoustic emission and self-organized criticality associated with fracture processes during hydrogen precipitation in Nb

Acoustic emission activity was detected in niobium during hydrogen precipitation from solid solution. The observed emission is attributed to the nucleation and propagation of microcracks generated by the misfitting growing precipitate particles. Analysis of the acoustic signals reveals that the distribution of their amplitudes follows the Gutenberg--Ritcher law of earthquakes N(A? >A) ? A-c, c = 0.9. The observed power law indicates that during the fracture processes caused by the precipitation, the Nb?H system goes into a self-organized critical state, similar to what occurs in the earth's crust during earthquakes.