Acoustic emissions during hydride formation

When a metal or alloy forms a hydride, the phase change is usually accompanied by the release of acoustic energy. The density changes that accompany hydride formation may also produce cracking and flaking. The acoustic emission accompanying these processes has been used to follow hydriding reactions and the technique has proven to be sensitive in the detection of boundaries on phase diagrams. Acoustic emission has been used to survey the hydriding properties of a number of alloys and metals (FeTi, LaNi5, UAl2, and Nb). This technique has proven useful as a method for monitoring particle breakup and for identifying laboratory procedures necessary to activate the hydride