Elastic Property Dependence on Mobile and Trapped Hydrogen in Ni-201

Abstract

Enhanced dislocation processes can accompany decohesion mechanisms dur-ing hydrogen degradation of ductile structural metals . However, hydrogen-deformation interactions and the role of defects in degradation processes re-main poorly understood. In the current study, nanoindentation within specifically oriented grains in as-received, hydrogen-charged, aged , and hydrogen are-charged conditions revealed a "hysteresis " of indentation modu-lus, while the indentation hardness varied minimally. Thermal pre-chargingwith approximately 2000 appm hydrogen decreases the indentation modulus by ~ 20 %, aging leads to a slight recovery, but re-charging drives the modulus back down to values similar to those measured in the hydrogen -charged condition. This "hysteresis" indicates that dissolved interstitial hydrogen isnot solely responsible for mechanical property alterations; hydrogen trapped defects also contributes to elastic property variation.