Hydrogen-induced Failure of TiNi Based Alloy with Coarse-grained and Ultrafine-grained Structure

The objective of this work is to investigate the effect of hydrogen-induced fracture of TiNi-based alloy. In this report we performed the first studies comparing inelastic properties and fracture of the specimens of the binary alloy of TiNi wire under the action of hydrogen with coarse-grained (CG) and ultrafine-grained (UFG) microstructure. It is shown that hydrogen embrittlement (HE) occurs irrespective of the grain size in the studied specimens at approximately equal strain values. However, compared to the specimens with CG structure, those with UFG structure accumulate two to three times more hydrogen for the same hydrogenation time. It is found that hydrogen has a much smaller effect on the inelastic properties of specimens with UFG structure as compared to those with CG structure.