Advanced Characterization of Hydrides in Zirconium Alloys

Dislocation modelling of the plastic relaxation and thermal ratchetting induced by zirconium hydride precipitation

“…There are no horizontal slip planes aligned with the [11 20], which is also parallel to the long axis of the hydride. With this, we are considering that the hydride follows the fcc/hcp orientation relationship that is predominant among those reported in the literature (Hanlon et al, 2018;Bradbrook et al, 1972):…”

“…• the hydride stress field may attract H, thereby affecting both its subsequent growth and the nucleation of neighbouring hydrides; • there is ample evidence that the misfit induces plasticity both inside the hydride (Bai et al, 1992;Wang et al, 2014;Vicente Alvarez et al, 2016) and in the surrounding matrix (Carpenter et al, 1973;Bailey, 1963;Long et al, 2019;Zhao et al, 2008;Hanlon et al, 2018).…”

“…This is referred to, in this context, as thermal ratchetting (Cameron and Duncan, 1977;Eadie et al, 1993;Barrow et al, 2013b;Patel et al, 2017). It is suggested that the dislocations associated with the plastic relaxation are the cause of this ''memory effect'' (Carpenter et al, 1973;Carpenter, 1978;Hanlon et al, 2018).…”

Mechanisms of Hydride Nucleation, Growth, Reorientation, and Embrittlement in Zirconium: A Review

“…In addition to the eutectoid reaction discussed above, δ hydrides can also transform into γ hydrides during tensile testing [ 40 ]. The γ phase is detected at the front of the δ hydride, implying that γ hydride is the precursor of δ hydride [ 41 , 42 ]. After long-term hydrogen charging at high temperatures, ε hydride is formed through the martensitic shear of δ hydrides [ 43 , 44 , 45 , 46 ].…”

“…Local stress is reduced and hydride growth is further increased [ 51 ]. The density of the emitted dislocation is proportional to the square of the hydride length [ 42 , 55 ]. Liu et al, further pointed out the key role of dislocations in the regulation of hydride growth via an in situ experiment [ 56 ].…”