5. Summary
(1)
The deuterium absorption temperature has a significant effect on cracking. Samples deuterated at 900 °C tend to absorb less deuterium and present few cracks, while samples deuterated at 800 °C and 700 °C tend to absorb more deuterium and present more cracks. These cracks exhibit a net-like shape.
(2)
The deuterium absorption pressure has an obvious effect on cracking. With the increase of deuterium pressure, the deuteride types transform from δ-ZrD1.66 to ε-ZrD1.8, which is believed to be the key factor in the cracking.
(3)
Interrupted cooling has a great influence on cracking. More cracks will appear with the furnace cooling from the higher interrupted temperature.
(4)
The δ-ZrD1.66 phase precipitates from α-Zr phase in strip morphology, while the ε-ZrD1.8 phase precipitates in acicular morphology. The δ-ZrH1.6 phase has an orientation relationship of (0001)α//(001)δ and [2View the MathML sourceView the MathML source 0]α//[001]δ with the α-Zr matrix.