Effect of He ion irradiation on the microstructure of t‧ phase yttria-stabilized zirconia ceramic coatings
Abstract
Yttria-stabilized zirconia (YSZ) films with tetragonal (t‧) phase was prepared on China Low Activation Martensitic steel (CLAMs) substrates by supersonic atmospheric plasma spraying (SAPS) with ZrO2-8wt% Y2O3 nano-powders as feedstock. This study deals with the subject of the structural modifications and phase transformations in t‧ phase YSZ coatings induced by implantation of low-energy (60keV) He ions. It is found that the phase transformation in t‧ phase YSZ coatings during helium ion-irradiation as a function of fluence can be divided into a two-stage process based on the microstructural evolution as follows: (i) In the case of He ions at 0.5×1017cm2 (∼1.5dpa), no obvious volume swelling can be detected, suggesting the irradiation-induced defects is primarily associated with a positive relaxation volume. Therefore, only t‧→t phase transformation was observed for the samples implanted at a fluence of 0.5×1017cm-2. (ii) While increasing the fluence from 0.5×1017cm-2 to 2×1017cm-2, an increase in the defect concentrations can be observed, leading to an exponential growth in volume swelling from 3.2% to 9.7% observed. These high- density extended defects can induce a plastic deformation in the lattice structure, resulting significant lateral compressive stress. Correspondingly, the t‧→t+c phase transformation was detected for the samples implanted at the fluence of 2×1017cm-2. At a fluence of 10×1017cm-2, the formation of the He bubbles, and ellipsoidal cavities can be observed by TEM, inducing the further volume swelling. Meanwhile, the intensity of (4 0 0)c peak increases while fluence increase from 2×1017cm-2 to 10×1017cm-2. Based on the experimental results, a reasonable mechanism for the phase transformation of t‧ phase YSZ samples during He ions irradiation is proposed.
- Publication:
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Nuclear Instruments and Methods in Physics Research B
- Pub Date:
- September 2018
- DOI:
- 10.1016/j.nimb.2018.04.042
- Bibcode:
- 2018NIMPB.431...67L
- Keywords:
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- Yttria-stabilized zirconia;
- Supersonic atmospheric plasma spraying;
- Phase transformation;
- Helium ion-irradiation