Dislocation loops in proton irradiated Zr and Zry-4 · neutron irradiated zirconium". In: Journal...
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Damage v. irradiation depth Dislocation loops in proton irradiated Zr and Zry-4 Hattie X.D. Xu, Tamas Ungar, Philipp Frankel, Michael Preuss [email protected] Materials Performance Centre, University of Manchester Sponsors References [1] Jostsons, A., P. M. Kelly, and R. G. Blake (1977). “The nature of dislocation loops in neutron irradiated zirconium". In: Journal of Nuclear Materials 66.3, pp. 236--256. [2] Ribarik, G., & Ungar, T. (2010). Characterization of the microstructure in random and textured polycrystals and single crystals by diffraction line profile analysis. Materials Science and Engineering A, 112-121. Introduction In service, neutron irradiation knocks atoms out of lattice, creating vacancies and self-interstitial atoms (SIA). Point defects may annihilate or form clusters, which then collapse into dislocation loops. Macroscopically, Zr crystals elongates in <a> and shrinks in <c> — aka. irradiation-induced growth (IIG). We proton irradiate a Zr and Zry-4 to mechanistically study these effects. Particle hits primary knock-on atom (PKA) Collision cascade, point defects form Dislocation loop formation Key findings 1. Point defect mobility higher in pure Zr than in Zircaloy-4. After same irradiation, pure Zr has fewer, larger dislocation loops than Zircaloy-4. 2. Using bright field STEM, we can characterize the nature of <a>- loops larger than ~20 μm. 3. At higher dose (4 dpa) where <c>- loops are observed, <a>-loops align along <10-10> family of directions. Is <a>-loop alignment related to <c>-loop formation? 4. <a>-loops in alignment are of similar sizes, and of the same nature (identical Burgers vector)! 5. At low proton dose (~0.15dpa at 60% proton penetration depth), depth-dependence of dislocation density agrees with SRIM dose profile! 6. XRD satellite peaks may contain loop nature information, and may be orientation-dependent. 7. At high dose (~4dpa at 60% penetration depth), damage profile does not show a Bragg peak as predicted by SRIM. 8. In general, SRIM (quick Kinchin- Pease, E d(Zr) =40eV, amorphous) slightly overestimates proton penetration depth in Zr. PWR cladding assembly <a>-loops, alignment & nature Zr 350 ° C 4dpa ρ (CMWP) = 7 × 10 14 /m 2 01-10 Zr at 4 dpa, <c>-loops appear. <a>-loops align along <10-10>. Aligned loops: same size & nature (here: interstitial) (S)XRD line profile analysis = ∗ ∗ ∗ + • Broadening strain; loop density ρ • Tail shape dipole factor; loop size Bragg peaks • Lower d-spacing interstitial • Higher d-spacing vacancy • hkl dependent Asymmetric satellites Zr 450 ° C 2dpa Z ry - 4 450 ° C 2dpa ρ (CMWP) = 2 × 10 13 /m 2 ρ (CMWP) = 4 × 10 13 /m 2 Pure Zr: fewer, larger loops compared to Zircaloy-4 450C irradiation: huge loops; concurrent annealing During long irradiations, Bragg peak damage disappears due to diffusion of defects over time! Synchrotron X-ray diffraction d ; high energy; focused beam; transmission; depth sequence. 10.3 00.4 00.4 10.3 d larger, vacancy d smaller, interstitial Acknowledgements a Dalton Cumbrian Facility, The University of Manchester, Cumbria, UK b Elettra Sinchrotrone Trieste, Trieste, Italy c Diamond Light Source, Oxfordshire, UK d PETRA III, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany We integrate diffraction b,c patterns into line profiles, then do Convolutional Multiple Whole Profile (CMWP) [2] analysis. Peak broadening: depth- dependent in low dose only Zr 450°C 2dpa Zr 350°C 4dpa smaller Vacancy larger larger Interstitial smaller Inside-outside contrast [1]
Transcript of Dislocation loops in proton irradiated Zr and Zry-4 · neutron irradiated zirconium". In: Journal...
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Damage v. irradiation depth
Dislocation loops in proton irradiated Zr and Zry-4 Hattie X.D. Xu, Tamas Ungar, Philipp Frankel, Michael Preuss
[email protected] Materials Performance Centre, University of Manchester
Sponsors References [1] Jostsons, A., P. M. Kelly, and R. G. Blake (1977). “The nature of dislocation loops in
neutron irradiated zirconium". In: Journal of Nuclear Materials 66.3, pp. 236--256.
[2] Ribarik, G., & Ungar, T. (2010). Characterization of the microstructure in random and
textured polycrystals and single crystals by diffraction line profile analysis. Materials
Science and Engineering A, 112-121.
Introduction In service, neutron irradiation knocks atoms out of lattice, creating vacancies and self-interstitial atoms (SIA). Point defects may annihilate or form clusters, which then collapse into dislocation loops. Macroscopically, Zr crystals elongates in <a> and shrinks in <c> — aka. irradiation-induced growth (IIG). We proton irradiatea Zr and Zry-4 to mechanistically study these effects.
Particle hits primary knock-on atom (PKA)
Collision cascade, point defects form Dislocation loop formation
Key findings 1. Point defect mobility higher in
pure Zr than in Zircaloy-4. After same irradiation, pure Zr has fewer, larger dislocation loops than Zircaloy-4.
2. Using bright field STEM, we can characterize the nature of <a>-loops larger than ~20 μm.
3. At higher dose (4 dpa) where <c>-loops are observed, <a>-loops align along <10-10> family of directions. Is <a>-loop alignment related to <c>-loop formation?
4. <a>-loops in alignment are of similar sizes, and of the same nature (identical Burgers vector)!
5. At low proton dose (~0.15dpa at 60% proton penetration depth), depth-dependence of dislocation density agrees with SRIM dose profile!
6. XRD satellite peaks may contain loop nature information, and may be orientation-dependent.
7. At high dose (~4dpa at 60% penetration depth), damage profile does not show a Bragg peak as predicted by SRIM.
8. In general, SRIM (quick Kinchin-Pease, Ed(Zr)=40eV, amorphous) slightly overestimates proton penetration depth in Zr.
PWR cladding assembly
<a>-loops, alignment & nature
Zr 350°C 4dpa
ρ(CMWP)=7×1014/m2
01-1
0
Zr at 4 dpa, <c>-loops appear. <a>-loops align along <10-10>. Aligned loops: same size & nature (here: interstitial)
(S)XRD line profile analysis 𝐼𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 = 𝑰𝑺𝒕𝒓𝒂𝒊𝒏 ∗ 𝑰𝑺𝒊𝒛𝒆 ∗ 𝑰𝑷𝒍𝒂𝒏𝒂𝒓𝑫𝒆𝒇𝒆𝒄𝒕𝒔 ∗ 𝐼𝐼𝑛𝑠𝑡𝑟𝑢𝑚𝑒𝑛𝑡 + 𝐵𝐺
• Broadening strain; loop density ρ
• Tail shape dipole factor; loop size
Bragg peaks
• Lower d-spacing interstitial
• Higher d-spacing vacancy
• hkl dependent
Asymmetric satellites
Zr 450°C 2dpa Zry-4 450°C 2dpa
ρ(CMWP)=2×1013/m2 ρ(CMWP)=4×1013/m2
Pure Zr: fewer, larger loops compared to Zircaloy-4 450C irradiation: huge loops; concurrent annealing
During long irradiations, Bragg peak damage disappears due to diffusion of defects over time!
Synchrotron X-ray diffractiond; high energy; focused beam; transmission; depth sequence.
10.3
00.4
00.4 10.3
d larger,
vacancy
d smaller,
interstitial
Acknowledgements a Dalton Cumbrian Facility, The University of Manchester, Cumbria, UK b Elettra Sinchrotrone Trieste, Trieste, Italy c Diamond Light Source, Oxfordshire, UK d PETRA III, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
We integrate diffractionb,c patterns into line profiles, then do Convolutional Multiple Whole Profile (CMWP)[2] analysis.
Peak broadening: depth-dependent in low dose only
Zr 450°C 2dpa
Zr 350°C 4dpa
smaller Vacancy larger
larger Interstitial smaller
Inside-outside contrast[1]
