SYMPOSIA PAPER Published: 01 January 2009
STP48162S

Experimental and Modeling Approach of Irradiation Defects Recovery in Zirconium Alloys: Impact of an Applied Stress

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During neutron irradiation, both interstitial and vacancy loops are formed in high concentration in zirconium alloys. Due to this high density of loops, the material is considerably hardened, but the recovery of the radiation damage during a heat treatment leads to a progressive softening of the irradiated material. The recovery of the radiation induced hardening has been investigated using microhardness tests. Transmission electron microscopy (TEM) observations performed on irradiated foils have also shown that the loop density falls while the loop size increases during the thermal annealing. Furthermore, the TEM analysis has revealed that only vacancy loops are present in the material after long term annealing, the interstitial loops having entirely disappeared. A numerical cluster dynamic modeling has also been used in order to reproduce the material recovery for various annealing conditions. The microstructural evolution during mechanical testing with various loading conditions has also been studied. It has been shown that during a creep test with low applied stress (130 MPa) and high temperature (450°C), the microstructure evolution can essentially be explained by the thermal recovery of the loops leading to glide of dislocations as found for an non-irradiated material. At intermediate temperature (400°C), it is shown that for low stress level (130 MPa) the microstructure evolution can also be explained by the thermal recovery of loops, whereas for higher stress (250 MPa), sweeping of loops by gliding dislocations can also occur. In addition, for an applied stress of 130 MPa and a temperature of 400°C, dislocation density is higher in the irradiated material than in the non-irradiated material deformed in the same conditions. It is also shown that secondary slip systems are more activated in the irradiated material than in the non-irradiated material. From this detailed analysis, the mechanical behavior during creep is interpreted in terms of microscopic deformation mechanisms.

Author Information

Ribis, Joë
CEA-DEN/DANS, DMN/SRMA, CEA/Saclay, Gif-sur-Yvette Cedex, France
Onimus, Fabien
CEA-DEN/DANS, DMN/SRMA, CEA/Saclay, Gif-sur-Yvette Cedex, France
Béchade, Jean-Luc
CEA-DEN/DANS, DMN/SRMA, CEA/Saclay, Gif-sur-Yvette Cedex, France
Doriot, Sylvie
CEA-DEN/DANS, DMN/SRMA, CEA/Saclay, Gif-sur-Yvette Cedex, France
Cappelaere, Chantal
CEA-DEN/DANS, DMN/SEMI, CEA/Saclay, Gif-sur-Yvette Cedex, France
Lemaignan, Clément
CEA-DEC, Dir, CEA/Grenoble, Grenoble Cedex, France
Barbu, Alain
CEA-DEN/DANS, DMN/SRMP CEA/Saclay, Gif-sur-Yvette Cedex, France
Rabouille, Olivier
CEA-DEN/DANS, DMN/SEMI, CEA/Saclay, Gif-sur-Yvette Cedex, France
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Details
Developed by Committee: B10
Pages: 674–695
DOI: 10.1520/STP48162S
ISBN-EB: 978-0-8031-8007-9
ISBN-13: 978-0-8031-4514-6