Microstructure and Mechanical Properties of n-Irradiated Fe-Cr Model Alloys
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0981-JJ07-06
Microstructure and Mechanical Properties of n-Irradiated Fe-Cr Model Alloys Milena Matijasevic and Abderrahim Al Mazouzi Reactor Materials Research, SCK.CEN, LHMA, Boeretang 200, Mol, 2400, Belgium
ABSTRACT High chromium ( 9-12 wt %) ferritic/martensitic steels are candidate structural materials for future fusion reactors and other advanced systems such as accelerator driven systems ADS). Their use for these applications requires a careful assessment of their mechanical stability under high energy neutron irradiation and in aggressive environments. In particular, the Cr concentration has been shown to be a key parameter to be optimized in order to guarantee the best corrosion and swelling resistance, together with the least embrittlement. In this work, the characterization of the neutron irradiated Fe-Cr model alloys with different Cr % with respect to microstructure and mechanical tests will be presented. The behavior of Fe-Cr alloys have been studied using tensile tests at different temperature range ( from -160°C to 300°C). Irradiation-induced microstructure changes have been studied by TEM for two different irradiation doses at 300°. The density and the size distribution of the defects induced have been determined. The tensile test results indicate that Cr content affects the hardening behavior of FeCr binary alloys. Hardening mechanisms are discussed in terms of Orowan type of approach by correlating TEM data to the measured irradiation hardening. INTRODUCTION High-Chromium ferritic-martensitic (FM) steels are candidate structural materials for high temperature applications in fusion reactors as in other advanced nuclear systems such as accelerator driven ones (ADS), due to their inherently good dimensional stability under intense irradiation conditions. Their Creep strength is adequate up to 823 –873 K, and they have been used at these temperature in power-generation and chemical and petrochemical industries. A major issue of this material is the radiation induced hardening/embrittlement and degradation of fracture properties [1]. The technology for production and fabrication of 9-12% Cr steel exists. For the reduced activation ones, their chemical composition is suitable for commercial production only with a large industrial investment [2]. This composition has been obtained following important experimental qualification programs that were carried out worldwide over the last three to four decades [3]. Thus, Cr concentration has been shown to be a key parameter which needs to be optimized in order to guarantee the best corrosion and swelling resistance, together with the minimum embrittlement [4]. However, until recently, there were no accompanying theoretical efforts to rationalize this selection. Indeed, only very recently that Malerba and co-workers have demonstrated that Cr plays an important role in the mobility of interstitial produced clusters which would explain the low swelling rate of such steels [5]. The general objective of this work is to investigate the effect of the ferritic/marte
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