In-Situ Synchrotron X-Ray Scattering Study on the Tensile Properties of Neutron Irradiated Ferritic/Martensitic Alloys

摘要

Ferritic/martensitic (F/M) steels has been considered as candidate in-core and out-of-core materials for Generation IV reactors and fusion reactors. The advantages of F/M steels are good mechanical properties, high corrosion resistance and especially high resistance to irradiation compared with austenitic steels. Precipitates such as M_(23)C_6 (M = Cr, Fe, Mo) and MX (M =V/Nb) in F/M steels play an important role in maintaining the integrity of mechanical strength and creep performance. However, the precipitates are unstable under irradiation at high temperatures . In addition, irradiation can cause the formation of radiation-induced phases such as Chi (χ), G-phase and radiation-enhanced phase as a' which leads to increase ductile-to-brittle transition temperature (DBTT) . Understanding particle-dislocation interaction mechanisms is critical for mechanical properties including hardening, embrittlement, and creep resistance. The process of embrittlement or ductile rupture involves many factors such as particle/matrix elastic mismatch, interface decohesion, micro-cracking of particle, and local plasticity of matrix. In order to characterize these factors, it is important to identify the relationship between microstructure and micro-scale mechanical properties. The high-energy X-ray diffraction makes it possible to analyze the load transfer between the matrix and particles or the matrix and radiation damages. By analyzing the diffraction peaks of the matrix, the evolution of edge and screw dislocations can be calculated by using the modified Williamson-Hall (W-H) method. In addition, void or damage evolution by irradiation can be measured by small angle X-ray scattering (SAXS).