FeCrAl合金材料织构对其宏观力学本构关系的影响研究

FeCrAl合金具有优良的高温抗氧化性和耐辐照性能，是事故容错核燃料包壳的重要候选材料. 其在加工过程和热处理过程中易形成α纤维织构（<110>//RD）和γ纤维织构（<111>//ND），会影响材料的宏观力学性能与深加工成形能力. 本研究针对具有不同织构的多晶FeCrAl合金，建立了代表性体元模型, 使用晶体塑性有限元方法，在ABAQUS/Explicit中模拟材料单轴加载下的宏观应力应变曲线，分析不同织构对FeCrAl合金宏观力学本构关系的影响. 计算结果表明，对于具有α织构、γ织构和晶粒无择优取向的材料，在轧向上的应力应变曲线差异较小. γ织构会引起材料强烈的各向异性，在轧面法向上的屈服强度远高于轧向和横向上的屈服强度，这是因为晶粒的<111>方向平行于加载方向，滑移系难以启动. 提高γ纤维织构的比例，将增大轧面法向上的屈服强度. 本研究可以为优化FeCrAl合金材料织构、加工条件和材料力学性能提供参考.

Effects of material texture on the macro-scale mechanical constitutive relations of FeCrAl alloys

Due to good corrosion resistance and oxidation resistance to high temperatures，Iron chromium aluminum (FeCrAl) alloys have been considered as a promising candidate for accident-tolerant fuel (ATF) cladding materials. Some important texture fibers including α (<110>//RD) and γ (<111>//ND) fiber are observed in FeCrAl alloys after rolling or annealing, which could affect the macro-scale mechanical performances and deep processing abilities. In this study, the representative volume elements (RVE) are developed for the polycrystalline materials of FeCrAl alloys with different textures, and the crystal plasticity model is used to describe the anisotropic behavior of single crystal. By applying periodic boundary conditions and using homogenization theory, the crystal plasticity finite element method is adopted with ABAQUS/Explicit to simulate the macro-scale stress/strain curves under the uniaxial loading. The effects of different textures on the macro-scale mechanical constitutive relations are analyzed. The research results indicate that the stress-strain curves along the rolling direction show small deviations for the materials with random orientations, α and γ fiber. However, γ fiber will result in intensive anisotropy. It is found that the yield strength along the normal direction of rolling plane is much larger than those along the rolling direction and transverse direction for the materials with γ fiber. This is induced by the fact that <111> directions of the grains are parallel to the normal direction of rolling plane, which makes the dislocation slip difficult to be activated. An increase of the texture fraction of γ fiber will enhance the yield strength along the normal direction of rolling plane. For the RVE models with a γ fiber texture, the cumulative shear strains of slip systems follow a normal distribution, and the Standard Deviation with loading along the normal direction is smaller than that with loading along the rolling direction. The simulation results could provide a reference for the optimization of material texture, processing conditions and mechanical performances for FeCrAl alloys.