Quantification of Hierarchal Microstructures of Metallic Materials and the Prediction of the strength by Homogenization Method

材料的微观组织变化是多相相互作用的结果，在金属材料中，利用微观组织的不均匀性来设计材料的性能。本研究的目的是定量地阐明不均匀组织的组织演变，并估计耐热金属材料的性能变化，这是一个复杂的层次多相。为了实现这些目的，我们采用了“系统自由能”的概念，并利用“系统自由能”的概念对材料的微观结构变化程度进行了量化。采用相场法模拟了镍基高温合金中筏状组织从形成到崩溃的一系列微观组织演化过程，并将其结果用于理解蠕变强度 ...更多信息 的合金。结果表明，随着蠕变时间的增加，蠕变应变的对称性由立方对称变为四次方对称。结果表明，垂直于γ ′相[001]方向形成的筏状结构改变了结构的稳定方向，变成了波浪形。筏状组织稳定性的变化与高温合金的蠕变强度密切相关，即当筏状组织稳定时，蠕变强度保持较高。此外，有人发现，蠕变应变是能够推断出的筏状结构的形状。还得到了铁素体耐热钢蠕变强度与分级组织的关系，马氏体板条、块状和束状相的稳定性与其长期蠕变强度直接相关，通过一系列三元系扩散实验获得的c交叉互扩散系数，阐明了合金元素对分级组织稳定性的影响。在三元体系中，通过扩散实验得到了四个互扩散系数，并将基体金属中合金元素之间的相互作用作为两个交叉互扩散系数的符号。少

Microstructural changes of materials axe emerged as a result of interactions of multi-Sixes in it. In metallic materials, the properties have been designed by using the inhomogeneousity of the microstructure The purposes of this study are to elucidate quantitatively the microstructural evolution of the inhomogeneous microstructure and to estimate the change of properties of heat resistant metallic materials, which show a complex hierarchy multi-phase. In order to perform these purposes, we employed the concept of “System Free Energy" and quantified the degree of the microstructural change using the concept This quantification made it possible to obtain the relationship between the microstructural al evolution and the strength change of the materials For example, a series of microstructural evolution from the formation to collapse the rafted structure in nickel-based superalloys was simulated by the Phase-field method, and the results were considered for understanding the creep strength … More of the alloys. It was found that the symmetry of the eigen strain changed from cubic to tetragonal as a result of the increase of the creep strain with increasing creep time. As a result the rafted structure formed perpendicular to [001] direction of the gamma-prime phase became wavy shape by changing the stable direction of the structure. The change in the stability of the rafted structure was strongly related to the creep strength of the superalloys, i.e. the creep strength was kept high when the rafted structure was stable. Furthermore, it was found that the creep strain was able to deduce from the shape of the rafted structures. The relationship between the creep strength and the hierarchal microstructure of ferritic heat resistant steels was also obtained, i.e., the stability of the lath, block and packet of the martensite phase was directly related to the long-term creep strength of them.The effects of alloying elements on the stability of the hierarchal microstructures were elucidated by the c cross-interdiffusion coefficients obtained from a series of diffusion experiments using ternary systems. In ternary systems, four interdiffusion coefficients were obtained by the diffusion experiments, and the interactions between the alloying elements in the host metal were emerged as the sign of two cross interdiffusion coefficients. Less