半固态ZL101合金初生相形貌分形特征的研究

发布时间：2018-07-24 14:17

【摘要】：分形理论自诞生以来,其应用领域涉及到各行各业,在半固态金属组织形貌中的研究也将近十年。然而,由于分形理论本身的不完善,且其概念并不容易理解,多数的研究者也只是在报道分形维数与半固态金属微观组织形貌之间存在着一定的相依性,而其内在的含义和关系程度并没有深究。然而,分形理论与金属微观组织形貌间关系的研究是非常有必要的,因为组织决定性能,明确的组织描述对高效的材料开发而言具有非常重要的意义。本文从分形的概念出发,探寻ZL101合金半固态组织形貌与分形行为之间的契合点,探究半固态组织形成与演变中的分形规律。通过探究“自相似性”的概念,引进“信息熵”对半固态ZL101微观组织形貌进行了探讨,明确了半固态组织演变存在自相似性。用Fourier级数形状谱探究半固态初生相晶粒的形态特征,发现了不同半固态类型的初生相组织形貌间存在的形态学规律,从形态学上得出半固态初生相晶粒的形态演变为有差异性的“相似”演变。另外,对分形维数和金属组织的常规描述指标做比较,明确它们之间的关系程度,及其在描述半固态微观组织形貌中所扮演的角色。即分形维数可以作为固相率和形状因子综合表述,但与晶粒尺寸的相关性很微小。最后,用不同半固态工艺得到了不同物理机制下的半固态组织,并分别建立了分形维数—延伸率经验公式,为以后的研究积累经验。本文的特色之处在于:用统计学方法,从分形维数的基本概念出发,明确了半固态微观组织的演变存在分形特征;明确了计盒维数在描述半固态微观组织形貌时的适用范围;得到了不同半固态工艺下,ZL101微观组织分形维数与延伸率之间的经验公式。
[Abstract]:Fractal theory has been applied in various fields since its birth, and has been studied in semi-solid metal microstructure for nearly ten years. However, due to the imperfection of fractal theory itself and its concept is not easy to understand, most researchers only report that there is a certain dependence between fractal dimension and microstructure and morphology of semi-solid metal. But its intrinsic meaning and the relation degree did not delve deeply. However, it is necessary to study the relationship between fractal theory and metal microstructure, because the structure determines the properties and the clear microstructure description is very important for the development of high efficiency materials. Based on the concept of fractal, this paper explores the interface between the morphology and fractal behavior of semi-solid microstructure of ZL101 alloy, and probes into the fractal law of the formation and evolution of semi-solid microstructure. By exploring the concept of "self-similarity", the microstructure morphology of semi-solid ZL101 is discussed by introducing "information entropy", and it is clear that there is self-similarity in the evolution of semi-solid ZL101. The morphology characteristics of semisolid primary phase were investigated by Fourier series shape spectrum, and the morphology of primary phase with different semi-solid types was found. Morphologically, the morphology of semisolid primary phase grain evolves into a different "similar" evolution. In addition, the fractal dimension is compared with the conventional description index of metal structure, and the relationship between them and their role in describing the morphology of semi-solid microstructure is clarified. The fractal dimension can be expressed as solid fraction and shape factor, but the correlation between fractal dimension and grain size is very small. Finally, semi-solid structures with different physical mechanisms were obtained by different semi-solid processes, and the empirical formulas of fractal dimensionality and elongation were established respectively, which accumulated experience for future research. The characteristics of this paper are as follows: from the basic concept of fractal dimension, the evolution of semi-solid microstructure is clarified by statistical method, and the applicable range of box-counting dimension in describing the morphology of semi-solid microstructure is clarified. The empirical formula between fractal dimension and elongation of ZL101 microstructures in different semisolid processes was obtained.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.21

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