Solid-State Alloying and Amorphization of Immiscible Elements

本研究处理的是远离平衡态的金属合金，即非晶合金和过饱和纳米晶固溶体。重点是亚稳相的形成使用固体处理技术在二元系统的特点是一个大的正混合热。一个系统的实验方法应该导致更清楚地了解亚稳相的形成和他们的转变，在不混相系统。探索的科学领域包括在一些机械合金二元不混相体系中观察到的非晶化机制；在这种体系中合金化程度的限制；这些亚稳相的稳定程度；短程聚类程度；并比较了不同固态工艺制备的非混相合金热力学行为的异同。测量技术包括量热法、透射电子显微镜、热力学模型和扩展的x射线吸收精细结构分析。需要发展非混相合金体系的热力学和动力学现象的基本原理，以了解它们的合成、结构和稳定性。＊＊＊

9613865 Ma This research deals with metallic alloys that are far removed from equilibrium, namely amorphous alloys and supersaturated nanocrystalline solid solutions. The focus is on metastable phase formation using solid-state processing techniques in binary systems characterized by a large positive heat of mixing. A systematic experimental approach should lead to clearer understanding of the formation of metastable phases and their transformations in immiscible systems. Scientific areas explored include the mechanisms responsible for amorphization observed in some mechanically-alloyed binary immiscible systems; limitations to the extent of alloying in such systems; the degree of stability in these metastable phases; the degree of short range clustering; and the similarities and differences in thermodynamic behavior of immiscible alloys prepared through different solid-state techniques. Measurement techniques employed include calorimetry, transmission electron microscopy, thermodynamic modeling, and extended X-ray absorption fine structure analysis. %%% Development of the fundamentals of thermodynamic and kinetic phenomena of immiscible alloy systems is needed to understand their synthesis, structure, and stability. ***