Solid-State Alloying and Amorphization of Immiscible Elements

9613865 Ma本研究涉及远离平衡的金属合金，即非晶态合金和过饱和纳米晶固溶体。重点是在具有大的正混合热的二元系统中使用固态处理技术形成亚稳态相。一个系统的实验方法应该能更清楚地理解不相容体系中亚稳态相的形成及其转变。探索的科学领域包括：在一些机械合金化的二元不混溶系统中观察到的非晶化机制；在这类系统中合金化程度的限制；这些亚稳态相的稳定程度；短程聚集程度；以及通过不同的固态技术制备的不相容合金的热力学行为的异同。采用的测量技术包括量热法、透射电子显微镜、热力学建模和扩展X射线吸收精细结构分析。要了解不相容合金体系的合成、结构和稳定性，需要发展不相容合金体系的热力学和动力学现象的基本原理。***

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. ***