Investigation of Formation, Stability, and Structure of Quasicrystal and Related Crystalline Phases

这是针对所选合金中二十面体相的形成和稳定性的实验研究。重点介绍了(1)从精密粉末和单晶X射线衍射研究中确定体心立方的Ti-Cr-Si类化合物的原子结构，(2)扩展了对在Ti-Zr过渡金属合金中发现的相关相的研究；(3)测量体心立方Ti-Cr-Si的低温和高温电阻率，以与已在Al晶体中测量的输运性质进行比较；(4)估算Al-Mn-Si中玻璃-二十面体相和玻璃-α相界面能；(5)扩展Al-Mn原子模型以预测Al-Co-Cu的结构。二十面体相结构和稳定性的研究为金属玻璃和复杂的金属间化合物合金提供了重要的联系。了解这些相的形成是改进金属合金设计所必需的。

This is grant is directed to experimental research on icosahedral phase formation and stability in selected alloys. Emphasized are (1) determination of the atomic structure of the bcc Ti-Cr-Si approximant from precision powder and single crystal X-ray diffraction studies; (2) expansion of the investigation into related phases discovered in the Ti-Zr transition metal alloys; (3) measurement of low and high temperature resistivity in bcc Ti-Cr-Si to compare with the transport properties already measured in Al crystalline approximants; (4) estimation of the glass-to- icosahedral phase and glass-to-alpha phase interfacial energies in Al-Mn-Si; (5) extension of an atomic model for Al-Mn to predict the structure of Al-Co-Cu. %%% Research on icosahedral phase structure and stability provides an important link to metallic glasses and complex intermetallic alloys. Understanding formation of these phases is required for improved metal alloy design.