Cluster Formulae Of Alloy Phases And Applied In The Metallic Glasses

Traditional crystallography has been unable to describe the complex alloy phases. Cluster being a new description method for the structure and composition is widely used in alloy phases and metallic glasses. Cluster can express the local atomic structure so it can be used to design composition and structure in the functional materials. Thus it can design the metallic glasses quantitatively. Basing on "cluster plus glue atoms" in the quasicrystal and metallic glasses, this method is to be extended and applied to describe macroscopic composition and microcosmic structure. The mainly research content and research results can be summarized as follows:1. Owing to the coordination atoms are not in the same shell in the cluster, so the first problem we should resolve is how to define the cluster accurately. In this paper, Miracle model and radial atomic number density are used to define cluster, and using in Al-Ni-Zr and B-Co-Si alloy phases as examples. The two methods have been compared and the radial atomic number density can be more accurate than Miracle model. The atoms of clusters are not isolated and shared in different models in alloy phases. After sharing, the effective cluster should be used in cluster formulas, expressed by [effective cluster](glue atoms)x.2. There are multiple atomic sequence in the alloy phases, so for each alloy phase there are multiple cluster formulas. The principle cluster has been put forward, which can represent the local atomic structure this alloy phase best. When choosing the principle cluster, the close packed should be considered firstly. Then the product of share and disperse has been considered later.3. The principle clusters can be used for designing metallic glasses. Such as Zr67Ni33which has strong catalytic performance, which can be expressed as [Zr9Ni3](Ni2Zr). Zr63.7Al9.oNi27.3is the best bulk metallic glass, and can be expressed as [Ni3Zr7](Al). Here Zr9Ni3and Ni3Zr7are both principle clusters.4. Further expanding the application of clusters, it is applied to describe covalent compounds. The covalent compounds are not complicated as alloy phase, the centered atoms are all isolated and the atoms on the shell are sharing. Above all, cluster not only can be used in alloy phase and metallic glasses, but also can be applied in covalent compounds, so it is a good method for alloy designing.