| Two Al-Fe-V-Si alloys, Al-3Fe-1V-2Si and Al-6Fe-1V-2Si (in wt.%) alloys, have been produced via melt-overflow process (a single roll strip casting process). This process offers relatively fast solidification rate and can produce near net shape products such as thin gauge strips with the fine microstructure free from segregation. This study is aimed at understanding evolution of microstructure during this process. It has been shown that the microstructure of the alloys consists of various phases: bcc phase, icosahedral phase, and hexagonal phase. All the phases are structurally related: i. e. constructed by several icosahedra and octahedra and show similar chemical compositions. The volume fraction and distribution of these phases depend on the solidification rate and the degree of undercooling. The degree of recalescence occurring during solidification also affects the final microstructure, in that there is a transformation of thermally unstable phases to the stable phases during solidification. The solidification sequences in Al-Fe-V-Si alloys are described in terms of the formation of microquasicrystalline phase and the accumulation and transformation of that phase to the metastable and stable intermetallic phases. |
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