Control of Formation, Dispersion and Morphology of TiB2 Particles in Al-TiB2 Metal Matrix In-Situ Composite through Optimization of Melt Condition

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Khalatbari, Fatemeh | 2013

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 45123 (07)
University: Sharif University of Technology
Department: Materials Science and Engineering
Advisor(s): Varahram, Naser; Davami, Parviz
Abstract:
A study has been carried out on the formation of TiB2 particles in an aluminum based in-situ metal matrix composite by mixing master alloys containing Ti and B i.e., Al-10Ti and Al-8B with a Ti:B weight ratio of 5:2. It was shown that the microstructure of the composite was greatly affected by the controlling factors of the in-situ reaction like temperature, reaction time and stirring of the melt. An increasing reaction time leads to the dissolusion of the primary phases (AlB2 and Al3Ti) and the increase in TiB2 volume fraction. Optical microscope and SEM images were used to study these changes and XRD analysis was applied to confirm these observations. The act of melt stirring in short intervals (15 minute) was found to have a great effect on the distribution of the existing phases; TiB2 agglomeration rings and particle clustering behavior disappeared except for the reaction time exceeding 3 hours. The increase in particle size with a prolonged reaction time was not observed but that was certainly a more uniform size distribution in the stirred melt; fine TiB2 particles with a size of less than 2μm were distributed through out the aluminum matrix
Keywords:
Distribution ; Metal Matrix Composite (MMC) ; In-Situ Reaction ; Cluster ; TiB2 Particles

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