An Investigation on the Mechanism of TiC+Al₂O₃ Formation in the Combustion Synthesis of the Mechanically Activated TiO₂-Al-C System

Abstract:

A mechanism for the combustion synthesis of TiC+Al2O3 was proposed in a mechanically activated TiO2-Al-C system. As-milled powder mixture was analyzed using XRD and TEM techniques where no chemical reaction and/or inter-particle diffusion were identified. The results obtained from DTA tests on unmilled powder revealed that the combustion synthesis occurred in a single step at 962 °C while the synthesis of mechanically activated powder mixture occurred in three different stages. The XRD analysis on the synthesized samples of 8 hour premilled powder at different temperatures showed that the three stages were as follows: First the reaction between Al and TiO2 takes place forming Al3Ti, Ti2O3, and Al2O3 at 700 °C. In the second step, Ti-rich titanium aluminides (AlTi, AlTi2, and AlTi3) and TiO, are formed at 923 °C, and finally the formation of TiC+Al2O3 is completed at 1329 °C.

• Periodical: Defect and Diffusion Forum (Volumes 273-276)
• Pages: 204-209
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.273-276.204
• Online since: February 2008
• Authors: Sayed Hamid Reza Fatemi Nayeri, Jalil Vahdati Khaki, Mohammad Reza Aboutalebi
• Keywords: Al₂O₃, Combustion Synthesis Mechanism, Mechanical Activation (MA), TiC

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