Reaction Kinetics Studies on Ti-48Al System to Obtain Activation Energy and Avrami Index by Johnson -Mehl-Avrami aquation

摘要

Gamma titanium aluminides are identified as high performance materials for aerospace sector for applications in the vicinity of 1000 deg C. Reaction synthesis (RS) route based on powder metallurgical technique is being pursued for developing these aluminides due to main advantages of avoiding elemental segregation, fracturing, elemental loss and near net shape processing. In the RS route, heat of reaction between elemental powders is utilised to obtain intermetallic material. Hence, reaction kinetics studies are important for various RS systems. In gamma titanium aluminides, Ti-48at percentAl composition is identified as base composition for further alloy development. In the present paper activation energy and kinetics parameter Avrami Index 'n' are obtained for Johnson - Mehl - Avrami (JMA) equation for the non - stoichiometric reaction relating to this non-stoichiometric composition. The present work is based on the work on non - isothermal crystallization kinetics of metal glasses by J.M. Criado and A. Ortega.