Hot-workability Studies of TiAl-based Intermetallic Composites with In Situ Synthesized Silicide and Carbide Reinforcements

Description

TiAl-based intermetallic alloys possess attractive high temperature properties with low densities, and are candidate materials for applications in gas turbines, jet engines, and automobiles. However, their ductility at low temperatures is limited due to very large grain size and lamellar microstructure developed in cast alloys. These problems are being addressed by using powder metallurgy techniques including the investigators’ novel approach to improve their ductility as well as strength. In this technique, Si- and C-containing TiAl-based composites are synthesized in situ using mechanical alloying and reactive sintering during hot isostatic pressing. Adequate workability of sintered billets can be achieved by hot forging in a selective temperature range and strain rate to cause dynamic recrystallization, which mitigates the undesirable effects of prior particle boundary defects. Designing this critical step requires the hot deformation behaviour and the microstructural evolution of the sintered billet to be characterized.This project aims to develop the essential scientific understanding of the hot working behaviour of TiAl intermetallic composites using hot compression testing and well-established modelling techniques such as kinetic analysis and processing maps that directly help in the design of optimum forging processes for component manufacture of this important high temperature material.