Minoru Nobuki1, Junji Takahashi1 and Tokuzou Tsujimoto1
1National Research Institute for Metals, Tokyo
In order to study the hot workability of TiAl, compressive tests have been conducted at the temperatures of 1200~1500 K and the strain rates of 10-4~10-1 s-1 for vacuum arc melted materials weighing about 60 kg and plasma beam melted material weighing about 10 kg.
Maps of the flow stress and deformability for TiAl as the functions of temperature and strain rate are obtained.
The range of good hot-workability for the TiAl single phase material is between 320 and 350 MPa in flow stress. The condition for good workability becomes severer with increasing volume of Ti3Al in the TiAl+Ti3 Al two-phase material; that is, a higher temperature and a lower strain rate are needed in comparison with the TiAl single phase material.
The poor workability in the two-phase material with the lamellar structure of TiAl and Ti3Al results from the facts that deformation is liable to occur heterogeneously and the twinning deformation is active up to higher temperatures.
TiAl intermetallic, compound, hot working, flow stress, deformability, isothermal farging
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