3. Elaboration and transformation

3.1 Ingot production

There are a number of pitfalls when it comes to manufacturing ingots from TiAl-based alloys. Firstly, the difference between the melting points of titanium and aluminum elements means that there is a considerable risk of retaining infusions or vaporizing part of the aluminum. Secondly, the complexity and duration of the various solidification and cooling stages are conducive to the retention of micro- and macrosegregations in the ingot. On the other hand, techniques using a ceramic crucible are not suitable for the production of TiAl, firstly because of the high reactivity of certain elements such as titanium towards the crucible, and secondly because of the addition of certain refractory elements with a high melting point. Consequently, the use of a cooled copper...