Mechanical properties of heat treated gamma TiAl sheet material

The mechanical properties involving tensile strength, creep and fatigue of Ti-46.5at%Al-4at%(Cr,Nb,Ta,B) sheet material have been investigated at room temperature and elevated temperatures. The sheet material was hot rolled from HIPed prealloyed powder compacts. After rolling within the (alpha+gamma)-phase field and a special heat treatment the sheets exhibit a fine-grained near gamma microstructure with a modified cube texture, i.e. the c-axis of the tetragonal unit cell is preferentially aligned in the sheet plane transversely to the rolling direction, which leads to a temperature dependent anisotropy in the mechanical properties. Prior to testing, sheets were subjected to different heat treatments in order to obtain different microstructures, consisting of fine-grained near gamma and coarse-grained fully lamellar microstructure as well as to alter the sheet texture. In order to characterize the microstructures of the tested material transmission electron microscopy investigations were conducted.