Formation of Ultrafine-Grained Ti 3 Al on a Ti48Al2Cr2Nb Intermetallic Alloy Induced by Pulsed Electron Beam Treatment.

The microstructure modifications, phase, and texture formations encountered in a TiAl based Ti48Al2Cr2Nb intermetallic alloy induced by the high current pulsed electron beam (HCPEB) treatment were carefully investigated using scanning electron microscope (SEM), X-ray diffraction (XRD), and electron backscattered diffraction (EBSD) techniques. The initial material contains the majority γ-TiAl phase and the minority α-Ti₃Al phase. After the HCPEB treatment, the initial α-Ti₃Al was dissolved into the melted layer and the very top surface is covered by ultrafine-grained α-Ti₃Al phase having thermal stress induced cracks. EBSD analyses showed that α-Ti₃Al phase on the very top surface has a 001//ND fiber texture and its texture intensity increases with the number of pulses. The superfast thermal stress cycles and the selective evaporation induced by the HCPEB treatment account for the microstructure modifications and formations of ultrafine α-Ti₃Al in the TiAl based intermetallic alloy. [ABSTRACT FROM AUTHOR]