Theoretical and Experimental Study on the Formation Mechanisms of TiAl: Using the Method of Molecular Dynamics Simulation and SPS Method

The present study aimed to investigate the mechanism of TiAl formation through molecular dynamics simulation (MDS) and spark plasma sintering (SPS) methods. The results of the MDS method suggested that TiAl3 is the first intermetallic compound formed by the diffusion of Ti(s) and Al(l) atoms into their interface at 1340 K, followed by the formation of the Ti3Al compound on the interface of Ti/TiAl3. Afterward, by the diffusion of Al(l) atoms into the layers, Ti2Al5 and then TiAl2 compounds were formed on the interfaces of Ti3Al/TiAl3 and Ti3Al/Ti2Al5, respectively. Finally, the TiAl compound formed on TiAl2/Ti3Al interface by a similar procedure. Indeed, the formation mechanisms of TiAl were controlled by the diffusion mechanism to the different interfaces formed during the process. Moreover, the SPS process was employed to validate the MDS results through Rietveld's analysis of the XRD patterns and microscopic structure investigations by SEM and FESEM, in addition to EDX spectroscopy, for the samples at various times. Comparing the results obtained by the MDS and SPS methods revealed that, despite the limitations of the MDS method, this atomic scale method can effectively predict the formation mechanisms of the intermetallic compounds.