Growth of intermetallic layer in multi-laminated Ti/Al diffusion couples

✍ Scribed by L. Xu; Y.Y. Cui; Y.L. Hao; R. Yang

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 972 KB
• Volume: 435-436
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2006.07.077

✦ Synopsis

Solid-state reactive diffusion between Ti and Al was investigated in the temperature range of 520-650 • C by employing multi-laminated Ti/Al diffusion couples. In samples annealed up to 150 h intermetallic TiAl 3 is the only phase observed in the diffusion zone and the preferential formation of this compound in Ti/Al diffusion couples was predicted using an effective heat of formation model. The present work indicated that both Ti and Al diffused into each other and the growth of the TiAl 3 layers occurred mainly towards the Al side. The TiAl 3 growth changes from parabolic to linear kinetics between 575 and 600 • C, characterized by activation energy of 33.2 and 295.8 kJ mol -1 , respectively. It is suggested that the low-temperature kinetics is dominated by the diffusion of Ti atoms along the grain boundaries of the TiAl 3 layers, while the reaction at the TiAl 3 /Al interfaces in the high-temperature regime is limited by the diffusion of Ti atoms in the Al foils as a result of increased solubility of Ti in Al with increasing temperature.