A Study on the Formation of Intermetallics During the Heat Treatment of Explosively Welded Al-Ti Multilayers

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2014-04, Vol.45 (4), p.1823-1832
• Main Authors: Foadian, Farzad, Soltanieh, Mansour, Adeli, Mandana, Etminanbakhsh, Majid
• Format: Article
• Language: English
• Subjects: Aluminum base alloys; Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Diffusion; Exact sciences and technology; Formations; Heat treating; Intermetallic compounds; Intermetallic phases; Intermetallics; Joining, thermal cutting: metallurgical aspects; Laminates; Materials Science; Metallic Materials; Metallurgy; Metals. Metallurgy; Nanotechnology; Structural Materials; Surfaces and Interfaces; Thin Films; Titanium aluminides; Titanium aluminum alloys; Titanium base alloys; Welding
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-013-2144-6

Metallic–intermetallic laminate composites are promising materials for many applications, namely, in the aerospace industry. Ti/TiAl 3 laminates are one of the interesting laminate composites, which are mostly used in aerospace applications. In this work, commercially pure aluminum and titanium sheets were explosively joined. The multilayer samples were annealed between 1 and 260 hours at 903 K (630 °C) in ambient atmosphere, and the formation and growth of the intermetallic compound at the Ti/Al interface were monitored. Microstructural investigations were carried out using optical and scanning electron microscopes equipped with energy-dispersive spectroscopy and the X-ray diffraction technique. The microhardness profile of the layers was also determined. The thickness and type of Al-Ti intermetallics were determined. It was found that the only intermetallic phase observed in the interfaces was TiAl 3 . It was also shown that two mechanisms for TiAl 3 growth exist: reaction and diffusion controlled. The growth exponent was equal to 0.94 for the reaction-controlled mechanism (first step) and 0.31 for the diffusion-controlled mechanism (second step). These values were in good agreement with theoretical values (1 and 0.5 for the first and second steps, respectively). Based on the results of this research, a kinetic model for the formation and growth of TiAl 3 intermetallic phase was proposed.