journal of materials processing technology 195 ( 2 0 0 8 ) 88–93 journal homepage: www.elsevier.com/locate/jmatprotec Growth of intermetallic layer at roll bonded IF-steel/aluminum interface Vikas Jindal a,* , V.C. Srivastava b a Punjab Engineering College, Chandigarh 160012, India b National Metallurgical Laboratory, Jamshedpur 831007, India article info Article history: Received 10 October 2006 Received in revised form 1 February 2007 Accepted 18 April 2007 Keywords: Roll bonding Steel/aluminum Diffusion Al 5 Fe 2 EHF theory abstract The solid-state reactive diffusion between IF-steel and Al was experimentally studied using IF-steel/Al/IF-steel diffusion couples. The specimens were prepared by a roll bonding tech- nique and then annealed at temperatures 773 K for different time span. At the IF-steel/Al interface in the annealed diffusion couple, wavy layer of Al 5 Fe 2 was observed. The average thickness (T avg ) of Al 5 Fe 2 layer monotonically increases with increasing annealing time (t) according to the equation T avg = k(t) n , where t is time in second. Value of n = 0.5 indicates that interdiffusion through aluminide phase is the rate controlling step. During annealing, IF-steel matrix has undergone recrystallization. Microstructure and hardness measurement of IF-steel shows that recrystallization process completes within 30 min. Effective heat of formation theory has been applied to predict phase formation sequence during annealing of IF-steel/Al/IF-steel diffusion couples. © 2007 Elsevier B.V. All rights reserved. 1. Introduction Intermetallic compounds are material of considerable inter- est because of their high temperature strength, low density and high creep resistance. However, application of inter- metallics has been limited due to their highly brittle behavior at ambient temperature (Stoloff et al., 2000). Whereas, if intermetallics are complemented with ductile metallic layer, together they offer a combination of good strength and tough- ness. Based on this idea, a new class of structural material known as metal-intermetallic laminate (MIL) composites have been developed (Harach and Vecchio, 2001). MILs based on Ti–Al 3 Ti and Ni–Al 3 Ni have attracted considerable attention in the recent past (Harach and Vecchio, 2001; Peng et al., 2005; Luo and Acoff, 2004; Kim et al., 2005). However, steel being one of the important and widely available cheap structural mate- rial, can be a potential candidate for the development of cost ∗ Corresponding author. Tel.: +91 172 2753957; fax: +91 172 2745175. E-mail addresses: vijindal@gmail.com (V. Jindal), vcsrivas@yahoo.com (V.C. Srivastava). effective MIL composite. No significant amount of research in steel–Al based MILs has been reported so far. Generally, synthesis of MILs is accomplished by a sequence of temperature and pressure steps on the alternate stacks of M (Ti, Ni) and Al layer (Harach and Vecchio, 2001; Peng et al., 2005; Luo and Acoff, 2004; Kim et al., 2005). Thickness of Al layer is so chosen that all the aluminum is consumed in the chemical reaction leading to the formation of intermetallic layer. The thickness of the intermetallic layers in the MILs plays an important role in obtaining optimum properties. It is established that the growth of the intermediate phases can be governed by chemical reactions at the interfaces and by interdiffusion of reacting species through different phases. As diffusion phenomenon depends on annealing conditions, i.e. temperature and time, type of aluminide phase and its thickness can be tailored by employing appropriate annealing conditions. 0924-0136/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2007.04.118