Interfacial and Mechanical Properties of Tial/Ti Laminated Composites by Hot Rolling Bonding

Abstract

TiAl alloy is considered a promising structural material for the aerospace due to its low density, high specific strength, and excellent high temperature performance. However, its limited ductility/toughness at room temperature hinder its widespread engineering applications. To address this issue, this study introduced Ti metal, known for its superior ductility/toughness, into TiAl alloy. TiAl/Ti laminated composites were fabricated by hot pack rolling bonding and the TiAl/Ti interface exhibits strong bonding, effectively preventing the formation of Kirkendall holes on a large scale. This interface region can be categorized into three distinct regions: I, II, and III. The width of zone I is 180 μm and consists of needle-like γ phase within β0 phase matrix. Zone II, with a width of 110 μm, is primarily made up of needle-like α2 phase within β0 phase matrix. Zone III is predominantly composed of α2 phase. The TiAl/Ti interface strength reaches 234 MPa. The tensile strength of TiAl/Ti laminated composites is 421 MPa, with elongation up to 2.72%. This composite exhibit enhanced plasticity compared to TiAl alloy. In addition, a γ/α2/β0 lamellar structure was observed near the interface region, along with nano-YAl2 particles at the interface of α2/γ lamellar. This study analyzes the formation mechanism of the γ/α2/β0 lamellar structure and the TiAl/Ti interface region from the perspective of atomic diffusion. The TiAl/Ti laminated composites with good interfacial bonding by hot pack rolling in this study offering valuable technical support for the engineering application of TiAl composites in the aerospace.

Keywords: Hot rolling bonding, TiAl/Ti laminated composite, Interface, Mechanical properties, Microstructure