Underlying mechanism of interfacial evolution in laminate IN625/TC4 composites for enhanced mechanical properties

Compared to the homogeneous materials, laminated heterogeneous materials, in contrast to their homogeneous counterparts, display enhanced performance by effectively balancingcombination of strength and plasticity. However, fabricating such materials is challenging, relying on precise interfacial control. In this work, an IN625/ TC4 layered structural material is successfully fabricated by vacuum diffusion bonding process at 900 C-degrees. The IN625/TC4 composite exhibits good combination of strength and ductility due to its layered hetero-structure, is due to mechanical incompatibility between different layers. The diffusion layer's Ni and Ti gradient distribution leads to distinct intermetallic compounds formation, including Ti2Ni, Ni3Ti precipitates, and disordered TiNi entities at the interface. Diffusion-driven interfacial reactions suggest interconnected growth mechanisms of individual intermetallic compounds. Post-bonding annealing treatments reinforced the composite, with annealing temperature affecting tensile strength and ductility. Increased annealing temperature effectively enhanced strength, peaking at 800 C-degrees (857 MPa), but reduced ductility due to additional intermetallic compounds. This study presents a novel structural design for metallic materials to obtain good combination of strength and ductility.