Enhanced joint strength between TC4 alloy and CFRTP via in-situ constructing sandwich interface with interlocking structure and multi-chemical bonding

Interfacial strength between CFRTP and titanium is still weak and restricts its application in lightweight manufacturing. In this work, a new concept by in-situ constructing a sandwich interface with an interlocking structure and multi-chemical bonding to enhance interfacial strength was proposed. A novel method by designing and presetting interlayers with intersect-curved structures and dissimilar compositions was put forward to realize this in-situ construction. On the one hand, through presetting interlayer with designed intersect-curved structures, surface of CFRTP is changed from continued-heating to alternated-heating, which increases the maximum heat-input tolerance of CFRTP and prolongs cooling time. These contribute to deeper pinning depths with fully-filled resin into intervals, which greatly improve the interlocking strength at interface. On the other hand, by choosing an interlayer with a constituent chemically active with both CFRTP and base metal, the interfacial reaction is further enhanced, resulting in multi-chemical bonding including Fe-Ti and Fe-O at interface. This sandwich interface contributes to high strength of 45 MPa, which was 55% higher than non-interlayer samples in high heat input and four-folds higher than non-interlayer samples in low heat input. Compared with existing pre-treatment methods, this method was quite worth being recommended due to outstanding performance and low cost.