Residual stress relief in B 4 C/TC4 joints brazed with Mo foil/AgCuTi–W/Ag–Cu foil/Nb foil composite interlayer

Abstract The investigation of novel, high-strength joining techniques for boron carbide ceramics and titanium alloys was posited to significantly improve the ballistic resistance of advanced ceramic–metal composite armor systems. Previous research pertaining to the brazing of ceramics and metals utilizing Ag–Cu–Ti filler alloys was conducted. Utilizing the Ag–Cu–Ti brazing system as the primary material facilitated the vacuum brazing process between B 4 C ceramics and TC4 titanium alloy. To alleviate the residual thermal stress within the B 4 C/TC4 joint, materials with a low thermal expansion coefficient, specifically tungsten (W), along with refractory metal foils such as Mo foil and Nb foil, were incorporated. A robust connection between B 4 C and TC4 was successfully established by implementing a composite brazing system comprising Mo foil, AgCuTi–W, AgCu foil, and Nb foil. The inclusion of 5 wt.% W content refined the intermediate layer, resulting in a denser organization. Upon the addition of 5 wt.% W, the shear strength attained its peak value of approximately 75 MPa, signifying an 87.5 % surge in comparison to the condition without the additive. Optimizing the mechanical performance of the B 4 C/TC4 joint was possible by prudently integrating suitable quantities of low expansion coefficient materials alongside intermediate brazing layers. Significantly, the combination system comprising nickel-plated B 4 C + Mo foil + AgCuTi-5 wt.% W + AgCu foil + Nb foil + TC4 displayed the utmost shear strength, approximately 101 MPa.