Additive manufacturing of a high-strength ZrC-SiC and TC4 gradient structure based on a combination of laser deposition technique and brazing

A ZrC-SiC and TC4 gradient structure (ZTGS) was additively manufactured through the laser deposition technique and brazing process. The research results indicated that SiC-reinforced TC4-based gradient layers could be obtained on the TC4 surface by laser deposition. ZrC-SiC and TC4 coated with gradient layers were brazed using an AgCuTi filler to fabricate the ZTGS. The effects of the gradient structure and brazing parameters on the ZTGS strength were investigated. With an increase in Layer II and Layer III thickness, the ZTGS shear strength increased. The brazing temperature and holding time affected the ZTGS shear strength by controlling the formation and distribution of the Cu4Ti phase in the brazing zone. The strengthening mechanism of the ZTGS was revealed by analyzing the residual stress distribution in the ZTGS. Compressive residual stress was formed in ZrC-SiC adjacent to the TC4 substrate or the deposited gradient layer, which was found to negatively affect the properties of the ZTGS. The increase in gradient layer thickness reduced the maximum residual stress in ZrC-SiC, and the effect of Layer III on the residual stress was more significant than that of Layer II. The calculated residual stress evolution matched the ZTGS property values well, revealing the strengthening mechanism.