Process parameters and formation mechanism of SiCf/Ti6Al4V composites manufactured by a hybrid additive manufacturing method

Abstract

SiC f /Ti6Al4V composites have been widely used in aerospace engineering due to their high specific strength, high specific stiffness, and low density, but traditional preparation methods have high costs and long cycle times. In this paper, SiC f /Ti6Al4V composites were manufactured by a hybrid additive manufacturing method named laser cladding & laminated deposition (LCLD), which combines laser direct energy deposition (DED) and laminated object manufacturing (LOM) techniques. LCLD was performed using an automatic fiber-laying machine. SiC fibers were easily damaged during laser illumination and metal melting. Reducing the heat input decreased fiber damage, but the cladding quality of SiC f /Ti6Al4V deteriorated. The fiber damage under different process parameters was studied. Re-scanning was used to improve the cladding quality of SiC f /Ti6Al4V while preventing damage to the fiber. The results confirm that the hybrid method combining DED and LOM is promising for SiC f /Ti6Al4V composite production. The shielding gas flow rate and defocusing amount did not affect the manufacture of composite materials. Fiber damage was decreased, and unfused defects increased upon increasing the scanning speed and powder feed rate. Upon increasing the laser power, fiber damage was increased, and the number of unfused defects decreased. The optimized parameters were a laser power of 250 W, a scanning speed of 10 mm/s, and a powder feed rate of 2.5 g/min, according to orthogonal experiment results. The cladding quality was significantly improved by the re-scanning process, and intact fibers were obtained. The main components of the interfacial reaction layer were Ti, C, and Si, and the EDS results showed that some C diffused from the fiber to the matrix and interfacial reaction layer.