Microstructure Evolution and Mechanical Performances of SiCf Reinforced (Al3Ti + Al3Ni)-Based Metallic–Intermetallic Laminate Composite

Abstract

In present work, a novel SiCf reinforced (Al3Ti + Al3Ni)-based metallic–intermetallic laminate (Ti–(Al3Ti + Al3Ni)/SiCf-MIL) composite without centerline defect was prepared using Ti, Al foils, NiTi wires and SiC fibers by vacuum hot pressing sintering method. Electron backscatter diffraction was employed to characterize the microstructure and phase constituents of Ti–(Al3Ti + Al3Ni)/SiCf-MIL composite during various stages of preparation process. The elimination mechanism of intermetallic centerline was discussed. Besides, quasi-static compressive performance and fracture toughness of the synthesized composite were investigated. The experimental results indicated that as reaction time increasing, the NiTi/Al interfacial reaction occurred prior to the Ti/Al interfacial reaction to form an Al3Ti/Al3Ni zone. Then, the oxides gathered at the front of Ti/Al interfacial reaction layer were dispersed in the intermetallic layer rather than being pushed together to generate the centerline due to the Al3Ti/Al3Ni zone. After reaction, there were no residual NiTi phases and intermetallic layers mainly consisting of Al3Ti and Al3Ni phases were obtained in this composite. In addition, high angle grain boundaries in Al3Ti grains occupied a large proportion, conversely, low angle grain boundaries dominated in Al3Ni grains. Furthermore, stress concentration appears at the interface between layers instead of along the middle plane of intermetallic layer. Moreover, both compressive strength and fracture toughness of the composite are superior in comparison with SiCf reinforced Ti–Al3Ti metallic–intermetallic laminate composite (Ti–Al3Ti/SiCf-MIL) ascribed to the elimination of centerline.