High-resolution transmission electron microscopy investigation of in situ TiC/Al composites

TiC/Al metal matrix composites (MMCs) were produced by in situ reactive hot pressing (RHP) technique. Aluminum, titanium, and graphite powders were used as starting materials. The powders were cold-pressed, rapidly heated to 1200 degrees C, sintered, and then hot pressed. The microstructure and TiC particles were investigated via X-ray diffraction, micro-hardness testing, high resolution scanning electron microscopy-energy dispersive spectrometry, high resolution transmission electron microscopy-energy dispersive spectrometry, and selected area electron diffraction/electron backscattered diffraction-transmission electron microscopy. The properties of the Al matrix and TiC interface were also studied. At 1200 degrees C, only the TiC secondary phase was observed in X-ray diffraction. A hardness value of 99 HV was measured. Scanning electron microscopy and transmission electron microscopy studies revealed submicron and mostly nanosized TiC particles. Round, rod type, and irregularly shaped particles were observed. Transmission electron microscopy examinations showed a clean interface between the in situ TiC reinforcements and aluminum matrix.