The shape evolution of TiCx prepared by mechanical alloying of Ti-Al-C system after HF treatment

Abstract

This work has investigated the shape evolution of the TiC particles after immersion in the hydrofluoric acid (HF) solutions at different times. The TiC particles were prepared by mechanical alloying of the Ti-Al-C system. The field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) patterns were used to study the phase and morphological evolution of the powders. In addition, the changes in the chemical composition of the solutions were investigated by atomic absorption spectroscopy (AAS). However, the relative intensity, X-ray diffraction full width at half maximum (FWHM) value and the position of the peaks were significantly changed after HF treatment. Results showed that the only detected phase in the XRD patterns of HF-treated samples was TiC. However, there were significant differences between the peaks of the XRD patterns. The results showed that the relative intensity of the (111) planes increased as a function of the immersion time up to 48 h. Moreover, the FWHM values of the peaks revealed that a recrystallization phenomenon occurred for TiC particles after immersion into the HF solutions. The FESEM observations demonstrated that with increasing the time of HF treatment the shape of TiC particles changed from near-spherical to the octahedron and finally cubic morphology.