Preparation of Ti+Ti_6Si_2B+Ti_5Si_3 and Ti+Ti_6Si_2B+TiB powders by high-energy ball milling and subsequent heat treatment

摘要

This work reports on the preparation of Ti-7.5Si-22.5B and Ti-18Si-6B (at-%) powders by high-energy ball milling and further heat treatment at 1100°C for 4h. Milled and heat treated powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and microanalysis via SEM/EDS. In both the cases, it was noted that the full width at half maximum (FWHM) values on the Ti peaks was continuously increased until milling for 21h, indicating that supersaturated solid solutions were formed. In the initial milling stage, the Ti lattices were reduced more rapidly in Ti-7.5Si-22.5B powders owing the higher amount of easier diffusible boron. On the other hand, the broadening of Ti peaks was more pronounced in Ti-18Si-6B powders until milling for 11b. due to the in situ precipitation of TiB_2 in Ti-7.5Si-22.5B powders. However, the Ti lattices of Ti-7.5Si-22.5B powders were increased after milling for 21h due to an intense iron contamination. The Ti+Ti_6Si_2B+TiB and Ti-Ti_6Si_2B+Ti_5Si_3 phases were successfully formed hi mechanically alloyed Ti-7.5Si-22.5B and Ti-18Si-6B powders after heat treatment at 1100°C for 4h.