Refractory alloys with silicides and borides have been used in high temperature applications because their elevated melting point, good oxidation resistance and high strength-to-weight ratio. The present study approaches the preparation of Ti-7.5Si-22.5B (at.-%) alloys through high-energy ball milling and sintering. The powders and compacts obtained in these processes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), density measurements, chemical analyses and Vickers hardness. It was verified that silicon and boron powders are dissolved in the titanium during milling with an iron contamination up to 6.0 at.-%. Furthermore, the use of short milling times and alcohol during the final stages of milling increases the powder yield. Such increasing was obtained even with a high rotary speed (300 rpm), which generally creates higher temperatures and consequently more sticking. After sintering of the as-milled powders, it was indentified mainly the Ti+Ti6Si2B+TiB+Ti5Si3 phases in the Ti-7.5Si-22.5B sintered alloys, which presented hardness values up to 800 HV. The materials produced by the present work can be employed in coating research as sputtering targets.

Recently, a new ternary phase was discovered in the Ti-Si-B system, located near the Ti6Si2B composition. The present study concerns the preparation of titanium alloys that contain such phase mixed with α-titanium and other intermetallic phases. High-purity powders were initially processed in a planetary ball-mill under argon atmosphere with Ti-18Si-6B and Ti-7.5Si-22.5B at. (%) initial compositions. Variation of parameters such as rotary speed, time, and ball diameters were adopted. The as-milled powders were pressureless sintered and hot pressed. Both the as-milled and sintered materials were characterized by X-ray diffraction, scanning electron microscopy and energy-dispersive spectrometry. Sintered samples have presented equilibrium structures formed mainly by the α-Ti+Ti6Si2B+Ti5Si3+TiB phases. Silicon and boron peaks disappear throughout the milling processes, as observed in the powder diffraction data. Furthermore, an iron contamination of up to 10 at. (%) is measured by X-ray spectroscopy analysis on some regions of the sintered samples. Density, hardness and tribological results for these two compositions are also presented here.