Structural Evaluation of Ti-Cr-Si-B Powders Produced by High-Energy Ball Milling and Sintering

Multicomponent Ti6Si2B-based alloys are potentially attractive for structural applications due to the low Ti6Si2B crystallographic anisotropy, and their oxidation resistance are higher than the Ti5Si3-based alloys. There is a limited amount of information on effect of alloying on stability of Ti6Si2B. The present work reports on the structural evaluation during ball milling and subsequent sintering of Ti-2Cr-22Si-11B and Ti-7Cr-22Si-11B (at-%) powders. The milling process was carried out in a planetary Fritsch P-5 ball mill under Ar atmosphere using hardened steel balls (19 mm diameter), stainless steel vials (225 mL), rotary speed of 300 rpm, and a ball-to-powder weight ratio of 10:1. Samples were collected after different milling times: 20, 60, 180, 300, 420 and 600 min. Addicional wet milling (isopropyl alcohol) for 20 more minutes was adopted to increase the yield powder into the vials. Following, the powders milled for 620 min were uniaxially compacted (20 MPa) in order to obtain cilinder green bodies with 10 mm diameter and subsequently sintered under vacuum at 1100°C for 240 min. The milled powders were characterized by X-ray diffraction, and scanning electron microscopy. The chromium addition have contributed to form a large amount of Ti6Si2B in the mechanically alloyed and sintered Ti-2Cr-22Si-11B and Ti-7Cr-22Si-11B alloys.