Microstructure and mechanical properties of hot-pressed Ti–Co–Si compounds reinforced by intermetallic phases

Abstract

Monolithic TiCo and Ti5Si3 phases and Co(ss)/Ti5Si3–Ti3Co2Si nanocomposite were fabricated via mechanical alloying followed by hot-pressing (HP). The XRD patterns of bulk samples showed a general decrease in peak widths after hot-pressing owing to an increase in crystal size caused by exposure to high temperature during the HP process. Nevertheless, the nano-crystallinity of the structure was retained after HP and no new phase was formed. As a dominant fracture mode, this material exhibited an intergranular fracture feature with low dimpled ruptures. Dry-sliding wear behavior was evaluated at room and high temperatures. The mean coefficient of friction and wear rate gradually decreased with increasing temperature due to the presence of discontinuous thin tribo-oxide and tribo-nitride layers on the worn surface. The wear rate obtained in this work was ~10 times lower than that previously reported for Ti compounds.