The “pinning” effect of in-situ TiB whiskers on the hot deformation behavior and dynamic recrystallization of (10 vol%) TiB/Ti–6Al–4V composites

Abstract

In-situ (10 vol%) TiB/Ti–Al–4V composites were prepared by employing cold isostatic pressing and vacuum sintering. The “pinning” effects of TiB whiskers on the hot deformation behavior and dynamic recrystallization of composites in the temperature range of 1000–1200 °C with strain rates from 0.01 to 10 s−1 were investigated in terms of flow behavior, hot-processing maps, and microstructural evolution. No flow instability region within the specified range was found. The dominant deformation mechanisms of the composites were CDRX and DDRX in the (α+β) and β regions, respectively. Owing to the “pinning” effect, prior-α could generate more grain boundaries by HAGB immigration to move through TiB whiskers. In the β region, owing to the deformation incompatibility and the “pinning” effect, more bulging of grain boundaries induced by TiB whiskers resulted in more nucleation sites for DDRX. On account of the “pinning” effect, TiB whiskers enhanced microstructural refinement by restricting grain growth.

Keywords

• Titanium matrix composites (TMCs)
• Arrhenius constitutive model
• Dynamic recrystallization
• Pinning