Eutectic formation during directional solidification: Effect of the withdrawal rate

In this paper, the Nb–22Ti–14Si–4Cr–2Al–2Hf alloy was processed by liquid-metal-cooled directional solidification with the withdrawal rates of 20, 100, 300, 400 and 800 μm/s. The morphology and volume fraction of eutectic cells (NbSS+Nb5Si3) varied with the withdrawal rate and the impact was remarkable. The formation rule of eutectic was also deduced. When the withdrawal rate ranged from 300 to 400 μm/s, this type of eutectic cells (NbSS+Nb5Si3) was obtained, in which NbSS and Nb5Si3 were distributed evenly and well aligned with the growth direction.

► Directional solidification at wide range of withdrawal rate (20–800 μm/s).
► Investigating the formation rules of eutectic and the effect of withdrawal rate.
► Exploring the appropriate process conditions for Nb–22Ti–14Si–4Cr–2Al–2Hf alloy.
► Expected microstructure was obtained at the withdrawal rates of 300–400 μm/s.