کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1795483 | 1023723 | 2007 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Halo formation in directional solidification of Ni–Ni3Nb hypereutectic alloy Halo formation in directional solidification of Ni–Ni3Nb hypereutectic alloy](/preview/png/1795483.png)
The pulling velocities under directional solidification were calculated and compared with experimental results for various growth temperatures of different phases in Ni–24.19% Nb hypereutectic alloy. When the pulling velocity is 1 μm/s, coupled growth eutectic was obtained in experiment, in agreement with the calculated result of 1.1 μm/s at the temperature gradient of 160 K/cm in liquid. As the pulling velocity increases to 2 μm/s, primary β-Ni3Nb plate dendrites and coupled growth eutectic microstructure appeared. At the pulling velocity of 10 μm/s, halo α-Ni dendrites formed from the Ni-rich solute neighbor to primary β-Ni3Nb phase, and followed by the growth of coupled eutectic. The critical pulling velocity required to form the halo α-Ni dendrites was calculated as 16 μm/s by Nave et al.'s model [Acta Materialia, 50(2002) pp. 2837–2849]. This matches well with the experiment result of 10 μm/s. The calculation also shows that α-Ni haloes will not appear at the composition below 23.35% Nb in the directionally solidified Ni–Ni3Nb hypereutectic alloys.
Journal: Journal of Crystal Growth - Volume 299, Issue 1, 1 February 2007, Pages 178–183