TY - JOUR
T1 - Fabrication of titanium single crystal by a floating zone method under extremely low oxygen partial pressure
AU - Hagihara, Koji
AU - Tachibana, Takahiro
AU - Sasaki, Keita
AU - Yoshida, Yoshiyuki
AU - Shirakawa, Naoki
AU - Nagasawa, Tohru
AU - Narushima, Takayuki
AU - Nakano, Takayoshi
N1 - Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2008/12
Y1 - 2008/12
N2 - In this study, we focused on the fabrication of titanium single crystal by the floating zone melting process under the Ar gas flow atmosphere where partial pressure of oxygen was kept to be extremely low around Po1 = 10~23 atm, by using the newly developed oxygen reduction system. In the obtained single crystal, distribution of solute oxygen atoms exhibited a peculiar gradient. In the portion gained in an early stage of the crystal growth, the oxygen content showed a higher value of about 1600 ppm than that in the mother ingot of 980 ppm. As the crystal growth proceeded, however, the oxygen content showed a gradual decrease, and in the final portion of the crystal growth, the oxygen content dropped down to 660 ppm. Such a gradient of oxygen composition was not detected in Ti single crystals fabricated under the standard and usual Ar gas flow condition. Owing to the unique gradient of oxygen content under extremely low oxygen partial pressure, the Vickers hardness in the single crystal showed a gradual decrease along the crystal growth direction.
AB - In this study, we focused on the fabrication of titanium single crystal by the floating zone melting process under the Ar gas flow atmosphere where partial pressure of oxygen was kept to be extremely low around Po1 = 10~23 atm, by using the newly developed oxygen reduction system. In the obtained single crystal, distribution of solute oxygen atoms exhibited a peculiar gradient. In the portion gained in an early stage of the crystal growth, the oxygen content showed a higher value of about 1600 ppm than that in the mother ingot of 980 ppm. As the crystal growth proceeded, however, the oxygen content showed a gradual decrease, and in the final portion of the crystal growth, the oxygen content dropped down to 660 ppm. Such a gradient of oxygen composition was not detected in Ti single crystals fabricated under the standard and usual Ar gas flow condition. Owing to the unique gradient of oxygen content under extremely low oxygen partial pressure, the Vickers hardness in the single crystal showed a gradual decrease along the crystal growth direction.
KW - Composition gradient
KW - Crystal growth
KW - Extremely low oxygen partial pressure
KW - Floating zone
KW - Oxygen content
KW - Single crystal
KW - Titanium
KW - Vickers hardness
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U2 - 10.2320/jinstmet.72.928
DO - 10.2320/jinstmet.72.928
M3 - Article
AN - SCOPUS:58649118403
VL - 72
SP - 928
EP - 934
JO - Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
JF - Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
SN - 0021-4876
IS - 12
ER -