Phase equilibria in the Ti-Al binary system

被引：249
作者：
Ohnuma, I [1 ]
Fujita, Y [1 ]
Mitsui, H [1 ]
Ishikawa, K [1 ]
Kainuma, R [1 ]
Ishida, K [1 ]
机构：
[1] Tohoku Univ, Grad Sch Engn, Dept Mat Sci, Sendai, Miyagi 9808579, Japan
来源：
ACTA MATERIALIA | 2000年 / 48卷 / 12期
关键词：
titanium; phase equilibria; thermodynamics; order-disorder phenomena; calculation of phase diagrams (CALPHAD);
D O I：
10.1016/S1359-6454(00)00118-X
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
New experimental results on the phase equilibria between the beta-Ti (A2), alpha-Ti (A3), alpha(2)-Ti3Al (D0(19)) and the gamma-TiAl (L1(0)) phases in the Ti-Al system using specimens with low levels of oxygen are presented. The results obtained on the alpha/gamma and the alpha(2)/gamma equilibria are in good agreement with the previous experimental and calculated phase boundaries, while the ones obtained on the alpha/beta equilibrium deviate significantly from the previously proposed phase diagram. It is confirmed that the beta phase held extends to higher aluminum contents and that the width of the alpha+beta two-phase region is very narrow, less than 1 at.% Al. The presence of the A2/B2 order-disorder transition in the beta phase is also confirmed by a combination of differential scanning calorimetric (DSC) analysis and extrapolation of ordering phase boundaries from the Ti-Al-X (X = Cr, Fe) ternary systems. A thermodynamic analysis has been carried out taking into account the ordering configurations in the beta-Ti (A2)/beta(2)-TiAl (B2), f.c.c.-Al (Al)/gamma-TiAl (L1(0)) and alpha-Ti (A3)/alpha(2)-Ti3Al (D0(19)) equilibria. It is proposed that the anomalous alpha/beta equilibrium is due to the A2/B3 ordering reaction. (C) 2000 Acta Metallurgica Inc. Published bl, Elsevier Science Ltd. All Fights rt ser, ed.
引用
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页码：3113 / 3123
页数：11
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