CVM CALCULATION OF THE PHASE-DIAGRAM OF BCC FE-CO-AL

被引:56
作者
COLINET, C
INDEN, G
KIKUCHI, R
机构
[1] MAX PLANCK INST IRON RES, W-4000 DUSSELDORF, GERMANY
[2] UNIV CALIF LOS ANGELES, DEPT MAT SCI & ENGN, LOS ANGELES, CA 90024 USA
来源
ACTA METALLURGICA ET MATERIALIA | 1993年 / 41卷 / 04期
关键词
D O I
10.1016/0956-7151(93)90159-P
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The Cluster Variation Method (CVM) in the irregular tetrahedron approximation is used to calculate the phase diagram of the b.c.c. ternary system Fe-Co-Al. At first paramagnetic states are treated and chemical pair interactions between first and second nearest neighbours are taken into account in the calculation. The numerical values for these interactions are taken from separate studies. Complete isothermal sections at T = 1400, 1000, 800, 700, 600, 300 K and several vertical sections are presented. A ternary miscibility gap is found between ordered and disordered phases, (B2 + A2) as well as (D0(3) + A2), and between the two ordered phases B2 and D0(3). This miscibility gap closes at multicritical lines defined by the intersection of the second order critical temperature surfaces with the miscibility gap. In the binary Fe-Co system the Curie temperature is much higher than the critical temperature of chemical ordering. Therefore magnetic interactions cannot be neglected in this system nor in the Fe- and Co-rich ternary alloys. Magnetic interactions have been considered between nearest neighbours in a spin 1/2 treatment. Each element was treated as two components, A up and A down, and the CVM treatment thus dealt with a six component system. For T = 600 K a complete isothermal section is presented which includes the magnetic effects.
引用
收藏
页码:1109 / 1118
页数:10
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