摘要
从三元系自由能对成分的Taylor展开,导出三元调幅分解的热力学判据为G_(xx)(δ_x)~2+2G_(xy)δ_xδ_y+G_(yy)(δ_y)~2<0,据此引出调幅分解的各种条件:当G_(xx)<0,G_(xy)~2-G_(xx)G_(yy)<0,为不受成分起伏方向约束的不稳定分解,当G_(xx)<0,G_(xy)~2-G_(xx)G_(yy)>0以及G_(xx)>0,G_(xy)~2-G_(xx)G_(yy)>0或G_(xx)=0均为受成分起伏方向约束的不稳定分解,相应的成分起伏δ_x,δ_y需满足一定的条件。由此可以解释调幅分解过程中发生的成分转动现象.以Cu-Ni-Fe系为例根据以上三元调幅分解的判据由计算机计算不稳定分解区域的范围与文献报道的实验结果相符。
By expanding the Gibbs free energy of ternary system into a Taylorseries with respect to the composition, a thermodynamical criterion of spinodal de-composition is conducted as G_(xx)(δ_x)~2 + 2G_(xy)δ_xδ_y + G_(yy)(δy)~2<0, from which, various con-ditions of spinodal decomposition are discussed. When G_(xx)<0, G_(xx)~2-G_(xx)G_(yy)<0, it iscalled as unstable decomposition unrestricted by the direction of composition fluctu-ation; when G_(xx)<0, G_(xy)~2-G_(xx)G_(yy)>0, or G_(xx)>0, G_(xy)~2-G_(xx)G_(yy)>0, as well as G_(xx)=0,are all considered as unstable decomposition restricted by the direction of composi-tion fluctuation δ_x and δ_y. The phenomenon of turning round in composition duringspinodal decomposition is attempted to be explained from above poiat of view. Thecomputer calculated ranges of unstable decomposition according to the criterion ofspinodal decomposition on Cu-Ni-Fe ternary system is consistent with the experi-mental results obtained from literatures.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
1990年第5期B303-B309,共7页
Acta Metallurgica Sinica
基金
国家自然科学基金
关键词
Cu-Ni-Fe合金
热力学
判据
调幅
spinodal decomposition
thermodynamics
criterion
CuNiFe system
