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采用熔融玻璃净化法研究了深过冷Fe-10at％Ni合金中bcc亚稳相的形成、形貌及其凝固行为。确定了在Fe-10at％Ni合金中得到亚稳相的临界过冷度为95K。随着过冷度增大,亚稳相的相分数也随之增加。透射电子显微镜分析结果表明,初生亚稳相的形貌与过冷度无关,均为枝晶。采用经典形核理论分析了过冷Fe-10at％Ni熔体中bcc(δ)相和fcc(γ)相竞争形核时的临界激活能和稳态形核率。借助BCT模型计算了bcc(δ)和fcc(γ)相的生长速度与过冷度的关系,结果表明当过冷度较大时,亚稳bcc相的生长速度明显滞后于fcc相的生长速度。
The formation, morphology and solidification behavior of bcc metastable phase in deep undercooled Fe-10at% Ni alloy were studied by the glass-melting method. The critical undercooling of metastable phase in Fe-10at% Ni alloy was determined to be 95K. As the undercooling increases, the phase fraction of the metastable phase also increases. Transmission electron microscopy analysis showed that the morphology of primary metastable phase has nothing to do with the degree of undercooling, are dendrites. The critical activation energy and steady-state nucleation rate of nucleation of bcc (δ) phase and fcc (γ) phase in undercooled Fe-10at% Ni melt were analyzed by classical nucleation theory. The relationship between growth rate and undercooling of bcc (δ) and fcc (γ) phases was calculated by BCT model. The results show that when the undercooling is large, the growth rate of metastable bcc phase lags behind the growth rate of fcc phase .