界面过程控制生长≠扩散控制

The Growth Controlled by Interfacial Atomic Process is not the Equal that Controlled by Diffusion

应用经典扩散理论数学模型及前人和作者测定的数据,对纯铁块状及形成等轴α相的相变动力学进行分析,结果表明,这两种相变都不属于扩散型。将动力学分析取得的相关数据代入界面过程控制相变数学模型,求得γ→α(等轴晶)的激活能为1 93～1 98kJ mol,小于γ铁的自扩散激活能(2 70kJ mol) ,而与其相界扩散激活能相近(1 5 2～1 72kJ mol)。作者认为,Christian将多形性转变、块状转变、再结晶、晶粒长大、有序化等无成分变化的非切变型相变一并划入界面过程控制类是恰当的。由于短程输送涵义易于混淆,不宜用于相变分类。界面过程控制的细节应是“半无序微位移”机制。

The phase transformation kinetics of iron massive transformation and equiaxed α-phase formation was analyzed by classical diffusion theory using the experimental data obtained by previous researchers and that by the present authors. It is shown that both of the two transformations do not belong to the diffusional type. By substitution of the data obtained from kinetics analysis into the mathematical model of the interface control process, the activation energy for the transformation γ→α is calculated to be 193～198kJ/mol, which is less than that for the self-diffusion of γ-iron (270kJ/mol) but much close to that for its interphase-interface (152～172kJ/mol). The authors believe that the classification by J. W. Christian is appropriate, which attributes the shear-free transformations with no changes in composition to those controlled by interfacial process, such as polymorphic, massive, recrystallization, grain growth and ordering. Short-range transfer is subject to confusion in meaning, so it is not suitable to be used in transformation classification. The interface process controlled transformation should take the mechanism of semi-disordered and differential-displacement.