关于贝氏体形核和台阶机制的讨论--与徐祖耀院士等商榷

一些合金固溶化(或淬水)后在预贝氏体(孕育)期内等温淬火(或时效)，既保持高温时形成的晶体缺陷，又产生新的晶体缺陷。母相中由于溶质原子扩散而在缺陷处发生偏聚，则形成贫／富溶质微区，即类拐点(spinoclal—like)分解。当贫溶质微区成分作为Ms，其温度等于或高于等温淬火(或时效)温度时，贝氏体将以马氏体样切变形核，故贝氏体是在溶质原子扩散控制下切变形核。在TEM温台试验中未发现台阶生长机制，界面上巨型台阶是贝氏体增宽(厚)速度差异所致。

Mechanism of Bainitic Nucleation and Ledge Growth--Discussion with Professor Hsu T Y(XU Zu-yao)

During pre-bainitic(incubation)period of isothermal treatment(or aging) after solution treatment(or quenching), not only are the crystal defects formed at high temperature maintained, but new crystal defects can also be generated in some alloys. Due to the segregation of the solute atoms near defects through diffusion, this leads to the formation for the depleted/enriched solute regions in the parent phase, i.e, spinodal-like decomposition. It is proposed that when the M S temperature of the solute depleted regions is equal or higher than isothermal(or aged) temperature, the bainitic nucleation occurs within the solute depleted regions in the manner of martensitic shear.The ledge growth mechanism of bainite disappears in experiments.Superledge at the baintic boundary can be formed by the diffence of the moving rate for the widening(thickening) of the bainitic lath.