块状相变  

Massive Transformation

作　　者：徐祖耀[1] 

机构地区：[1]上海交通大学,上海200030

出　　处：《热处理》2003年第3期1-9,共9页Heat Treatment

摘　　要：概述块状相变研究的进展 ,包括该相变的特征、发生条件及相界结构。块状相变可以定义为 :成分不改变、通过相界扩散的形核—长大型相变 ;相变包括结构改变和有序化 ,其产物一般呈块状显微组织 ,但有时也呈平面边界 ,与其长大的母相晶粒不具完整的位向关系 ,与母相不具点阵对应。讨论块状相变热力学上的两种观点 :上限温度为同成分两相的Gibbs自由能相等的温度T0 及以α/α +γ平衡相界为限制温度 ,本文作者倾向于前一观点。块状相变动力学及相变产物的形态决定于相界结构。阐述相界结构的研究进程。晚近研究结果已揭示相界的共格程度决定于特殊相界面的位向 ,从非共格到一维共格。提出对相界微观结构及其动态、定位考察以及相变产物一些性质研究的展望。The progress in massive transformation,involving the characteristics and required conditions for the occurrence of the transformation and the interface structure, is generally described.Massive transformation may be defined as a partitionless transformation with nucleation and growth by means of interphase boundary diffusion.The transformation involves structural change and ordering and generally yields a massive microstructure,but sometimes the morphology of the product phase shows plane—boundary.There is no complete orientation relationship and lattice correspondence between the product phase and the parent phase.Twopoints of view on thermodynamics of the massive transformation,i.e(1)the limited temperature is T o,the temperature at which the Gibbs free energies of the parent phase and the product phase are equal,and(2)the equilibrium phase boundary α/α+γ is the limited temperature,are discussed.The present author prefers the former one.Kinetics and the morphology of the product phase of the massive transformation are determined by the structure of interphase boundaries.Progress in the study of interphase structure is presented.Recent results revealed that the coherency of the interphase boundary depends on the orientation of a particular interphase plane,from incoherent to one-dimensional coherent.Perspective in dynamic in-situ observation of the microstructure of the interphase boundaries,as well as survey of the properties of the product phase in various alloys,are suggested.Phase diagrams related to the massive transformation are summarized.

关 键 词：块状相变 热力学 相界扩散 相界结构 形核 热处理 

分 类 号：TG151[金属学及工艺—热处理] TG111.5[金属学及工艺—金属学]