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珠光体转变新机制珠光体转变研究之二
刘宗昌，计云萍
（内蒙古科技大学材料与冶金学院，内蒙古包头014010）
摘要：过冷奥氏体在孕育期内，在贫碳区建构铁素体核胚的同时，在富碳区也建构渗碳体（或碳化物)的核
胚，共同组成珠光体的晶核(F+Fe,C)。铁素体和渗碳体两相是同时同步、共析共生的，不存在领先相。珠光体的形核-长大是以界面扩散为主的扩散性一级相变。珠光体在奥氏体界面等处形核。计算表明，在700～650℃，临界晶核尺寸为150～70nm，临界形核功为155～292J/mol。共析铁素体和共析渗碳体两相与母相奥氏体的相界面是由连续的长大台阶所耦合，F/A、C/A相界面具有半共格结构。铁素体和渗碳体两相依靠共享台阶的侧向迁移而长大，共析共生、协同生长。
关键词：珠光体；珠光体转变；临界晶核；共享台阶；界面扩散；奥氏体
中图分类号：TG111.5
文献标识码：A
文章编号：1008-1690(2017)02-0001-09
NewMechanismofPearliteTransformation-ResearchonPearliteTransformation(Il)
LIUZongchang，JIYunping
( Material and Metallurgy School, Inner Mongolia University of Science and Technology ,
Baotou 014010, Nei Mongol China)
Abstract: During the incubation period of supercooled austenite transformation, while the ferrite embryo is constructed in carbon-depleted zone, the cementite or carbide also is constructed in the carbon-enriched zone, and they constitute together the crystal nucleus of pearlite ( F + Fe, C). Both the ferrite and cementite are eutectoid and symbiotic, there being no the leading phase. The nucleation and growth of pearlite are the diffusible first order phase transformation which proceeds mainly by the aid of interface diffusion. The pearlite nucleates along the crystal grain boundary of austenite or in other places. The calculation shows that the dimension of critical nucleus is about 150 to 70 nm, and that the value of the critical nucleation energy is about 155 to 292 J/mol at 700 to 65o °C. The interface between the eutectoid ferrite or the eutectoid cementite and the parent phase austenite is coupled by the continuous growing steps, and F/A and C/A interfaces are semi-coherent. The ferrite and the cementite grow by lateral migration of the shared steps. The pearlite transformation is a eutectoid-symbiot and synergetic growth process.
Key words: pearlite; pearlite transformation; critical nucleus; shared step; interface diffusion; austenite
过冷奥氏体共析分解为铁素体与碳化物的整合组织，即珠光体转变是一个自组织的过程。按照自然事物的演化规律，系统远离平衡态，奥氏体在一定过冷度（△T)下，必然出现贫碳区与富碳区的涨落，加上随机出现的结构涨落、能量涨落，一旦满足形核条件，则在贫碳区建构铁素体核胚的同时，在相邻富
收稿日期：2016-12-07
碳区也建构渗碳体（或碳化物）的核胚，二者同时同步、共析共生，非线性相互作用，互为因果，共同组成一个珠光体的晶核（F+Fe,C）。这个演化过程属于放大型的因果正反馈机制，它使微小的随机涨落经过连续的相互作用逐级增强，而使原系统（奥氏体）瓦解，建构新的稳定结构，即珠光体，这个过程即为
作者简介：刘宗昌(1940-)，男，河北玉田人，内蒙古科技大学教授，从事相变理论和热处理技术研究，发表论
文290余篇，出版学术专著9部、高等院校教材8部。E-maillzchang75①163.com
《热处理》
万方数据
2017年第32卷第2期
.