钢的共析分解理论研究的进展  

Progress of Research on Eutectoid Decomposition Theories for Steel

作　　者：刘宗昌[1] 李涛[1] 

机构地区：[1]内蒙古科技大学材料与冶金学院,内蒙古包头014010

出　　处：《热处理》2012年第6期1-13,共13页Heat Treatment

摘　　要：珠光体是共析铁素体和共析渗碳体（或碳化物）构成的整合组织而不是机械混合物。珠光体的形核一长大是以界面扩散为主进行的。过冷奥氏体中会出现贫碳区和富碳区的涨落，加上随机出现的结构涨落、能量涨落，三者非线性的因果正反馈相互作用，导致贫碳区和富碳区分别建构铁素体和渗碳体（或碳化物）的核坯，组成珠光体晶核（F＋Fe3C）。铁素体和渗碳体是共析共生、台阶式协同长大，不存在领先相。计算表明，珠光体临界晶核半径为70—152nm，临界形核功△G=155～292J／mol。“相问沉淀”是珠光体转变产物，应用共析分解的新理论解释了“相间沉淀”过程。珠光体片间距与奥氏体过冷度的关系是非线性的。发现珠光体表面也有浮凸现象，是新旧相比体积不同所致。Pearlite is an intergrative structure consisting of eutectoid ferrite and eutectoid cementite （or carbide） rather than a mechanical mixture. The nucleation and growth of pearlite will mainly perform through interfacial diffusion. Fluctuations of carbon-depleted and carbon-rich areas present in supercooled austenite, random fluctuations of structure and energy and their nonlinear positive feedback will permit ferrite nucleus and cementite （or carbide） nucleus to be formed respectively in the carbon-depleted and carbon-rich areas and to become pearlite （ F ＋ Fe3C） nucleus. Both ferrite and eementite are euteetoid and symbiotic and grow up together, step by step and without prevenient phase. Calculation shows that radius of critical nucleus varies from 70 to 152 nm, and critical nucleation work （△G＊） varies from 155 to 292 J/tool for pearlite. ＂Interphase precipitation＂ arises from pearlite transformation, and its process was explained by a new theory of eutectoid decomposition. Pearlitic interlamellar space bears a nonlinear relation to supercooling degree of austenite. Surface relief phenomenon also exists on the pearlite, and arises from disparity of the old and new phases in specific volume.

关 键 词：过冷奥氏体 珠光体 共析分解 相间沉淀 界面扩散 形核 表面浮凸 

分 类 号：TG151.2[金属学及工艺—热处理]