摘要
通过对多种工业用钢贝氏体碳化物的电镜观察和理论分析,结果表明:贝氏体碳化物呈短棒状、层片状、纤维状、楔形等形形色色的形貌。在贝氏体铁素体(BF)内部不具备形成碳化物的条件。贝氏体碳化物在BF/γ相界面上形核,并沿着相界面长大。上贝氏体的θ(Fe,M)3C与铁素体片条大体上平行排列;下贝氏体碳化物以楔形长入铁素体亚单元之间,或长入富碳奥氏体中,并且与铁素体主轴方向呈现交角分布。上、下贝氏体中碳化物停止长大后均可被铁素体包围,表现在形态上是分布在贝氏体铁素体中。贝氏体碳化物形成过程中,碳原子长程扩散,而铁原子和置换原子以热激活跃迁的方式,沿着界面位移,实现晶格改组。
The morphology of bainitic carbides（CBF） in various industrial steels was examined by scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.The results show that the bainitic carbides present in different shapes of short bar,lamella and wedge in the steels. The carbide can not nucleate from inside of bainitic ferrite because the ferrite can not provide the condition for nucleation of the carbide. Bainitic carbide nucleates at boundaries of BF/γ, and grows up into the sub-units of bainitic ferrite or austenite along the boundaries. θ（ Fe, M）3 C and ferrite of upper bainite arranges parallesly, and the wedge-shaped carbides in lower bainite grow up into the sub-units of the ferrite or carbonrich austenite, and the elangated carbides show a certain degree from the plate-lengthening direction of ferrite. Upper or lower bainitic carbide stops the growth when it is surrounded by the ferrite.The carbon atoms move by long-range diffusion and iron atoms and substitutional atoms transfer by thermal activation way along the boundaries in the formation process of bainitic carbides, this made the crystal lattice repacked.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2008年第1期32-37,46,共7页
Transactions of Materials and Heat Treatment
基金
内蒙古自治区高等学校科学研究项目(NJ06073)
关键词
贝氏体
碳化物
扩散
热激活
bainite
carbide
diffusion
thermal activation
