摘要
应用JEM-2100电镜、QUANTA-400环扫电镜对各钢铁材料马氏体相变的形核进行了观察,发现马氏体不仅可在奥氏体晶内形核,而且可在晶界、相界面、孪晶界等处形核。认为奥氏体转变为马氏体是在缺陷处依靠结构涨落、能量涨落形核,是晶格重构的过程,非切变过程。研究了形成马氏体晶核时的能量变化规律,计算了马氏体晶核的临界尺寸、形核功,得马氏体临界晶核尺寸为7-20 nm,形核功为200-600.Jmol^-1。临界晶核尺寸和形核功理论上合理,与相变形核的一般规律相吻合。
The nucleation of martensite phase transformation in iron and steel was observed by JEM-2100 transmission electron microscope and QUANTA-400 environmental scanning electron microscope.The results show that martensite nucleates not only in austenite crystal grain interior but also at austenite crystal grain boundary,phase interface and twin boundary.It is considered that martensite phase transformation is not shear transformation,but is a crystal lattice reconstruction process from austenite to martensite at the defects depending on structure fluctuation and energy fluctuation to nucleate.At the same time,the energy change during the formation of martensite crystal nucleus was studied,and the critical dimension and the nucleation energy of martensite crystal nucleus were calculated.The results show that the dimension of the martensite critical nucleus in steel is about 7-20 nm and the critical nucleation energy is about 200-600 J·mol^-1.The calculated values are reasonable in theory and are consistent with the general rule of nucleation of phase transformation.
出处
《金属热处理》
CAS
CSCD
北大核心
2010年第11期17-22,共6页
Heat Treatment of Metals
关键词
过冷奥氏体
马氏体
界面
形核功
临界晶核
supercooled austenite
martensite
interface
nucleation energy
critical nucleus
