TiC在Ti_2CS上形核生长的电镜观察及其取向关系的测定

TEM observation of TiC precipitates nucleated on Ti_2CS and determination of orientation relationships

为探讨与控制薄板坯连铸连轧工艺条件下碳化钛在钢中的析出行为,应用透射电子显微术(TEM)研究了纳米尺度TiC和Ti2CS析出相的结构及取向关系.结果表明,实验钢中Ti2CS的析出温度较TiC的高,先析出的Ti2CS可作为TiC的非自发形核地点.实验观察到细小TiC粒子在Ti2CS上生长的现象.电子衍射和X射线能谱(EDS)分析表明:TiC和Ti2CS之间的取向关系为{001}Ti2CS∥{111}TiC,〈100〉Ti2CS∥〈011-〉TiC.在TEM下还观察到以孪晶形式存在的TiC,孪晶面为(1-11-)面.总之,在钢中先行析出的Ti2CS和TiC粒子都可能成为新生成TiC的非自发形核地点,孪生和外延生长是TiC沉淀的两种重要机制.

In order to investigate and control the precipitation behavior of titanium carbide in Ti-steels produced by thin slab casting and rolling（TSCR）,the structure and orientation relationship of TiC and Ti2CS were studied by transmission electron microscopy（TEM）.The results show that in the experimental steels Ti2CS precipitates at relatively higher temperature than TiC.Ti2CS precipitated previously can act as heterogeneous nucleation sites for TiC.Many tiny TiC particles grow from Ti2CS.The results of electron diffraction and X-ray energy dispersive spectroscopy show that the orientation relationship between TiC and Ti2CS is {001}Ti2CS{111}TiC,〈100〉Ti2CS〈011^-〉TiC.There are also some titanium carbide particles with twinned structure in the steels and the twinning plane is（1^-11^-）.Therefore,the previous precipitates,either Ti2CS or TiC,can provide preferential sites for latter TiC nucleation.Both of the twinning and epitaxial growth are important mechanisms for precipitation of titanium carbide in the TSCR steels.