1 Experimental The G.S.used for TEM analysis were extracted from the cast iron conta- ining4.2%C,1.07%Si,0.005%P,0.003%S,0.19%Mn and 0.32%Ce melted in a carbon-tube furnace under argon atmosphere. Foil specimen preparation:First,each G.S.were inlaid on a polished plane in single layer,then polished from the tcp and the bottom till thinned down to about 0.2um in thick,and then fixed in a 3mm in diameter Cu suppor- ting net.Finally,using the Gatan-600B ionic thinner the specimens were thinned to have thin area suitable for TEM observations. The TEM observations,centre dark field (CDF),bright field (BF)and selected area electron diffraction (SAD)were performed with a Hitachi-800 analytical electron microscope. 2 Results and Discussions The microstructure of G.S.is shown in Fig.1.There is a typical annular graphite in the well-developed G.S.sections at low magnifications.As the previous paper mentioned t8],most of G.S.have a nucleus composed of a group of particles of cerium oxide or cerium oxysulfide. The detailed studies of the structure of G.S.are shown in Fig.2 and Fig.3,respectively.From the Fig.2,there are platelets with about 8-60nm in radial (see Fig.2b),along the periphery of the G.S.without apparent zigzag.The [001]direction of the platelets oriented approximately radially. And they have a small misorientation each other based on 002*diffraction spot extended to an arc (see Fig.2a).Fig.3 shows the other structure with 120 and 140 chevron formed from platelet aggregates towards the centre of the G.S. Fig.1 The microstructure of a Fig.2 The microstructure and SAD annular graphite spherutites. patterns of the graphites. 1 582注 犷，丈 二 。 。 · ， ， ， ， 一 · ， · ， 。 拼 ， 〕 一 ， 一 。 ， ， 一 · 。 · · 一 · · · ， 一 · 一 ， ， 一 一 ， · · 〔 〕 · 一 一 “ 。 口户喊 入 「 一 · 尹 户