球墨铸铁中含Ti夹杂物的研究

借助扫描电镜观察球铁中夹杂物并对其进行能谱分析,结合热力学计算结果研究了球铁中钛元素的热力学、动力学行为和含Ti夹杂物的组成、形貌、尺寸及分布状态.结果表明:在1 373～1 873 K,球铁中能够形成TiC、TiN、TiS、TiO2、Ti2O3和Ti3O5夹杂物,其中氧化物最易形成,其次为硫化物、氮化物和碳化物；球铁中存在TiC单相夹杂物,Ti-La-Ce-Mg-C-N-S稀土复相夹杂物和Ti-Mg-Si-C-N、 Ti-V-Si-C等复相夹杂物,夹杂物以多边形为主,尺寸在1～3 μm,分布在珠光体与铁索体基体中,少量夹杂物分布在晶界处.在钛与稀土元素的中和反应和含钛氧化物与碳的还原反应共同作用下,球铁中能形成大量富集稀土元素的含Ti复相夹杂物.

Study on Ti-Inclusions in Ductile Iron

Inclusions in ductile iron were observed and studied by using of scanning electron microscope(SEM)and energy spectral analysis in this paper.Combining with the thermodynamic calculation results,the thermodynamic and kinetic behavior of Ti element,the constitution,morphology,dimension and distribution of Ti-inclusions in ductile iron were also studied.The results show that TiC,TiN,TiS,TiO2,Ti2O3 and Ti3O5 inclusions can form in ductile iron at 1 373-1 873 K.Among these inclusions,the oxide is the most easily to form,followed by sulfide nitride and carbide.TiC single-phase inclusions,Ti-La-Ce-Mg-C-N-S multi-phase inclusions of RE,Ti-Mg-Si-C-N,Ti-V-Si-C and other multi-phase inclusions exist in ductile iron.Most of inclusions are polygonal with a size of 1-3 μm and distribute in pearlite and ferrite matrix,while a small amount of them distribute at the grain boundaries.Large amount of multi-phase inclusions contained Ti and rich in RE,are formed in ductile iron under the action of neutralization reaction of Ti and RE,combined with the reduction reaction between oxides of Ti and carbon.