原位TiC颗粒增强铁基复合材料及其组织形成机理

IN SITU TiC PARTICULATES REINFORCED FERROUS MATRIX COMPOSITE AND ITS MICROSTRUCTURE FORMING MECHANISM

研究了反应铸造工艺制备的原位TeCp／Fe复合材料的组织和性能，并探讨了复合材料的组织形成机理．结果表明：原位合成的TiC颗粒尺寸细小（4．48μm）、数目多（2169个／mm2）且在珠光作基体中分布均匀；TIC颗粒与基体的界面干净，无间隙和界面反应产物生.成这些组织特点使所制备的复合材料具有如下平均性能：硬度HRC＝42冲击韧性αk＝8．6J／cm2，抗拉强度σb＝422MPa，延伸率δ＝1．6％．分析认为：TiC颗粒是在Fe－Ti－C合金熔体的等温反应过程中形成的，而有害化合物R3C和Fe2Ti则在蒋体的凝固过程中桥出；对熔体进行Cu，Ni微合金化及孕育处理可防止有害化合物的形成，从而提高复合材料的性能．

The microstructures, mechanical properties of in situ TiCp/Fe composites fabricated by areactive casting process have been investigated, and the formation mechanism of the composite microstruc-tures has also been analysed. The results show that in situ TiC particulates, which distribute homogenously in pearlite matrix, are finer in size (4.48μm) and more in number (2169/mm2). The interface betweenTiC particulates and matrix is clear, no illterface gap and reactive product are found. As above features, theaverage properties of the prepared composites are as follow: hardness HRC=42, impact toughness ak=8.6J/cm2, ultimate tensile strength σb=422 MPa and elongation δ=1.6%. It is thought that TiC particulatesare formed dtiring the temperature-holding for the Fe-Ti-C melt, whereas the harmful compounds Fe3Cand Fe2Ti are precipitated during the solidification process of the melt. The treatmellt of Cu and Nimicroalloying and inoculation for the melt can improve the mechanical properties of the composites, owingto the fact that the precipitation of harmful compounds is prevented effectively.