TiC_P/1Cr18 Ni9复合材料显微组织和力学性能的研究

Study on Microstructure and Mechanical Properties of Cast in situ TiC_P/1Cr18Ni9 Composite

采用原位合成铸造法制备了TiC颗粒增强 1Cr18Ni9钢基复合材料。试验结果表明 :TiC颗粒在基体中分布均匀 ,与基体结合良好且无团聚现象 ,复合材料的室温、高温强度与基体相比均有提高 ,但塑性和冲击韧性有所下降。

In the present investigation TiC P/1Cr18Ni9 composite with 5vol.% TiC particles is prepared by in situ reaction during melting process. The shape, size and distribution of TiC particles in the composite are observed. The microstructure and properties of the composite are studied in detail, too. Experimental results show that TiC particles distribute evenly in the matrix and no apparent segregation of TiC particles are observed. Most of TiC particles seem to be spheres with size of 3～6μm. Moreover, the addition of TiC particles greatly reduces grain size of the matrix, but does not apparently changed microstructure of the matrix. In order to evaluate the strength and the ductility of the composite, tensile tests are carried out at room temperature and high temperature of 600℃ and 700℃ separately. As is seen from the results, the addition of TiC particles apparently strengthens the matrix alloy. The strengthening mechanism might be deduced from the difference of thermoelasticity between the TiC particles and the matrix 1Cr8Ni9. Since TiC particles are embeded firmly in the matrix and their interfaces with matrix is clean, so it causes a large stress and hardens the composite. The strength of composite would arise according to Hall Patch equation.Compared with matrix, TiC P/1Cr18Ni9 composite has low wear loss only about 35% of the matrix's. This may be attributed to the high hardness of TiC particles resisting effectively the ploughing and cutting to matrix. The results of high temperature creep test at 600℃ show that the composite has a longevity as three times as thats of matrix alloy. The composite has higher toughness but lower ductility compared with the matrix. The fracture and wear morphology by SEM is consistent with the results of mechanical test. So the TiC P/1Cr18Ni9 composite is reasonable to instead the stainless steels being used in conditions where both wear and corrosion problems are encountered.