Ti3SiC2含量对热处理态(Ti5Si3+TiC)/TC4复合材料组织及力学性能的影响

Effects of Ti 3SiC 2 Content on the Microstructure and Properties of Heat Treated(Ti 5Si 3+TiC)/TC4 Composites

针对钛基复合材料中增强相易团聚的问题,采用固溶加时效的热处理工艺对其组织进行优化,研究了Ti3SiC2含量对材料微观组织及力学性能的影响。通过扫描电子显微镜和能谱分析仪观测了不同Ti3SiC2含量的复合材料的微观组织形貌,并探究热处理过程中基体组织的细化机制与增强相的析出规律,进而分析了室温力学性能的变化规律。实验结果表明:随着Ti3SiC2含量的增加,固溶处理后的原始晶粒尺寸大幅度减小,时效处理后的片状α相和团簇组织的平均尺寸也呈递减趋势;Ti5Si3颗粒在β相内、α/β相界处和α相内均有析出,其含量随Ti3SiC2质量分数增加而递增;(Ti5Si3+TiC)/TC4复合材料的屈服强度和抗压强度均明显高于相同热处理条件下的基体TC4合金,当Ti3SiC2的质量分数为8%时,复合材料的屈服强度和抗压强度分别达到1 930 MPa和2 500 MPa,综合力学性能最优;当Ti3SiC2的质量分数继续增加至10%时,复合材料的力学性能难以通过固溶和时效处理进一步改善。

To improve the aggregation of reinforcements in titanium matrix composites,solid solution and aging treatments were used,and the effects of Ti 3SiC 2 content on the microstructure and mechanical properties of the composites were studied.Scanning electron microscope and energy spectrum analyzer were adopted to observe the microstructures with different Ti 3SiC 2 contents.The refining mechanism of the matrix and the precipitation of the reinforcements during the heat treatment were investigated.The results show that the original grain size of as-treated composites decreases significantly with the Ti 3SiC 2 content,and the grain size of lamellaαphase also reduces.Ti 5Si 3 particles precipitate in theαandβphases and at the interface ofαandβphases,and its content increases with Ti 3SiC 2 content.The yield strength and compressive strength of the composites are significantly higher than that of TC4 alloy under the same heat treatment condition.When the mass fraction of Ti 3SiC 2 is 8%,the yield strength and compressive strength of(Ti 5Si 3+TiC)/TC4 composite reach 1930 MPa and 2500 MPa,respectively,and the best comprehensive mechanical properties are obtained.When the mass fraction of Ti 3SiC 2 increases continuously to 10%,the mechanical properties of the composites cannot be further improved through solid-solution strengthening and aging treatment.