聚碳硅烷原位自生增强钛基复合材料的组织及性能

Microstructure and Mechanical Properties of Polycarbosilane In-situ Reinforced Titanium Matrix Composites

以低氧氢化脱氢钛粉和陶瓷先驱体聚合物聚碳硅烷(PCS)为原料,通过粉末冶金工艺原位自生制备高强高塑钛基复合材料,探究了PCS的引入对钛基复合材料的控氧效果、烧结致密化过程、基体显微组织和力学性能的影响规律。结果表明:采用湿混包覆工艺可以将PCS包覆于Ti粉表面,有效控制材料制备过程中的氧增,其中制备的Ti-1.0%PCS(质量分数,下同)复合材料的氧质量分数为0.21%~0.24%,显著低于未经处理的CP-Ti样品(0.36%~0.41%)。在烧结过程中,PCS受热分解并与Ti基体原位反应生成TiC颗粒,弥散分布在基体中,而Si元素则固溶于Ti基体。PCS的引入对Ti基体的性能具有明显的改善作用,经1200℃/2 h烧结制备的Ti-1.0%PCS复合材料致密度达到98.4%,洛氏硬度为37.1 HRC,屈服强度为544 MPa,抗拉强度为650 MPa,延伸率为14.5%,其综合性能指标显著优于CP-Ti样品。

The in-situ reinforced titanium matrix composites were fabricated using low-oxygen hydride-dehydride(HDH)Ti powders and polycarbosilane(PCS)via a powder metallurgy method,including solution-assisted wet mixing and pressureless sintering.The effects of PCS addition on the oxygen inhibition,sintering densification,microstructure and mechanical properties of the composites were investigated.The results show that the solution-assisted wet mixing process makes the Ti powders coated with PCS,which can effectively control the oxygen contamination.The oxygen content of the fabricated Ti-1.0%PCS(mass fraction)composite is 0.21%~0.24%,much lower than 0.36%~0.41%of CP-Ti.During sintering,the pyrolysis products of PCS can react with Ti matrix to in-situ synthesize TiC particles,while Si element is dissolved in matrix.The incorporation of PCS can improve the mechanical properties of the Ti matrix.The Ti-1.0%PCS composite sintered at 1200℃for 2 h possesses the best mechanical properties,with a relative density of 98.4%,a Rockwell hardness of 37.1 HRC,a yield strength of 544 MPa,an ultimate tensile strength of 650 MPa,and an elongation of 14.5%.Therefore,the composite is obviously superior to CP-Ti in comprehensive performance index.