Al₂O₃-TiC_p(AT)复相陶瓷材料以其优异的综合力学性能而被广泛用作金属切削刀具材料。针对AT材料传统烧结方法在能耗及周期方面的局限, 本工作利用激光定向能量沉积技术开展了AT复相陶瓷材料直接增材制造的研究, 系统探讨了不同TiC_p比例对复相陶瓷材料微观结构和力学性能的影响。结果表明TiC_p颗粒均匀分布在成型样件的基体中, 掺杂TiC_p细化了Al₂O₃晶粒。同时, 由于TiC_p与Al₂O₃基体的热膨胀失配引起裂纹出现偏转、贯穿颗粒等现象, 消耗了裂纹扩展能量, 进而有效抑制了AT材料直接增材过程中的裂纹扩展行为。掺杂TiC_p颗粒对熔池形成冲击, 在一定程度上加快了气体的逸出速率, 进而提高了材料的相对密度。但TiC_p含量过高将加剧其与Al₂O₃基体在高温时的化学反应, 生成的气体使复合材料中出现较大气孔并降低了材料部分力学性能。TiC_p质量分数为30%的复合材料的相对密度达到96.64%、平均显微硬度达到21.07 GPa和断裂韧性达到4.29 MPa·m^1/2。

Al₂O₃-TiC_p (AT) composites are frequently used as materials for metal cutting tools due to their superior mechanical properties. However, conventional sintering methods for AT materials have limitations in terms of energy consumption and cycle time. Therefore, in this study, direct additive manufacturing of AT composite ceramic materials was investigated using laser directed energy deposition technology. Effects of different TiC_p ratios on the microstructure and mechanical properties of composite ceramic materials were explored. The results demonstrate that TiC_p particles are uniformly distributed throughout the matrix of the fabricated samples, leading to refinement of Al₂O₃ grains. Stress induced by mismatch between the thermal expansion coefficients of TiC_p and the Al₂O₃ matrix causes cracks to deflect and penetrates the particles, which consumes the crack extension energy and effectively suppresses the cracks in AT materials. Additionally, doping TiC_p particles affects the molten pool by increasing the gas escape rate and improving the material density. However, high TiC_p content aggravates the reaction with Al₂O₃ at high temperature, resulting in generation of gas and large pores in the composite material, which reduces the mechanical properties. Composites with TiC_p mass fraction of 30% exhibit the best mechanical properties, with a relative density of 96.64%, microhardness and fracture toughness of 21.07 GPa and 4.29 MPa·m^1/2.