Abstract:In this paper, (Ti, Zr)5Si3/TA19(C, N) composites were fabricated via low-energy mechanical milling and spark plasma sintering. The microstructure and mechanical properties of (Ti, Zr)5Si3/TA19(C, N) composites were systematically studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe micro-analysis (EPMA) and electronic universal testing machine. The results showed that the grains of (Ti, Zr)5Si3/TA19(C, N) composites were gradually refined with the increase in the content of the reinforcing phase. When the content of graphite phase carbon nitride (C3N4) reached 0.7% (mass fraction), the thickness of α lamellae increased obviously, the matrix changed from widmanstatten structure to near-equiaxed structure, and α phase changed from lamellar structure to short rod structure. At room temperature, when the addition of Si and C3N4 was 0.3% and 0.2%, respectively, (Ti, Zr)5Si3/ TA19(C, N) composite achieved a good combination of strength and plasticity, and its tensile strength reached (1280.3±14) MPa, which was 15.6% higher than that of TA19 alloy. At this point, the fracture elongation remained 4.8%±0.6%. With the increase in the content of the reinforcing phase, the silicide precipitated in the matrix and distributed at α/β phase boundary, which played a pinning role in the matrix structure. In addition, the interstitial solid solution of C and N elements also effectively improved the strength of the composites, but excessive C and N elements would seriously damage the plasticity of the composites, resulting in a significant decrease in the elongation at break at room temperature. The improvement in mechanical properties of the composites of composites was mainly attributed to grain refinement, solid solution strengthening and second phase strengthening.