Effects of Al addition on the microstructure and properties of Nb/Nb₅Si₃ in situ composites fabricated via spark plasma sintering

Abstract

Dense Nb/Nb₅Si₃ composites were fabricated via spark plasma sintering technology using Nb, Si, and Al elemental powders as raw materials. The microstructures of the synthesised composites were analyzed through scanning electron microscopy, X-ray diffraction, and electron probe microanalysis. The results show that the composites consisted of residual Nb particle phase and Nb₅Si₃ phase. The microstructure of the Nb/Nb₅Si₃ in situ composites was evidently affected by Al addition, which prompted the formation of the Al₃Nb₁₀Si₃ phase. In addition, the Rockwell hardness of the composites decreased with the increase in Al additions. The Rockwell hardness of Nb-20Si is 60HRC, which decreased to approximately 52.7 HRC when the Al content increased to 15 at%. The oxidation resistance of the Nb/Nb₅Si₃ in situ composites significantly improved with the increase in Al addition.

Keywords

spark plasma sintering / Nb/Nb₅Si₃ composites / oxidation resistance / microstructure

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