Pre-alloyed NbSS solid-solution fine powder with a D50 size of 3.3μm, pre-alloyed Nb5Si3 and Cr2Nb compound powders with D50 size respectively of 22.1μm and 23.5μm were used as raw materials, and two-phase NbSS/Nb5Si3 alloy and three-phase NbSS/Nb5Si3/Cr2Nb alloy were fabricated by Spark Plasma Sintering (SPS). The microstructure, mechanical properties and oxidation behavior at room and/or high temperatures were investigated. The results show that the microstructure of the NbSS/Nb5Si3 alloy consists of the NbSS matrix and the uniformly distributed Nb5Si3 islands. As for the NbSS/Nb5Si3/Cr2Nb alloy, the NbSS phase tends to connect to be the matrix, while the Nb5Si3 and Cr2Nb blocks scatter in the NbSS phase. Fracture toughness KQ at room temperature of the two-phase and three-phase alloys are 15.0MPa·m1/2and 11.3 MPa·m1/2, respectively. The NbSS phase is found to fail in a dimple mode under bending, which is greatly beneficial to KQ of the bulk Nb-Si based alloys; while the Nb5Si3 and Cr2Nb phases fracture in a brittle mode. At 1250℃, the compressive strength of the NbSS/Nb5Si3/Cr2Nb alloy is higher than that of the NbSS/Nb5Si3 alloy, whereas it is contrary at 1350℃. The Cr2Nb phase plays a positive role in oxidation resistance at high temperature. Air exposed at 1250℃ for 100h, the oxidation mass gain of NbSS/Nb5Si3 alloy is 233mg/cm2, greater than 175mg/cm2 of the NbSS/Nb5Si3/Cr2Nb alloy.
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