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摘要
Spark plasma sintering (SPS) was a promising method for repairing refractory waste targets. In this study, Mo-10Nb powders and Mo-10Nb waste targets were joined at variable temperatures by SPS for 10 min. The effects of temperatures (1400-1650 degrees C) on the interfacial microstructure, thermal conductivity, and mechanical properties were studied. It was unveiled that more Nb dissolved into the Mo lattice as temperature raised and all interfaces were defect-free. The electron back-scattered diffraction images revealed that the grain size of the powder-sintered body at 1550 degrees C was close to the original waste target. Besides, "90 degrees" junctions were formed on the interface at 1400 degrees C, part of "120 degrees" configurations were formed at 1450-1500 degrees C, and the interface was fused at 1550-1650 degrees C. The evolution of the interface structure was related to the intrinsic diffusion coefficient (D) of Mo-10Nb. The D calculated from SPS densification data verified that D increased with the increase in joining temperatures, which enhanced the atomic flux through the interface and facilitated the interface fusion. Additionally, the combination of effects (grain size and porosity) improved the thermal conductivity. Besides, the relative density and micro-hardness raised with increasing temperatures. The bending strength increased first and then declined at 1650 degrees C, and the failure position was also different. Based on the relevant analysis, it was determined that the optimum temperature for repairing the waste refractory Mo-10Nb target was 1550 degrees C.
