Homogeneous and Heterogeneous Mo-Ni Fillers Doped with Nano-Particles

Traditional Mo-Ni fillers for high temperature brazing of refractory materials have been used for various applications for a long time. However, spreading and mechanical properties of these fillers have never been sufficiently studied. Their properties such as the melting point, and flowability through capillary gaps, as well as mechanical properties (in particular the level of brittleness) play a key role in a successful high temperature brazing process. In this study, Mo-Ni eutectic powder fillers have been doped with (i) 3_wt% or consisted of 100_wt% Mo-Ni eutectic nanoparticles (<100 nm), and (ii) 1_wt%, 3_wt% and 5_wt% SiC nanoparticles (<30 nm), thus forming homogeneous or heterogeneous nano-composites, respectively. In this study, these fillers have been used in brazing of (i) Molybdenum to porous Tungsten and (ii) Molybdenum to Molybdenum, respectively. Mechanical properties of re-solidified fillers were studied in comparison with non-doped fillers by using continuous instrumented micro indentation and conventional hardness testing. It is noticed that, compared to a non-doped fillers, (i) fillers with an increasing amount of SiC nanoparticles feature a significant increase in hardness, by up to ~130%; and (ii) fillers with 3 _wt% Mo-Ni nanoparticles feature a slightly increased hardness, while fillers with 100 _wt% Mo-Ni nanoparticles indicate a slight decrease. Moreover, differences in mechanical responses of various phases within the joint domain were identified.