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Multi-doped MgB2 superconductors with excellent critical current density (Jc ) were rapidly synthesized by low-temperature activated sintering with Cu addition as the activator and nano SiC addition as the carbon-based chemical. Combined with microstructure observation and flux pinning force analysis, it is found that the enhancement of Jc (especially at low field) was mainly attributed to the higher density, lower crystallinity and the concentration of Cu activator around the sintered voids. [Copyright &y& Elsevier]

In order to further refine W particles and improve properties of traditional W-Cu alloys, an innovative freeze-drying and subsequent solid phase sintering technology was employed to fabricate ultrafine W-10/20/30Cu alloys in our work. Compared with W-Cu powder precursors synthesized by traditional technologies, the freeze-dried powders (35 nm) are finer and better dispersed, which possess ultrahigh sintering activity. After solid phase sintering, the relative density of prepared W-Cu alloys is as high as above 98%. Meanwhile, the Cu network possesses complete continuity and the W particles keep ultrafine size (178 nm), which is much smaller than W particles in W-Cu literatures. Compared with other traditional technologies, freeze-dried W-Cu alloys in our work possess the highest hardness (499 HV 0.2), taking into account high thermal conductivity (246.9 W/mk) and electrical conductivity (48.3% IACS), which provides a new insight for the further development of W-Cu alloy industries. [Display omitted] [ABSTRACT FROM AUTHOR]