Thermoelectric materials Mg2Si0.8Sn0.2 were sintered under three different conditions including no electricity sintering(NCS), low electricity sintering(LCS),and high electricity sintering(HCS). Thermoelectric performance and microstructure of three group samples were measured and compared. The results indicate that the application of electric current during the sintering process changes the microstructure and significantly increases the density of samples, and increases the electric conductivity and the power factor. The electric current activated/assisted sintering is an effective way to obtain thermoelectric materials with excellent performance.
Mechanical alloying (MA) and field-activated, pressure-assisted synthesis (FAPAS) were used for the in situ synthesis and densification of ultra-hard, super-abrasive AlMgB14 metallic ceramic, performed at 1500℃ under a pressure of 60 MPa with the elemental constituents of aluminum, magnesium, and boron. The microstructure and components of synthesized metallic ceramic were observed and determined by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the main components of the samples were AlMgB14 with a few MgAl2O4·MgAl2O4 was derived from the contamination of the preliminary powders and the milling process. The average hardness of the samples that provided the results was 26.1 GPa. The average density of the samples was 2.62 g/cm-3 , which is 98% of its theoretical density. The sample of AlMgB14-TiB2 composite with 30 wt% TiB2 had a hardness of 29.5 GPa, which is consistent with that of AlMgB14-TiB2 composite with 30 wt% TiB2 prepared by mechanical alloying/hot uniaxial pressing. Thus, a new approach was developed using the mechanical alloying and FAPAS process to synthesize AlMgB14 with fast heating, high efficiency, energy saving, and high yield.
