In this research, various processing conditions were implemented to enhance the mechanical properties of Al-Si alloys. The silicon content was varied from hypoeutectic (Si-10 wt.%) to eutectic (Si-12.6 wt.%) and hypereutectic (Si-14 wt.%) for the preparation of Al-XSi-3Cu-0.5Fe-0.6 Mg (X = 10–14%) alloys using die casting. Subsequently, these alloys were hot-extruded with an optimum extrusion ratio (17:1) at 400 °C to match the output extruded bar to the compressor size. An analysis of the microstructural features along with a chemical compositional analysis were carried out using scanning electron microscope along with energy dispersive X-ray spectroscopy and transmission electron microscope. The SEM micrographs of the extruded samples displayed cracks in primary Si, and the intermetallic (β-Al5FeSi) phase was fragmented accordingly. In addition, the silicon phase was homogenously distributed, and the size remained constant. The mechanical properties of the extruded samples were enhanced by the increase of silicon content, and consequently the ductility decreased. By implementing proper T6 heat treatment parameters, coherent Al2Cu phases were formed in the Al matrix, and the Si phase was gradually increased along with the silicon content. Therefore, high tensile strength was achieved, reaching values for the Al-XSi-3Cu-0.5Fe-0.6Mg (X = 10–14%) alloys of 366 MPa, 388 MPa, and 420 MPa, respectively.

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In this study, p-type Bi0.5Sb1.5Te3based nanocomposites with addition of different weight percentages of Ga2O3nanoparticles are fabricated by mechanical milling and spark plasma sintering. The fracture surfaces of all Bi0.5Sb1.5Te3nanocomposites exhibited similar grain distribution on the entire fracture surface. The Vickers hardness is improved for the Bi0.5Sb1.5Te3nanocomposites with 6 wt% added Ga2O3due to exhibiting fine microstructure, and dispersion strengthening mechanism. The Seebeck coefficient of Bi0.5Sb1.5Te3nanocomposites are significantly improved owing to the decrease in carrier concentration. The electrical conductivity is decreased rapidly upon the addition of Ga2O3nanoparticle due to increasing carrier scattering at newly formed interfaces. The peak power factor of 3.24 W/mK2is achieved for the base Bi0.5Sb1.5Te3sintered bulk. The Bi0.5Sb1.5Te3nanocomposites show low power factor than base sample due to low electrical conductivity.

In this study, the effects of precompaction on the density, microstructure, mechanical and electrical properties of -Al 2 O 3 bulks fabricated by the combined application of magnetic pulsed compaction (MPC) and a sintering process were reported. The obtained density of the -Al 2 O 3 bulks prepared by the combined processes increased with the increasing MPC pressure and precompaction pressure. The resultant higher hardness and breakdown voltage of the consolidated bulks following combined application of the magnetic pulsed compaction, precompaction and sintering process could be attributed to the homogeneously distributed ultra-fine microstructure than that of general processing, suggesting that the grain growth was remarkably reduced during the MPC processes.

In this research, p‐type Bi2Te3–75% Sb2Te3 thermoelectric alloy powders were produced by gas atomization and subsequently sintered by hot pressing at different temperatures. The grain growth of the hot‐pressed samples was observed with increasing sintering temperature from 380°C to 460°C. The compressive strength increased with increasing hot‐pressing temperature due to the high relative density of bulk samples obtained at high temperatures. The effect of sintering temperature on thermoelectric (TE) properties was studied. The maximum power factor 3.48 mW/mK2 was obtained for the sample hot pressed at 420°C due to the resulting high electrical conductivity and enhanced Seebeck coefficient values.

In this research, effect of the various mechanical milling process on morphology and microstructural changes of nano and micron Al-powders was studied. The milling of Al-powders was performed by both high energy and low energy ball milling process. The influence of milling (pulverizing) energy on the structural changes of Al-powders was studied. Al-nanoparticles were agglomerated during the MA and its size was increased with increasing milling while micron Al-powder gets flattened shape during high energy ball milling due to severe plastic deformation. Meanwhile, structural evolution during high energy ball milling of the nano powder occurred faster than that of the micron powder. A slight shift in the position of X-ray diffraction peaks was observed in nano Al-powders but it was un-altered in macro Al-powders. The variation in lattice parameters was observed only for nano Al powders during the high energy ball milling due to lattice distortion.