Hydrogen production via high high-temperature steam electrolysis consumes less electrical energy than compared to conventional low low-temperature water electrolysis, mainly due to the improved thermodynamics and kinetics at elevated temperaturetemperatures. The elementalElemental powders of Cu, Ni, and YSZ are were used to synthesize high high-temperature electrolysis cathodecathodes, of Ni/YSZ and Cu/YSZ composites, by mechanical alloying. The metallic particles of the composites were uniformly covered with finer YSZ particles. Sub-micron sized pores are were homogeneously dispersed in the Ni/YSZ and Cu/YSZ composites. In this study, The cathode materials were synthesized and their Characterizations properties were evaluated in this study: It was found that the better electric conductivity of the Cu/YSZ composite was measured improved compared tothan that of the Ni/YSZ composite. Slight A slight increase in the resistance can be produced for in a Cu/YSZ cathode by oxidation, but it this is compensated offset for by a favorable thermal expansion coefficient. Therefore, Cu/YSZ cermet can be adequately used as a suitable cathode material of in high high-temperature electrolysis.

High-energy mechanical milling (HEMM) and sintering into Al-Mg alloy melt were employed tofabricate an Al alloy matrix composite reinforced with submicron and micron sized Al2O3 particles. Al-basedmetal matrix composite (MMC) reinforced with submicron and micron sized Al2O3 particles was successfullyfabricated by sintering at 1000oC for 2h into Al-Mg alloy melt, which used high energy mechanical milled Al-SiO2-CuO-ZnO composite powders. Submicron/micron-sized Al2O3 particles and eutectic Si were formed by in situdisplacement reaction between Al, SiO2, CuO, and ZnO during sintering for 2h into Al-Mg alloy melt and werehomogeneously distributed in the Al-Si-(Zn, Cu) matrix. The refined grains and homogeneously distributedsubmicron/micron-sized Al2O3 particles had good interfacial adhesive, which gives good wear resistance withhigher hardness.

Thermally evaporated 10 nm-Ni/1 nm-Au/(30 nm-poly)Si structures were fabricated in order to investigate the thermal stability of Au-inserted nickel silicide. The silicide samples underwent rapid thermal annealing at 300~1100˚C for 40 seconds. The sheet resistance was measured using a four-point probe. A scanning electron microscope and a transmission electron microscope were used to determine the cross-sectional structure and surface image. High-resolution X-ray diffraction and a scanning probe microscope were employed for the phase and surface roughness. According to sheet resistance and XRD analyses, nickel silicide with Au had no effect on widening the NiSi stabilization temperature region. Au-inserted nickel silicide on a single crystal silicon substrate showed nano-dots due to the preferred growth and a self-arranged agglomerate nano phase due to agglomeration. It was possible to tune the characteristic size of the agglomerate phase with silicidation temperatures. The nano-thick Au-insertion was shown to lead to self-arranged microstructures of nickel silicide.

Al-42wt%Nb powder was prepared by high-energy mechanical milling(HEMM). The particle size, phase transformation and microstructure of the as-milled powder were investigated by particle size distribution (PSD) analyzer, scanning electron microscopy (SEM), X-ray diffractometery (XRD), transmission electron microscopy (TEM)and differential thermal analysis (DTA). The milled powders were heated to a sintering temperature at 1000C with under vaccum with vaccum tube furnace. Microstructural examination of sintered Ti-42wt%Nb alloy using 4h-milled powder showed Ti-rich phases (α-Ti) which are fine and homogeneously distributed in the matrix (Nb-rich phase: β-Ti). The sintered Ti-42wt%Nb alloy with milled powder showed higher hardness. The microstructure of the as quenched specimens fabricated by sintering using mixed and milled powder almost are same, but the hardness of as quenched specimen fabricated by using mixed powder increased due to solution hardening of Nb in Ti matrix. The aging effect of these specimens on microstructural change and hardening is not prominent.

The microstructure and hardness of (W,Ti)C cemented carbides with a different metallic binder composition of Ni and Co fabricated by powder technology were investigated. The densifications of the prepared materials were accomplished by using vacuum sintering at . Nearly full dense (W,Ti)C cemented carbides were obtained with a relative density of up to 99.7% with 30 wt.% Co and 99.9% with 30 wt.% Ni as a metallic binder. The average grain size of the (W,Ti)C-Co and the (W,Ti)C-Ni was decreased by increasing the metallic binder content. The hardness of the dense (W,Ti)C-15 wt%Co and (W,Ti)C-15 wt%Ni, was greater than that of the other related cemented carbides; in addition, the cobalt-based cemented carbides had greater hardness values than the nickel-based cemented carbides.

The microstructural and mechanical properties of Al-Si alloyed powder, prepared by gas atomization fallowed by hot extrusion, were studied by optical and scanning electron microscopies, hardness and wear testing. The gas atomized Al-Si alloy powder exhibited uniformly dispersed Si particles with particle size ranging from 5 to . The hot extruded Al-Si alloy shows the average Si particle size of less than . After heat-treatment, the average particle size was increased from 2 to . Also, mechanical properties of extruded Al-Si alloy powder were analyzed before and after heat-treatment. As expected from the microstructural analysis, the heat-treated samples resulted in a decrease in the hardness and wear resistance due to Si particle growth. The friction coefficient of heat-treated Al-Si alloyed powder showed higher value tough all sliding speed. This behavior would be due to abrasive wear mechanism. As sliding speed increases, friction coefficient and depth and width of wear track increase. No significant changes occurred in the wear track shape with increased sliding speed.

The microstructure and mechanical properties of hot-pressed composites with a different sintering temperature have been studied. The size of matrix grain and Cu dispersion in composites increased with increase in sintering temperature. Fracture toughness of the composite sintered at high temperature exhibited an enhanced value. The toughness increase was explained by the thermal residual stress, crack bridging and crack branching by the formation of microcrack. The nanocomposite, hot-pressed at , showed the maximum fracture strength of 707 MPa. The strengthening was mainly attributed to the refinement of matrix grains and the increased toughness.

Lanthanum oxide was introduced to molybdenum powder by liquid-liquid doping and liquid-solid doping respectively. Mo alloys were prepared by powder metallurgy technology. The size distribution and feature of dopant particles and the fractographs of Mo alloys were investigated by TEM and SEM respectively. The results indicated that liquid-liquid doping method is favorable for refining and dispersing particles uniformly in matrix. Fracture toughness of Mo alloys prepared by liquid-liquid doping showed better results than that of liquid-solid doping. Furthermore, the influences of the size distribution of on properties of Mo alloys was discussed by dislocation pile-up theory.

The type, volume fraction, size, shape and arrangement of embedded particles influence the mechanical properties of the particle reinforced metal matrix composites. This presents the investigation of the SiC particle and porosity distributions in various aluminum matrix composites produced by cold- and hot-pressing. The microstructures were characterized by optical microscopy and stereological parameters. SiC and porosity volume fractions, and the anisotropy distribution function were measured to establish the influence of the consolidation method.