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Al 2 O 3-ZrO 2 with a high level of hardness and toughness is known as ceramic steel. Due to its unique properties it can be used as a reinforcement in fabrication of metal matrix composites. In this study, nanoparticles of Al 2 O 3-10% ZrO 2 with an average size of 80 nm were used to fabricate Al matrix composites containing 0.5, 1, 1.5 and 2 wt.% of the reinforcement. The fabrication route was stir casting at 850˚C. There is no report about usage of this reinforcement in fabrication of composites in the literature. The microstructures of the as-cast composites were studied by scanning electron microscope (SEM). Density measurement, hardness and tensile properties were carried out to identify the mechanical properties of the composites. The results revealed that with increasing the reinforcement content, density decreased while yield, ultimate tensile strength and compressive strength increased. Also, hardness increased by increasing the reinforcement content up to 1 wt.% Al 2 O 3-10% ZrO 2 but it decreased in the samples containing higher amounts of reinforcement.

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In this study, deposition of a Ni 3 P nano-scale layer on B 4 C nanoparticles via simple electroless plating in an acidic bath was investigated. B 4 C nanoparticles were produced by mechanical milling with the average size of about 95 nm. Electroless nickel plating was carried out at temperature and pH of 85°C and 5.5, respectively. The uncoated and composite powders were characterized by transition electron microscope and the phases present were revealed by X-ray diffraction. Also, nickel and phosphorous contents of the coating were measured by inductively coupled plasma analysis. The results confirmed deposition of a Ni 3 P layer with the average thickness of about 25 nm on B 4 C nanoparticles. Keywords Electroless plating Á B 4 C nanoparticles Á Ni 3 P nano-scale layer Á Acidic bath Á TEM