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Al–Si base composites reinforced with different mixtures of Ni and nano-Al 2 O 3 particles have been fabricated by squeeze casting and their metallurgical and mechanical characterization has been investigated. A mixture of Ni and nano-Al 2 O 3 particles of different ratios was added to the melted Al–Si piston alloy at 700 °C and stirred under pressure. After the Al-base-nano-composites were fabricated by squeeze casting, the microstructure and the particle distribution inside the matrix have been investigated using optical and scanning electron microscopes. Moreover, the hardness and the tensile properties of the resulted Al-base-nano-composites were evaluated at room temperature by using Vickers hardness and universal tensile testers, respectively. As a result, in most cases, it was found that the matrix showed a fine eutectic structure of short silicon constituent which appeared in the form of islands in the α-phase around some added particle agglomerations of the nano-composite structures. The tendency of this structure formation increases with the increase of Ni particle addition. As the ratio of the added particles increases, the tendency of these particles to be agglomerated also increases. Regarding the tensile properties of the fabricated Al-base-nano-composites, ultimate tensile strength is increased by adding the Ni and nano-Al 2 O 3 particles up to 10 and 2 wt.%, respectively. Moreover, the ductility of the fabricated composites is significantly improved by increasing the added Ni particles. The composite material reinforced with 5 wt.% Ni and 2 wt.% nano-Al 2 O 3 particles showed superior ultimate tensile strength and good ductility compared with any other added particles in this investigation.

Laser cladding was used to produce surface composite layer reinforced with TiC particles on low-carbon steel alloy for improving the wear and corrosion resistances. The cladding process was carried out at powers of 2800, 2000, 1500, and 1000 W, and a fixed traveling speed of 4 mm/s. The produced layers are free from any cracks. Some of the TiC particles were melted and then re-solidified in the form of fine acicular dendrites. The amount of the melted TiC was increased by increasing the laser power. The hardness of the produced layers was improved by about 19 times of the base metal. Decreasing laser power led to hardness increment at the free surface. The improvement in wear resistance was reached to about 25 times (in case of 1500 W) of the base metal. Moreover, the corrosion resistance shows remarkable improvement after the laser treatment.

YAG fiber laser was used to clad high C–Cr bearing tool steel with VC particles. The cladding process was carried out at laser powers of 1000, 1500, and 2000 W, and a fixed travelling speed of 4 mm/s. Argon gas was used as a shielding during and after laser cladding at flow rate of 15 l/min. VC-surface composite layers consists of VC dendrites/particles dispersed in a matrix of martensite lathes, acicular carbides and some retained austenite were formed through all the laser processing conditions. The depth of the treated zones is in direct proportion to the laser power. On the other hand, the laser power has no great effect on the treated zone width. Some of the VC particles are melted and then re-solidified in the form of fine dendrites during the laser processing. The amount of these melted and re-solidified VC particles were increased by increasing the laser power. The formed composite layers show good metallurgical bonding with the substrate without cracking, except at laser power of 1000 W. The hardness values of the build-up zone in the three different power cases are almost three times as that of the base metal. Decreasing laser power was found to increase the hardness at/near the free surface of treated-zone. The wear resistance of the laser cladded surface was remarkably improved.