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Cast light metal alloys have retained their importance and unique characteristics as first candidates when cost-function relationship is considered. Hypoeutectic aluminum silicon alloys as (A356) exhibit several specific and interesting properties that qualify them to be used in many automotive and aeronautical applications. Evidence of significant enhancement in strength in the properties of Al-Si cast alloys by incorporating nano-particles have been recently presented. The present study aims at developing nano-dispersed Al-Si alloys with suitable casting methods that assure the dispersion of the nano-particles. In this work a number of cast samples of A356 were prepared by rheo-casting in a specially designed and built furnace unit allowing for the addition of the nano-particles into the molten Al-Si alloy in the semi-solid state with mechanical stirring. The microstructural features and the mechanical properties of the cast and T6 heat treated samples were investigated. The results obtained in this work showed enhancement in the mechanical strength of the nano-dispersed alloys, accompanied by significant increase in the elongation percentage, supported by evidence of refined dendrite arms length, and inter-lamellar spacing.

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In this work a number of cast samples of A356 and A390 were prepared by rheocasting in a specially designed and built furnace unit allowing for the addition of the nano-particles into the molten Al-Si alloy with mechanical stirring. The microstructure features and the mechanical properties of the cast samples were investigated, as well as resistance to wear and corrosion in laboratory tests.The results obtained in this work showed improved wear and corrosion resistance of the nano-dispersed hypereutectic A390 alloys, as well as enhancement in the mechanical strength of the nano-dispersed hypoeutectic A356 alloys, accompanied by significant increase in the elongation percentage, supported by evidence of refined dendrite arms length, and inter-lamellar spacing. The work also shows significant enhancement in the wear and corrosion performance of the nanodispersed alloys.

In this contribution the microstructural changes of four different solution annealed face centered cubic/FCC materials subjected to torsion fatigue were studied. Standard materials X5CrNiMo17‐13‐2 (1.4441, AISI 316 L) and the Co‐base alloy CoCr29Mo6 in addition to two high‐nitrogen stainless steels X13CrMnMoN18‐14‐3 (1.4452) and X6CrNiMnMoN22‐10‐4‐3 were investigated. The torsional fatigue tests were carried out by means of stress controlled incremental step tests at 25 Hz and 3 Hz, respectively. Simultaneously the shear strains were measured in order to gain stress‐strain hysteresis at every 30th cycles. The solution annealed X13CrMnMoN18‐14‐3 (1.4452) and X6CrNiMnMoN22‐10‐4‐3 nitrogen containing steels as well as 316 L‐type stainless steels have been tested and their fatigue endurance limits were determined and compared to that of the CoCr alloy. Transmission electron microscope observations were carried out for the investigated materials before and after the fatigue tests. The results of Transmission electron microscope observations reveal the effect of further nitrogen additions on the fatigue properties. Microstructure observations depicted the effect of nitrogen additions on the modification of slip behavior and the role of the stacking fault energy herein. Wear tests for alloys with substantially more nitrogen than can be accommodated interstitially, form coarse CrN precipitates. These precipitates significantly influence the abrasive wear characteristics of the alloy, particularly when they are large (i. e., 50 μm in width).