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An investigation has been done to study the effect of heat treatment on the formation and distribution of dispersoid particles in two AlMgSi alloys which contained the transition elements such as Zr and Mn, which have a low solubility in the a-aluminium solid solution and thus form dispersoids. The extrapolation technique of CliffLorimer has been used to determine the chemical composition of dispersoid particles. The aim of this investigation was also to compare the effectiveness of Mn and Zr as dispersoid-forming elements in preventing the recrystallization. The incorporation of Si in the metastable Al 3 Zr type of dispersoid particles could increase the nucleation rate by reducing the volume free energy of formation of the dispersoid particles or decreasing the interfacial energy between the precipitate and the matrix. In these alloys, precipitation hardening occurs at higher temperatures than in conventional age-hardening aluminium alloys.

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In this work, we studied the ZnO film thickness effect on the photocatalytic performance of n-ZnO/p-NiO heterostructures. The ZnO and NiO films were prepared by sol-gel dip-coating technique and the thickness of the ZnO film was varied by changing the number of coatingsfrom 2 to12. The formation of the p-NiO/n-ZnO heterostructure was confirmed by X ray diffraction (XRD). The obtained ZnO films present a wurtzite structure with a preferred orientation along (002) direction while the NiO film present a cubic structure highly oriented along (200) direction. UV-visible transmittance spectra of the prepared heterostructures revealed a good transparency in the visible region. The photocatalytic propertiesof the n-ZnO/p-NiO heterostructures were investigated by measuring the degradation rate of methylene blue. All the samples exhibit a good photocatalytic activity under solar light irradiation. The photocatalytic activity of p-NiO/n-ZnO heterostructureswas strongly correlated with the number of ZnO coatings. The highest photocatalytic activity was obtained at 6 coatings with a degradation rate of methylene blue equal to 98.67% for 4.5h of irradiation.