The influence of pouring temperature on the microstructure, fluidity and mechanical properties of ZRE1 magnesium alloy was investigated in this paper. The pouring temperature influences on the fluidity, mean area of grain plane section and mechanical properties. The dependence between pouring temperature and volume fraction of the (Mg,Zn) 12 RE intermetallic phase was not observed. The investigations enabled to determine the optimal pouring temperature of ZRE1 alloy. Moreover, the microstructural stability of ZRE1 alloy during long-term annealing at 150• C, 200• C and 400• C was investigated. ZRE1 magnesium alloy possesses a high microstructural stability up to 200• C, whereas at 400 • C magnesium oxides and rare earth metals oxides are observed in the microstructure.Keywords: Magnesium alloy, ZRE1 alloy, fluidity, microstructure W pracy przedstawiono wyniki badań wpływu temperatury odlewania na mikrostrukturę, lejność i właściwości mechaniczne stopu magnezu ZRE1. Stwierdzono, że temperatura odlewania wpływa na lejność, średnie pole powierzchni płaskiego przekroju ziarna i właściwości mechaniczne stopu ZRE1. Nie zaobserwowano zależności pomiędzy temperaturą odlewania a udziałem objętościowym wydzieleń fazy międzymetalicznej (Mg,Zn) 12 RE. Przeprowadzone badania umożliwiły określenie najkorzystniejszej temperatury odlewania do form piaskowych dla stopu ZRE1. Przeprowadzono także badania stabilności strukturalnej podczas długotrwałego wygrzewania w temperaturze 150• C, 200• C i 400 • C. Stwierdzono, że do temperatury 200• C mikrostruktura jest stabilna, natomiast w temperaturze 400• C stop ZRE1 charakteryzuje się niską stabilnością i skłonnością do tworzenia tlenków magnezu i metali ziem rzadkich.

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The influence of different types of precipitation on the corrosion behavior was investigated in three aluminum-siliconmagnesium alloys. The microstructures of the alloys were studied through optical (OM) and scanning electron microscopy (SEM). The structures consisted of an α-Al solid solution matrix, Si eutectic crystals, secondary phases AlFeSi and AlMgFeSi (Chinese script), as well as Mg2Si. The corrosion behavior was examined with the use of a potentiodynamic polarization test followed by a SEM surface analysis. The results indicate that all the analyzed samples were in the passive state and AlSi10Mg was less reactive in the corrosive environment.

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The researches have concerned cavitation erosion of AlSi7Mg and AlSi11Mg aluminium casting alloys. The alloys have been investigated in the as-cast condition and after the precipitation hardening. The cavitation erosion tests were performed using vibratory cavitation erosion equipment in 5 minutes. Resistance to cavitation of tested materials was estimated by means of MDE (mean depth of erosion) parameter according to ASTM G32. After the cavitation tests eroded surface of the specimens has been observed by means of scanning electron microscopy. The roughness of the surface was measured on profile contact tester. The best resistance for cavitation erosion exhibited AlSi7Mg alloy after heat treatment, the weakest AlSi11Mg alloy in as-cast condition.

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In the present article, the phase identification of four magnesium alloys: Mg-9wt%Al, Mg-8wt%Al-2wt%Ca-0.5wt%Sr, Mg-5wt%Y-4wt%RE and Mg-3wt%Nd-1wt%Gd were studied. The results showed that Mg-9wt%Al alloy contains only the Mg17Al12 intermetallic phase in α-Mg matrix. As-cast microstructure of Mg-8wt%Al-2wt%Ca-0.5wt%Sr alloy consist of α-Mg matrix with (Al,Mg)2Ca and (Al,Mg)4Sr phases. The Mg-5wt%Y-4wt%RE alloy showed several phases. This alloy was characterized by a solid solution structure α-Mg with eutectic α-Mg + Mg14Y2Nd on grain boundaries. The precipitates of MgY, Mg2Y, Mg24Y5 phases have been also observed. The Mg-3wt%Nd-1wt%Gd alloy composed mainly of a solid solution structure α-Mg with eutectic α-Mg + Mg3(Nd,Gd) on the grain boundaries. The regular precipitates of MgGd3 phase have been also observed.