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Abstract

Main aim of submitted work is evaluation and experimental verification of inoculation effect on Al alloys hot-tear sensitivity. Submitted work consists of two parts. The first part introduces the reader to the hot tearing in general and provides theoretical analysis of hot tearing phenomenon. The second part describes strontium effect on hot tearing susceptibility, and gives the results on hot tearing for various aluminium alloys. During the test, the effect of alloy chemical composition on hot tearing susceptibility was also analyzed. Two different Al-based alloys were examined. Conclusions deals with effect of strontium on hot tearing susceptibility and confirms that main objective was achieved.
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Abstract

The investigation was carried out on forest soils collected from areas subject to variable pollution. The fraction of strontium was analyzed in soil samples from north-eastern Poland (Borki forest division), treated as a non-polluted region (natural background) and in soil samples from central (Rogów forest division) and south-western Poland (Świerklaniec forest division). The sequential extraction procedure was applied in this study to separate the fractions of strontium. Five fractions were analyzed in every genetic horizon according to the Tessier method. The concentration of strontium was also analyzed in the plants. Both results were compared in order to evaluate the mobility and bioavailability of the trace elements in the environment. The content, distribution and bioavailability of the strontium fractions were investigated with particular emphasis on the contaminated study sites. Total content of strontium in surface horizons depended on the localization. Among analysed fractions strontium, in organic soil horizons, regardless of localization, occurred predominantly in mobile fractions in all examined soils.
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Abstract

This article deal with non-conventional methods to affect the crystallization of Al-alloys by the application of electromagnetic field. The application of electromagnetic field is not technically complicated, it does not require mechanical contact with the melt, and the scale of the crystallization influence is not dependent on the thickness of the casting. Two experimental materials were used: AlSi10MgMn and AlSi8Cu2Mn and two values of electromagnetic induction: B = 0.1 T a B = 0.2 T. The best results for alloy AlSi10MgMn were achieved by application of electromagnetic field with induction B = 0.2 T; during this experiment the best mechanical properties were achieved - the biggest increase of mechanical properties was recorded. The best results for alloy AlSi8Cu2Mn were achieved by combination of electromagnetic field with induction B = 0.1 T and modification by 0.05 wt. % Sr. In this case we don´t recommend to use electromagnetic field with induction B = 0.2 T; because of deposition of coarse grains and decreasing of mechanical properties.
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Abstract

The paper concerns the processes connected with the formation of chromium white cast iron microstructure. The influence of titanium and strontium on the alloy crystallization has been described using TDA method and EDS analysis. Conducted experiments allowed the determination of the selected additions influence on the microstructure of examined alloys. TDA analysis enabled indication of the characteristic temperatures of thermal effects for samples with strontium and titanium and the comparison of results for the reference sample without additions. The results of TDA test also included the analysis of the temperature first derivative values, which presented interesting differences as well. The scanning microscopy observation clearly indicated the difference between the effect of strontium and titanium on the alloy microstructure. The EDS analysis helped to identify the chemical composition of the evolving phases and confirmed the strontium presence in the eutectic. Experimental results allowed to draw reliable conclusions about the effect of applied additions on the crystallization and microstructure of chromium cast iron.
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