To determine the kinetics of ausferrite decomposition in copper-nickel ADI, a kinetic model of Johnson-Mehl-Avrami (JMA), designed for the investigations under non-isothermal conditions, was used. Applying the Netzsch Thermokinetics 3 programme and the method of linear regression, the experimental data obtained by differential scanning calorimetry (DSC) were fitted. The obtained activation energy values were higher than the activation energy of carbon diffusion in austenite and were comprised in the range of 150-240 kJ/mole, depending on the temperature of isothermal transformation, thus showing good agreement with the literature data. In the examined alloys, the influence of copper and nickel on the kinetics is not significant, but with increasing nickel content at low concentrations of copper, the activation energy of the thermal decomposition of ausferrite increases, which indicates an increase in its stability. In terms of the alloying elements impact on the thermal stability of ausferrite, the composition of copper-nickel ADI equal to 0.5 wt. % Cu and 1.5 wt. % Ni seems to be optimal. The obtained results also lead to the conclusion that the simultaneous increase of Cu and Ni content in the copper-nickel cast iron is not intentional.
Keywords: ADI, DSC, kinetics, kinetic equation JMA, ADI, DSC,
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Jarosław Piekło, Stanisław Pysz, Marcin Małysza
Ordered cellular constructions are an important structural element used in armaments, aerospace and automotive industry. The use of Rapid Prototyping technique and control of solidification process allow making castings characterised by such constructions. This article discusses selected issues related with the manufacture of castings of this type and with the mechanical tests and construction of a numerical model to determine the stress/ strain behaviour under the effect of cold work for 50% thickness, using finite element method (FEM).
Keywords: cellular constructions, cast, rapid prototyping, Al-Si alloy, numerical model,
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Katarzyna Kluczwajd, Jacek Krokosz, Rafał Pabiś, Zdzisław Żółkiewicz, Robert Sałat
The characteristics of goldsmith objects included in the collection of Regional Museum in Torun were presented. The results of the chemical composition measurements taken by XRF method on a Niton device on hundreds of historic objects were given and the concluding findings were summarised in a table. An attempt was made to interpret the results of measurements using a „Sammon Mapping" neural network. It was indicated how important these investigations are for museum keepers, extending the range of information about museum objects.
Keywords: chemical composition, NITON device, museum objects,
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