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Determination of γ′+γ / γ Phase Boundary in Ni-Al-Cr System Using DTA Thermal Analysis

Maciąg T., Rzyman K.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 1

237--240

EN

Mechanical properties at elevated temperature, in modern alloys based on intermetallic phase Ni3Al are connected with phase composition, especially with proportion of ordered phase γ′ (L12) and disordered phase γ (A1). In this paper, analysis of one key systems for mentioned alloys - Ni-Al-Cr, is presented. A series of alloys with chemical composition originated from Ni-rich part of Ni-Al-Cr system was prepared. DTA thermal analysis was performed on all samples. Based on shape of obtained curves, characteristic for continuous order-disorder transition, places of course of phase boundaries γ′+γ / γ were determined. Moreover, temperature of melting and freezing of alloys were obtained. Results of DTA analysis concerning phase boundary γ′+γ / γ indicated agreement with results obtained by authors using calorimetric solution method.

2

Phase Diagram of Diblock Copolymer Melt in Dimension d = 5

Dzięcielski M., Lewandowski K., Banaszak M.

Computational Methods in Science and Technology

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2011

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Vol. 17, No. 1-2

17-23

EN

Using the self-consistent field theory (SCFT) in spherical unit cells of various dimensionalities, D, a phase diagram of a diblock, A-b-B, is calculated in 5 dimensional space, d = 5. This is an extension of a previuos work for d = 4. The phase diagram is parameterized by the chain composition, f, and incompatibility between A and B, quantified by the product chi N. We predict 5 stable nanophases: layers, cylinders, 3D spherical cells, 4D spherical cells, and 5D spherical cells. In the strong segregation limit, that is for large chi, the order-order transition compositions are determined by the strong segregation theory (SST) in its simplest form. While the predictions of the SST theory are close to the corresponding SCFT extrapolations for d = 4, the extrapolations for d = 5 significantly differ from them. We find that the S5 nanophase is stable in a narrow strip between the ordered S4 nanophase and the disordered phase. The calculated orderdisorder transition lines depend weakly on d, as expected.

3

Characterization of the structure of FeAl alloy after hot deformation

Jabłońska M., Rodak K., Niewielski G.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 18, nr 1-2

107--110

EN

Purpose: Purpose of this paper was the study of the microstructure of Fe-38Al alloy after hot deformation with the dislocation structure description. Design/methodology/approach: Methodology of the microstructures research included LM (light microscopy) and TEM (transmission electron microscopy) techniques which has characterized the dislocation structure in these materials. The Fe-38Al alloy has been deformed by torsion plastometer within the range of temperatures from 850°C to 1250°C. All samples has been deformed to rupture. Findings: The findings of this study is that the deformation in this alloy is controlled by dislocation motion. The observed dislocations are predominantly of <100> and <111>. At a deformation temperature of 1100°C TEM observations have shown dislocation loops and helices. In this alloy was observed dynamic recrystalization process during the hot deformation. Practical implications: Practical implications of this research is that this alloy may by deformed in long range of strain in temperatures at 800°C to 1000°C Occure 1100°C the plasticity is limited by order - disorder transformation. This transformation could be responsible for dislocations structure behavior what was found. Originality/value: Value of this paper was important in providing a better understanding of technological plasticity of FeAl alloys. The dislocation and reactions between the defects of the structure play a dominant role and are responsible for the variation of technological plasticity.