Papers by Keyword: Solidus Temperature

Abstract: Copper alloys are widely used in mechanical engineering. In the article it is shown that the requirements of consumers to properties of alloys are constantly increasing. Complex alloyed brasses have a high wear resistance and corrosion resistance. The wear resistance is a basic property of an alloy. This characteristic determines the operating life of parts working in the wear conditions. The wear resistance is supported by phase composition of alloy, uniformity of distribution of phase in the structure of alloy, their volume fraction, their morphology and their dimensions. At present time the technology of continuous casting of ingots of alloys Cu59Zn34.6Mn3.5Al2.5Fe0.5Ni0.4, Cu70Zn13Mn7Al5Fe2Si2Pb1, Cu58Zn36Mn2Pb2Si1Al1 and Cu58Zn35Mn3Si1.5Ni1.5Pb1 is developed. However, the need to use new alloys for manufacturing of critical parts requires the development of technology for their production, taking into account the composition of alloy and the features of formation of structure. Therefore, it is necessary to establish well-founded technological parameters of melting and casting of ingots of complex alloyed brass Cu62Zn31.6Mn3Al2Si0.8Ni0.4Cr0.2. For determination of temperatures of phase transformations in the structure of alloy, the differential thermal analysis was carried out. Liquidus and solidus temperatures of alloy were determined. The crystallization range of alloy was established. This brass in a solid state undergoes two phase transformations. The temperature of the first phase transformation is 750 oC. The temperature of the second phase transformation is 515 oC. The obtained experimental data make it possible to describe the proposed mechanism of phase transformations in alloy Cu62Zn31.6Mn3Al2Si0.8Ni0.4Cr0.2 during crystallization and following cooling.

Abstract: A new ternary glass systems of composition xSb₂O₃-(75-x) P₂O₅-25MgO, where x = 30, 40, 50 mol%; has been prepared via melt-quenching method. Synthesized glasses are characterized using XRD, FESEM, EDX, and TG/DTA measurements. The influence of varying Sb₂O₃ concentrations on their thermal properties and crystal structure is evaluated. The XRD patterns confirmed the amorphous nature of samples. SEM images demonstrated interesting phase formation with ribbons-like texture. Three crystalline phases were observed in this glass series which are antimony phosphate, antimony orthophosphate and cervantite. EDX spectra detected the approximate percentage of the raw elemental traces. Thermal analysis of these glasses revealed their high-molecular polymer character for Sb₂O₃ content at 50 mol%. Three different glass transition temperatures are achieved with three different composition each, which are (276, 381, 422 °C) at x=30 mol%, (276, 381, 470 °C) at x=40 mol% and (276, 381, 443 °C) at x=50 mol%. Furthermore, the solidus and liquidus temperature are found to decrease with increasing Sb₂O₃. This observation may open up new research avenues for antimony based ternary glasses.

Abstract: This paper is devoted to the comparison of theoretically defined solidus and liquidus temperatures based on above mentioned theoretical methods with the results of high-temperature thermal analysis carried out on two devices (Netzsch STA 449 F3 Jupiter; Setaram SETSYS 18_TM). On large samples (23 g), the method of direct thermal analysis was applied. On small samples (200 mg), the experiments using differential thermal analysis were realized. It was found out that the solidus and liquidus temperatures for the studied steel grade can vary in dependence on the used determination method. The used methodology of thermal analysis is fully reproducible, and the these thermo-analytical results can be considered as necessary for the correct setting of critical parameters in applied research on the process of steel casting.

Abstract: The paper address the method of assessing the effectiveness of various physical modifying impacts on cast alloys used in mechanical engineering. The method is based on defining the quantity of solid phase calculated by means of the Delphi visual programming language. The study of mechanical properties and microstructure of the alloy AS7p confirmed the results of calculationsIn modern foundry in casting units with required properties the choice of an alloy casting technology and processing of items in a liquid state plays a significant role in machine building.

Abstract: Solidus temperature is one of the important key parameters to describe the non-equilibrium solidification states. However, the study of the non-equilibrium solidus is not enough presently. In present work, the key Influence factors on solidus temperature have been discussed, and it can be calculated by a mathematical model for solute microsegregation during the solidification. The calculated solidus can be agree with the recommended values by some dynamic soft reduction model. It is shown clearly the thermal analysis with non-equilibrium solidus was consistent with the pin shooting experiments. And the effect of the non-equilibrium solidus temperature on solid fraction and the length of soft reduction zone at the solidifying front has been studied sufficiently. Dynamic soft reduction metallurgical effect with the non-equilibrium solidus has been agreed by carbon segregation index and Macroetched experiment.

Abstract: The article focuses on analyzing plastic deformation and microstructure evolution mechanism of foam aluminum material when foam aluminum is compressed and stretched uniaxially at room temperature, and studying plastic deformation of foam aluminum at room temperature and high temperature. Results show that cold forming of foam material is restricted by many factors. So, it only carries out some simple integral forming and local plastic forming; High temperature reduces the yield stress and deformation limits of foam material, that the forming can be easily carried out. If parts of TiH2 foam aluminum are processed, the temperature must be below solidus temperature in order to avoiding destructing pore structure.