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The use of DSC curves and the Kronmüller theory to study the level of structural defects of Fe-based bulk amorphous alloys

Jeż Bartłomiej, Nabiałek Marcin

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 2

art. no. e144613

EN

This article presents the results of tests carried out on rapid quenched Fe-based alloys. The alloys were made using an injection-casting method. The actual structure of the alloys was also studied using an indirect method, based on H. Kronmüller's theorem. Based on analysis of the primary magnetization curves, in accordance with the aforementioned theory, it was found that Mo causes a change in internal regions associated with changes in the direction of the magnetization vector. The evolution of the thermal properties with increasing volume of Mo has been confirmed by the DSC curves. Addition of Mo, at the expense of the Nb component, results in changes to the crystallization process (i.e. the crystallization onset temperature and number of stages). The study showed that the addition of Mo at the expense of Nb reduces glass forming ability. Based on the DSC analysis, free volumes were determined for the alloys tested. These values were compared with the analysis of primary magnetization curves. It was found that the DSC curves can be used to indirectly describe the structure of amorphous alloys similar to the theory of the approach to ferromagnetic saturation. This approach is new and can be used by many researchers in this field.

2

Flash butt weldability of austenitic high strength steels

Schmidova E., Svanda P., Konecny M.

International Journal of Applied Mechanics and Engineering

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2010

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Vol. 15, no 2

477-482

EN

This paper deals with specific changes in the structure of crossings made of Hadfield's steel, caused by heat and mechanical stress during the welding process, and of rails made of carbon steel. Experiments were undertaken to analyze the sources of damage to the weld joint, established by a post-weld capillary test after machining the weld joints. The analysis demonstrated the presence of welding defects consisting of a phosphide phase and of carbides as a secondary phase. The distribution and amount of this undesirable phase was given by the technical welding parameters employed. It was established that the material is prone to hot tearing only in a very narrow zone inside the heat-affected zone where comprehensive reaustenitization takes place. Initiation of the defects is related to the presence of a phosphide eutectic. A further growth of cracks takes place along the carbide border line; this means that the main factor limiting the use of such welds is attainment of structural degradation. Reducing the thermal effect on the welded components is thus essential for further use of the investigated samples

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Odstranovanie poruch konstrukcii pri zmene unosnosti podlozia budovy

Smutny M., Sedlakova A.

Budownictwo o Zoptymalizowanym Potencjale Energetycznym

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2004

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nr (2)

384--388

EN

The article deals with elimination measurements alternative designs of additional-non-beating constructions defects. There breakdowns were a cause for a status of emergency of some primary school buildings. A measures proposal results from defects origin reasons analysis performed on the in situ detailed survey base. The paper presents exacting decision-making at suitable variant of remedy measures reliable solution choice from the realization sequence and duration at minimal repair costs point of view.