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Number of results: 8
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Abstract

The chosen, typical causes of quality defects of cast-iron „alphin” rings embedded in aluminum cast are being presented in this paper.

Diffusive joint of those inserts with the pistons casts is being used, due to extreme work conditions of destructive influence of the fuel mix

and variable thermo-mechanical loads, which reign in the combustion motor working chamber.

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Authors and Affiliations

J. Piątkowski
P. Kamiński
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Abstract

The main goal of the presented work was to determine the relationship between changes in the shape of the derivative curve and the microstructure of Zn-Al-Cu alloys before and after modification. To describe the phenomena that occur in the material during solidification as a result of the modification in the chemical composition, the thermal-derivative analysis method was applied. This method allows to describe and interpret the kinetics of crystallisation of the tested alloys. To describe the morphology and phase composition, light and electron microscopy (SEM, TEM) was also used. The modification of the hypereutectic Zn-Al-Cu alloys with the addition of Ce causes a reduction in the size α' + η eutectics and change in the morphology of the α' phase precipitates from dendritic to “tweed”.

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Authors and Affiliations

M. Krupiński
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Abstract

The effect of possible modification and refining effect of Al-Cu-P-based pre-alloy combined with Fe on the microstructure and the silicon morphology change in hypereutectic Al-Si cast alloy was studied. The samples in the as-cast state were observed by optical and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The 3D morphology of both primary and eutectic silicon was observed by using colour and deep etching in detail. The results showed that the AlCu19P1.4 pre-alloy (1.07 wt.%) combined with the addition of Fe (0.02 wt.%) has a significant effect on the change of the amount, size and morphology of primary Si. This is significantly refined and changes the shape from a coarse irregular star-shaped, polyhedral, or plate-like shape to a fine polyhedral shape. The average size of the primary Si is reduced by about of 78 % from 135 μm to 28 μm and the number of primary Si particles increased from 7.4 to 237. No change in the morphology of the eutectic Si was observed; a refinement of the structure from a coarse needle/plate-like to a fine plate-like structure was seen. The depth etching method using HCl was very effective in the study of the 3D silicon morphology observed, which could be observed in detail without the presence of artefacts.
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Authors and Affiliations

Eva Tillová
1
ORCID: ORCID
Mária Chalupová
1
Lenka Kuchariková
1
ORCID: ORCID
Mirosław Bonek
2
ORCID: ORCID
Milan Uhríčik
1
Lucia Pastierovičová
1

  1. University of Žilina, Faculty of Mechanical Engineering, Department of Materials Engineering, Univerzitná 8215/1, 010 26 Žilina, Slovak Republic
  2. Silesian University of Technology, Faculty of Mechanical Engineering, Department of Engineering Materials and Biomaterials, ul. Konarskiego 18A, 44-100 Gliwice, Poland
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Abstract

In this study, the effects of grain size refiner addition and various pre-heating mold temperatures on AlSi9 cast alloy microstructure and solidification have been evaluated. For different process conditions, thermal analysis was performed for all samples and cooling curves were established. Important parameters in liquidus and eutectic Si-phase regions have been calculated using the first derivative cooling curves. Secondary Dendrite Arm Spacing (SDAS) variation was also determined. Experimental results question the effectiveness of cooling curve parameters in providing the microstructure data as a function of refinement. The present work shows that the effect of grain refiner addition on the value of SDAS was higher when the solidification time was lower. It indicated that the solidification parameters such as nucleation temperatures of α-Al phase, undercooling temperature and total solidification time were affected by grain refinement. It has been found that the addition of grain refiner affect the eutectic phase formation time. However, it has no effect on the eutectic phase morphology.

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Authors and Affiliations

Badiâ Ait El Haj
Aboubakr Bouayad
Mohammed Alami
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Abstract

This article presents a study of the crystallization and microstructure of the AlSi9 alloy (EN AC-AlSi9) used for the alfin processing of iron ring supports in castings of silumin pistons. Alfin processing in brief is based on submerging an iron casting in an Al-Si bath, maintaining it there for a defined time period, placing it in a chill mould casting machine and immersing it in the alloy. This technology is used for iron ring supports in the pistons of internal combustion engines, among others. Thermal analysis shows that when the AlSi9 alloy contains a minimal content of iron, nucleation and increase in the triple (Al)+Fe+(Si) eutectic containing the -Al8Fe2Si phase takes place at the end of the crystallization of the double (Al)+(Si) eutectic. Due to the morphology of the ”Chinese script” the -Al8Fe2Si phase is beneficial and does not reduce the alloy’s brittleness. After approx. 5 hours of alfin processing, the -Al5FeSi phase crystallizes as a component of the +Al5FeSi+(Si) eutectic. Its disadvantageous morphology is ”platelike” with sharp corners, and in a microsection of the surface, ”needles” with pointed corners are visible, with increases the fragility of the AlSi9 alloys.

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Authors and Affiliations

J. Piątkowski
ORCID: ORCID
M. Czerepak
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Abstract

In order to identify the influence of different Mn, Cd, V and Zr content on the properties of Al-Cu casting alloys in hydraulic valves, orthogonal test methods were used to prepare alloy test bars with different elements and contents. Tensile tests were performed on the test bars so obtained. The microstructure of alloys with different compositions is studied. The results show that adding approximately 0.4% of Mn can not only form a strengthening phase but also reduce the excessive segregation of the matrix along the grain boundary. A Cd content of 0.2% can promote the formation of micro Cd spheres in the softer aluminum matrix. Hard spots increase the wear resistance of the material; however, an excess of Cd will cause element segregation and deteriorate the mechanical properties of the valve body. Zr and V refine the grains in the alloy; however, an excess of these elements will lead to a large area of segregation. If proper heat treatment is lacking, the mechanical properties of the valve body deteriorate.

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Authors and Affiliations

Rong Li
ORCID: ORCID
Lunjun Chen
Qi. Zeng
ORCID: ORCID
Ming Su
Zhiping Xie
ORCID: ORCID
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Abstract

Recycling of aluminium returnable material through its reuse is now an essential component of the production of aluminium alloy castings. The main goal is to find a suitable ratio of the primary alloy and the returnable material in the batch, thus determining the right compromise between the price and the quality of the casting. Experimental alloys were evaluated by thermal analysis, combination of structural analytical techniques and selected mechanical properties. The alloys were also subjected to tearing susceptibility testing. The increase in the returnable material amount resulted in changes in the alloy properties at the first increase in volume to 20%. After exceeding the balanced ratio (50:50), there was considerable degradation of the microstructure, failure to achieve the minimum values of some mechanical properties required by the standard, and the alloy showed increased susceptibility to tearing.

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Authors and Affiliations

M. Matejka
ORCID: ORCID
D. Bolibruchová
ORCID: ORCID
M. Chalupová
ORCID: ORCID
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Abstract

The article will be focused on analysis of properties of aluminum alloy for the casting of type Al-Mg. As an experimental material was used aluminum alloy EN AC 51200, supplied in a cast state without a heat treatment. It was produced by the continuous casting method. Experiments deal with microstructural material analysis, fractographic analysis, mechanical and fatigue tests. The microstructure of the testing sample was examined using an optical microscope Neophot 32. Fatigue properties of aluminum alloy was tested by three-point bending cyclic loading. The fracture surface of the testing sample was examined using scanning electron microscopy (SEM), where sample was observed on various stages of the fatigue process, its characteristics and differences of fracture surfaces.

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Authors and Affiliations

M. Uhríčik
ORCID: ORCID
P. Palček
M. Chalupová
ORCID: ORCID
P. Hanusová
L. Kuchariková
ORCID: ORCID

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