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Study of Si morphology in AlSi21CuNiMg cast alloy using col our and deep etching

Tillová Eva, Chalupová Mária, Kuchariková Lenka, Bonek Mirosław, Uhríčik Milan, Pastierovičová Lucia

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 2

art. no. e144618

EN

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.

2

The Crystallization of the AlSi9 Alloy Designed for the Alfin Processing of Ring Supports in Engine Pistons

Piatkowski J.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 2

65--70

EN

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 α (Al)+Fe+(Si) eutectic containing the α -Al8Fe2Si phase takes place at the end of the crystallization of the double α (Al)+ß(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 α+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.

3

Quality control of cylinder head casting

Tillova E., Chalupova M., Kucharikova L.

Production Engineering Archives

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2017

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Vol. 14

3--6

EN

New challenges for the Aluminium alloys used for the production of castings for automotive engine components result from an evolutionary trend of internal combustion engines towards higher specific power output. Cylinder heads, in particular, have to withstand higher operating temperature and stress levels. Present work describes quality control of microstructure (Si-morphologhy and Si-size) and mechanical properties (UTS, elongation, Brinell hardness) of cylinder head casting as effect of different T6 heat treatment (solution heat treatment time - 2, 3, 4, 5, 6, 7 hours). The data obtained from this study will be used to improve process control, and to help the selection of heat treatment of the casting for future products.

4

The Study of Phase Transformations of AlSi9Cu3 Alloy by DSC Method

Piątkowski J., Przeliorz R., Gontarczyk A.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

109--112

EN

With the use of differential scanning calorimetry (DSC), the characteristic temperatures and enthalpy of phase transformations were defined for commercial AlSi9Cu3 cast alloy (EN AC-46000) that is being used for example for pressurized castings for automotive industry. During the heating with the speed of 10ºC∙min-1 two endothermic effects has been observed. The first appears at the temperature between 495 ºC and 534 ºC, and the other between 555 ºC and 631 ºC. With these reactions the phase transformation enthalpy comes up as +6 J g-1 and +327 J g-1. During the cooling with the same speed, three endothermic reactions were observed at the temperatures between 584 ºC and 471 ºC. The total enthalpy of the transitions is – 348 J g-1. Complimentary to the calorimetric research, the structural tests (SEM and EDX) were conducted on light microscope Reichert and on scanning microscope Hitachi S-4200. As it comes out of that, there are dendrites in the structure of α(Al) solution, as well as the eutectic (β) silicon crystals, and two types of eutectic mixture: double eutectic α(Al)+β(Si) and compound eutectic α+Al2Cu+β.

5

Typical Quality Defects of the „Alphin” Inserts in Engine Pistons

Piątkowski J., Kamiński P.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 2 spec.

65--68

EN

In the dissertation, the 5M Method, is being presented, of typical causes and consequences of quality defects of cast-iron inserts „alphin” embedded in aluminum cast. The diffusive connection of those rings, with pistons casts is being used, because of the extreme conditions in which they need to operate in, which are of high temperature and variable thermo-mechanical burden, which are in the working chamber of combustion engine.