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1

Crystallization Behavior and Properties of Hypereutectic Al-Si Alloys with Different Iron Content

Deev V., Prusov E., Prikhodko O., Ri E., Kutsenko A., Smetanyuk S.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 4

101--107

EN

Understanding the influence of iron impurity on the formation of the structure and the properties of hypereutectic aluminum-silicon alloys are important for achieving the required quality of castings, especially those obtained from secondary materials. In the present work, the influence of different iron contents (0.3, 1.1, and 2.0 wt.%) on the crystallization process, microstructure and mechanical properties of the Al-15% Si alloy was studied. It is shown that the presence of iron impurity in the Al-15% Si alloy leads to increasing the eutectic crystallization time from 6.2 to 7.6 s at increasing the iron content from 0.3 wt.% to 1.1 wt.%, changing the structure of the alloy eutectic in the solid state. The primary silicon and β-Al5SiFe phase coexist in the structure of the Al-15% Si alloys at a temperature below 575°C in the range of iron concentrations from 0 to 2 wt.% in equilibrium conditions. In the experimental alloys structure, the primary crystals of the β-phase were metallographically detected only in the alloys containing 1.1 and 2 wt.% of iron impurity. Increase of the iron content up to 2 wt.% significantly reduces the mechanical properties of the Al-15% Si alloy due to the formation of large platelet-like inclusions of β-Al5SiFe phase.

2

In-situ formed, ultrafine Al-Si composite materials: ductility

Guba P., Gesing A., Sokolowski J., Conle A., Sobiesiak A., Das S., Kasprzak M.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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Vol. 92, nr 1-2

5--12

EN

Purpose: The work objective includes optimization of the casting production and heat treatment processes that will simultaneously maximize the combination of strength, hardness, and ductility for hypereutectic Al-Si compositions with Si volume fractions of as much as 25 vol.%. In addition, such an in-situ formed composite alloy will attain a unique combination of low production cost, high potential recycled content, and functional characteristics suitable for mission critical aerospace and vehicular applications. Design/methodology/approach: The unique High Pressure Die Casting Universal Metallurgical Simulator and Analyser (HPDC UMSA) was used for melting, cyclic melt treatment, and solidification of the hypereutectic Al-Si-X (A390). The produced as-cast structures contained colonies of nano-diameter Si whiskers and other morphologies, and absence of primary silicon particles. Heat treated structures rendered nano and ultrafine metal matrix composites. Findings: New developed as-cast Al-Si materials containing nano-diameter Si whiskers, without primary silicon particles required ultra short time heat treatment to result in nano and ultrafine metal matrix composite, rendering their hardness, strength and wear resistance, and the same time retaining toughness and ductility. Research limitations/implications: The cast samples were produced in laboratory conditions and potential tensile strength was estimated from empirical correlation with micro-hardness measurements. In the future, the comprehensive mechanical properties need to be tested. Practical implications: These ultrafine Si, Al-MMCs can be net-shape formed by modified HPDC technology or consolidated from spray-atomized alloy powder. Originality/value: Optimization of the entire production process for the hypereutectic Al-Si alloy compositions achieved a uniform distribution of ~ 25 vol.% of ultrafine Si particles in ductile FCC-Al matrix further reinforced by age hardening with nano-scale spinodal GP-zones. The associated mechanical property and ductility improvements will open a wide range of critical lightweighting components in transportation: aerospace, terrestrial vehicle and marine to the optimized hypereutectic Al-Si alloys. Presently, these components do not use the commercial HPDC A390 alloys due to their limited ductility and strength. Proposed new technology will allow conversion of various cast airspace alloys with ultrahigh mechanical properties to the automotive applications.

3

Investigations of linear contraction and shrinkage stresses development in hypereutectic al-si binary alloys

Mutwil J., Kujawa K., Bajon G., Hajn P.

Archives of Foundry Engineering

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2009

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Vol. 9, iss. 4

157-164

EN

Shrinkage phenomena during solidification and cooling of hypereutectic aluminium-silicon alloys (AlSi18, AlSi21) have been examined. A vertical shrinkage rod casting with circular cross-section (constant or fixed: tapered) has been used as a test sample. Two type of experiments have been conducted: 1) on development of the test sample linear dimension changes (linear expansion/contraction), 2) on development of shrinkage stresses in the test sample. By the linear contraction experiments the linear dimension changes of the test sample and the metal test mould as well a temperature in six points of the test sample have been registered. By shrinkage stresses examination a shrinkage tension force and linear dimension changes of the test sample as well a temperature in three points of the test sample have been registered. Registered time dependences of the test bar and the test mould linear dimension changes have shown, that so-called pre-shrinkage extension has been mainly by mould thermal extension caused. The investigation results have shown that both: the linear contraction as well as the shrinkage stresses development are evident dependent on metal temperature in a warmest region the sample (thermal centre).

4

Kształtowanie struktury na przekroju odlewu z silnie nadeutektycznego stopu Al-Si (Al-30%Si)

Orłowicz A. W., Mróz M.

Archiwum Odlewnictwa

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2006

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R. 6, nr 21/2

303--310

PL

Praca dotyczy doboru składu chemicznego i kształtowania mikrostruktury, a w szczegolności wielkości wydzieleń pierwotnych krzemu w siluminie nadeutektycznym, celem poprawy odporności na zużycie ścierne. Zastosowano stop Al-30%Si zawierający dodatki stopowe (Ni, V, Cr). Poprzez zmianę szybkości chłodzenia uzyskano wydzielenia krzemu o maksymalnej długości od 25 žm do 71,4 žm. Uszlachetnianie powierzchniowe odlewu plazmą łuku elektrycznego pozwoliło uzyskać wielkość wydzieleń krzemu pierwotnego o maksymalnej długości 10 žm.

EN

Selection of chemical composition and microstructure shaping are discussed, in particular the size of primary silicon precipitates in hypereutectic silicon in order to improve the resistance to wear of cast combustion-engine elements. The applied alloy, Al-30%Si, contains alloying additives (Ni, V, Cr). The primary silicon precipitates of maximum length from 25.0 žm to 71.4 žm were obtained through cooling rate variation. Surface refinement of castings with electric arc plasma permitted obtaining of primary silicon precipitates of maximum length 10 žm.

5

Powierzchniowa obróbka siluminów skupionym źródłem ciepła

Lipiński T.

Archiwum Odlewnictwa

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2004

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R. 4, nr 11/1

293--298

PL

W pracy przedstawiono wyniki badań rozkładu twardości siluminu podeutektycznego AK7, okołoeutektycznego AK 12 i nadeutektycznego AK20 po obróbce metoda spawalniczą TIG. Przedstawiono wysoką skuteczność metody dla rozdrobnienia fazy &alpha i eutektyki (&alpha+&beta) oraz jej ograniczony wpływ na rozdrobnienie pierwotnej fazy &beta w nadeutektycznych stopach Al-Si.

EN

This work presents results distribution microhardness and microstructure of silumin AK7, AK12 and AK20 after treatment by means of weld's method TIG. Show a gain of fine-grained &alpha phase and (&alpha+&beta) eutectic phase after treatment by TIC method and limited of influence the method on modification of primary &beta phase in hypereutectic alloys Al-Si.

6

Obliczanie namiaru wsadu metalowego z wykorzystaniem algorytmu simpleks

Piątkowski J., Szymszal J., Binczyk F.

Archiwum Odlewnictwa

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2002

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R. 2, nr 6

179-188

PL

Uniwersalną metodą rozwiązywania zagadnień optymalizacyjnych z zastosowaniem programowania liniowego jest algorytm simpleks. Jest to nowoczesny sposób badań operacyjnych, polegający na poszukiwaniu kolejnych rozwiązań bazowych programowania liniowego w postaci kanonicznej. W pracy przedstawiono metodę wyznaczania namiaru wsadu metalowego opartą o optymalizację simpleks, pozwalającą na określenie położenia ekstremum funkcji wieIu zmiennych. Obliczenia prowadzono na przykladzie nadeutektycznego siluminu AISi17 z dodatkiem Cu, Ni i Mg.

EN

Simplex algorithm is universal method of dissolving of questions optimisation with utilization of linear programmes. It is this modern way of operating investigations, depending on search of next base solutions of linear programme in canonical form. In work metal leaning of marking of bearing of batch method was introduced about optimisation simplex, permitting onto qualification of position of extreme variable function. Calculation hypereutectic AISi17 alloy with addition Cu, Ni and Mg alloys was led on example.

7

Relationship of structure and properties of Al-Si alloys.

Taran Yu.N., Kutsova V.Z., Uzlov K.I.

Inżynieria Materiałowa

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1998

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R. XIX, nr 3

588-591

EN

The aim of the present investigation had to be study of combined influence of copper and phosphorous on the structure and properties of hypereutectic Al-Si alloys. In the structure of investigated alloys it could be possible to fix together with aluminium and silicon solid solutions intermetallic phases contained Cu, P, Fe. Alloys modified with phosphorous and copper have average tensile strength higher than syntetic binary ones. At the same time elongation dropping down. In the frame of the present investigation the effect of copper and phosphorous on eutectic and peritectic transformations in Al-Si system has been studied.

8

Phase transitions and structure of hypereutectic Al-Si alloys.

Taran Yu.N., Kutsova V.Z., Uzlov K.I., Evsyukova I.M.

Inżynieria Materiałowa

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1998

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R. XIX, nr 3

584-587

EN

Regularities of structural and pase transitions in hypereutectic Al-Si alloys have been studied. Peritectic (740-680 degrees centigrade) and allotropic transformations (680 degrees centigrade) has been found in studied alloys. On the base of experimental data mechanism of peritectic reaction in hypereutectic Al-Si alloys has been proposed.

9

Formability modelling of aluminium base PM alloys.

Bagaviev A., Durisin J., Dybiec H., Klein K., Mandziej S., Ziaja G.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1153-1158

EN

The paper presents the results investigations carried out in the frame of the Project CT 96-0750 MicroAlu of Inco-Copernicus program. The investigated materials are PM aluminium alloys with high contents of silicon. The aim of this part is a comprehensive characterisation of microstructure features and specific parameters at the example of an AlSi27Ni6 alloy. The experiments on the plastic and viscoplastic behaviour of this alloy (compressive and tensile tests) at different temperatures and strain rates were done to identify the material properties. The evolution of the microstructure of the tested specimens due to temperature rise and deformation process was investigated with optical and electron microscopy as well as with X-ray analysis technique. The alloy was compacted by a PM extrusion process to a preform and then forged to a final product -connecting rod. From the performed experiments the constitutive parameters were identified and the connecting rod forging process has been simulated by means of a general purpose FEM program.