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1

Microscopic Analysis of Layers Containing Mg2Si and Mg17Al12 Phases Fabricated on AZ91 Through Thermochemical Treatment

Mola R., Cieślik M.

Archives of Foundry Engineering

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2019

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iss. 3

119--124

EN

The thermochemical treatment applied to improve the surface properties of AZ91 consisted in heating the material in contact with AlSi10Mg powder at 445 oC for 30 min. During heat treatment process the powder was held under pressure to facilitate the diffusion of the alloying elements to the substrate and, accordingly, the formation of a modified layer. Two pressures, 1 MPa and 5 MPa, were tested. The resultant layers, containing hard Mg2Si and Mg17Al12 phases, were examined using an optical microscope and a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer (EDS). The experimental data show that the layer microstructure was dependent on the pressure applied. A thicker, three-zone layer (about 200 μm) was obtained at 1 MPa. At the top, there were Mg2Si phase particles distributed over the Mg17Al12 intermetallic phase matrix. The next zone was a eutectic (Mg17Al12 and a solid solution of Al in Mg) with Mg2Si phase particles embedded in it. Finally, the area closest to the AZ91 substrate was a eutectic not including the Mg2Si phase particles. By contrast, the layer produced at a pressure of 5 MPa had lower thickness of approx. 150 μm and a two-zone structure. Mg2Si phase particles were present in both zones. In the upper zone, Mg2Si phase particles were regularly distributed over the Mg17Al12 intermetallic phase matrix. The lower zone, adjacent to the AZ91, was characterized by a higher volume fraction of Mg2Si phase particles distributed over the matrix composed mainly of Mg17Al12. The alloyed layers enriched with Al and Si had much higher hardness than the AZ91 substrate.

2

Analiza struktury złącza PA38/AZ31 wytworzonego metodą zgrzewania dyfuzyjnego

Mola R., Cieślik M., Bartos J.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2018

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z. 90 [298], nr 3

367--376

PL

W artykule przedstawiono analizę struktury złącza stop aluminium (PA38)–stop magnezu (AZ31) wytworzonego metodą zgrzewania dyfuzyjnego. Za pomocą mikroskopu optycznego i elektronowego mikroskopu skaningowego przeprowadzono szczegółowe badania metalograficzne. Skład chemiczny strefy złącza określono metodą mikroanalizy rentgenowskiej (EDS). Wykonano również pomiary mikrotwardości metodą Vickersa łączonych materiałów i strefy złącza. W wyniku procesu zgrzewania uzyskano trwałe połączenie. Strefa złącza, o grubości ok. 50 µm, miała budowę dwuwarstwową. Od strony stopu PA38 w złączu zidentyfikowano grubszą warstwę (ok. 40 µm) fazy międzymetalicznej Al3Mg2, od strony stopu AZ31 cieńszą warstwę (ok. 10 µm) fazy międzymetalicznej Mg17Al12. W mikrostrukturze strefy złącza od strony stopu PA38 na tle osnowy fazy Al3Mg2 stwierdzono obecność drobnych cząstek fazy Mg2Si. Od strony stopu AZ31, na tle fazy Mg17Al12, obserwowano lokalnie iglaste cząstki fazy Al-Mn-Si. Na podstawie pomiarów mikrotwardości stwierdzono, że strefa złącza zbudowana głównie z faz międzymetalicznych Mg-Al charakteryzuje się kilkukrotnie wyższą mikrotwardością w porównaniu z łączonymi stopami.

EN

This paper presents the results of the microstructure investigation of the aluminium alloy (PA38) – magnesium alloy (AZ31) joint fabricated by diffusion bonding. The structure of the bonding zone was examined using optical microscopy and scanning electron microscopy. The chemical composition of the bonding zone was determined by energy dispersive X-ray microanalysis. The microhardness measurements of the alloys and the bonding zone was also conducted. As a result of the diffusion bonding process the alloys were joined together. The bonding zone with a thickness of about 50μm had two-layer structure. In the bonding zone the thicker layer (about 40μm) of Al3Mg2 intermetallic phase was observed on the PA38 alloy side. The thinner layer (about 10 μm) of Mg17Al12 intermetallic phase was observed on the AZ31 alloy side. In the area of the bonding zone close to the PA38 alloy fine particles of Mg2Si phase were found in the matrix of Al3Mg2. In the bonding zone close to the AZ31 alloy locally a needle-shaped particles of the Al-Mn-Si phase were observed over the Mg17Al12 phase matrix. The results of microhardness measurement revealed that the bonding zone composed mainly of Mg-Al intermetallic phases layers had much higher microhardness than the joined alloys.

3

Wykorzystanie metody akumulacyjnego walcowania pakietowego do wytwarzania lekkich wielowarstwowych materiałów Al-Mg-Al

Wierzba A., Mróz S., Szota P., Stefanik A., Mola R.

Rudy i Metale Nieżelazne Recykling

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2018

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R. 63, nr 5

11--17

PL

W pracy zaproponowano wykonanie lekkiego materiału wielowarstwowego składającego się z trzech warstw, w którym zewnętrzne warstwy stanowiło aluminium w gatunku 1050A, natomiast środkowa warstwa wykonana była ze stopu AZ31. Przygotowany materiał wielowarstwowy poddano odkształceniu za pomocą metody ARB w 4 przepustach przy temperaturze 400°C. Przyjęto, że początkowa grubość pakietu wynosiła 3 mm (po 1 mm dla każdego komponentu). Walcowanie zrealizowano w walcarce laboratoryjnej duo D150 z zastosowaniem symetrii i asymetrii prędkości obrotowych walców. W pracy wykazano, że wprowadzenie asymetrii do metody ARB dla badanego materiału Al-Mg-Al, wpływa na rozdrobnienie struktury w porównaniu do procesu symetrycznego.

EN

The study has proposed the production of a lightweight multilayered material composed of three layers, in which the external layers is made up by aluminium in grade 1050A, while the central layer is made of the alloy AZ31. The prepared multilayered material was subjected to deformation by the ARB method in 4 rolling passes. The initial packet thickness was assumed to be 3 mm (1 mm for each component), and the rolling process was conducted at a temperature of 400°C. The rolling was carried out on a D150 laboratory two-high mill equipped with individual working roll drives, which enabled a rotational roll speed asymmetry to be introduced into the rolling process. As a result of the rolling carried out, a multilayered material was obtained, which was characterized by a refined structure.

4

The Microstructure and Properties of the Bimetallic AZ91/AlSi17 Joint Produced by Compound Casting

Mola R., Bucki T.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

71--76

EN

Bimetallic AZ91/AlSi17 samples were produced by compound casting. The casting process involved pouring the AZ91 magnesium alloy heated to 650ºC onto a solid AlSi17 aluminum alloy insert placed in a steel mould. Prior to casting, the mould with the insert inside was heated to about 370ºC. The bonding zone formed between AZ91 and AlSi17 had a thickness of about 200 μm; it was characterized by a non-homogeneous microstructure. Two different areas were distinguished in this zone: the area adjacent to the AZ91 and the area close to the AlSi17. In the area closest to the AZ91 alloy, a eutectic composed of an Mg17Al12 intermetallic phase and a solid solution of Al in Mg was observed. In bonding zone at a certain distance from the AZ91 alloy an Mg2Si phase co-occurred with the eutectic. In the area adjacent to the AlSi17 alloy, the structure consisted of Al3Mg2, Mg17Al12 and Mg2Si. The fine Mg2Si phase particles were distributed over the entire Mg-Al intermetallic phase matrix. The microhardness of the bonding zone was much higher than those of the materials joined; the microhardness values were in the range 203-298 HV. The shear strength of the AZ91/AlSi17 joint varied from 32.5 to 36 MPa.

5

Characterization of the Bonding Zone in a ZE41/AlSi12 Joint Fabricated by Liquid- Solid Compound Casting

Mola R., Bucki T.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 2

203--208

EN

The study involved using the liquid-solid compound casting process to fabricate a lightweight ZE41/AlSi12 bimetallic material. ZE41 melt heated to 660 °C was poured onto a solid AlSi12 insert placed in a steel mold. The mold with the insert inside was preheated to 300 °C. The microstructure of the bonding zone between the alloys was examined using optical microscopy and scanning electron microscopy. The chemical composition was determined through linear and point analyses with an energy-dispersive X-ray spectroscope (EDS). The bonding zone between the magnesium and aluminum alloys was about 250 μm thick. The results indicate that the microstructure of the bonding zone changes throughout its thickness. The structural constituents of the bonding zone are: a thin layer of a solid solution of Al and Zn in Mg and particles of Mg-Zn-RE intermetallic phases (adjacent to the ZE41 alloy), a eutectic region (Mg17(Al,Zn)12 intermetallic phase and a solid solution of Al and Zn in Mg), a thin region containing fine, white particles, probably Al-RE intermetallic phases, a region with Mg2Si particles distributed over the eutectic matrix, and a region with Mg2Si particles distributed over the Mg-Al intermetallic phases matrix (adjacent to the AlSi12 alloy). The microstructural analysis performed in the length direction reveals that, for the process parameters tested, the bonding zone forming between the alloys was continuous. Low porosity was observed locally near the ZE41 alloy. The shear strength of the AZ91/AlSi17 joint varied from 51.3 to 56.1 MPa.

6

Effects of the process parameters on the formability of the intermetallic zone in two-layer Mg/Al materials

Mola R., Mroz S., Szota P.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 4

1401--1409

EN

This paper discusses experimental results concerning the plastic deformation of the bonding zone in a two-layer AZ31/Al material subjected to compression loads. The specimens were fabricated by diffusion bonding method. The 50 μm thick transition zone at the AZ31/Al interface contained Mg–Al intermetallic phases. The physical modelling of the deformation behaviour of the intermetallic zone was performed using a Gleeble 3800 system. The compression tests were carried out at two temperatures (300 and 400 °C), two strain rates (0.1 and 1.0 s−1) and a true strain of 0.15 applied in one or two stages. The metallographic examinations and microhardness measurements were performed to assess the influence of the selected process parameters on the forming behaviour of the intermetallic zone. The experiments revealed that the main factors affecting the formability of the intermetallic zone in the two-layer AZ31/Al material were the strain rate and the temperature. It was found that when the deformation occurred at a strain rate of 0.1 s−1 and a temperature of 400 °C, there was no loss of continuity of the intermetallic transition zone; such conditions induced its plasticization.

7

Microstructure of the Bonding Zone Between AZ91 and AlSi17 Formed by Compound Casting

Mola R., Bucki T., Dziadoń A.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 1

202--206

EN

This paper discusses the joining of AZ91 magnesium alloy with AlSi17 aluminium alloy by compound casting. Molten AZ91 was cast at 650oC onto a solid AlSi17 insert placed in a steel mould under normal atmospheric conditions. Before casting, the mould with the insert inside was heated up to about 370oC. The bonding zone forming between the two alloys as a result of diffusion had a multiphase structure and a thickness of about 200 μm. The microstructure and composition of the bonding zone were analysed using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The results indicate that the bonding zone adjacent to the AlSi17 alloy was composed of an Al3Mg2 intermetallic phase with not fully consumed primary Si particles, surrounded by a rim of an Mg2Si intermetallic phase and fine Mg2Si particles. The bonding zone near the AZ91 alloy was composed of a eutectic (an Mg17Al12 intermetallic phase and a solid solution of Al and Si in Mg). It was also found that the compound casting process slightly affected the AZ91alloy microstructure; a thin layer adjacent to the bonding zone of the alloy was enriched with aluminium.

8

Characterization of the Surface Layer of Mg Enriched with Al and Si by Thermochemical Treatment

Mola R., Stępień E., Cieślik M.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 4

195--199

EN

The modified surface layers of Mg enriched with Al and Si were fabricated by thermochemical treatment. The substrate material in contact with an Al + 20 wt.% Si powder mixture was heated to 445ºC for 40 or 60 min. The microstructure of the layers was examined by OM and SEM. The chemical composition of the layer and the distribution of elements were determined by energy dispersive X-ray spectroscopy (EDS). The experimental results show that the thickness of the layer is dependent on the heating time. A much thicker layer (1 mm) was obtained when the heating time was 60 min than when it was 40 min (600 μm). Both layers had a non-homogeneous structure. In the area closest to the Mg substrate, a thin zone of a solid solution of Al in Mg was detected. It was followed by a eutectic with Mg17Al12 and a solid solution of Al in Mg. The next zone was a eutectic with agglomerates of Mg2Si phase particles; this three-phase structure was the thickest. Finally, the area closest to the surface was characterized by dendrites of the Mg17Al12 phase. The microhardness of the modified layer increased to 121-236 HV as compared with 33-35 HV reported for the Mg substrate.

9

Wytwarzanie warstwy wierzchniej wzbogaconej w cynk na magnezie przy użyciu pasty zawierającej chlorek cynku metodą obróbki cieplno-chemicznej

Bucki T., Mola R., Rzepa S.

Rudy i Metale Nieżelazne Recykling

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2016

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R. 61, nr 5

213--216

PL

Warstwę wierzchnią wzbogaconą w cynk na magnezie wytworzono metodą obróbki cieplno-chemicznej przy użyciu pasty zawierającej chlorek cynku. Próbki pokryte pastą wygrzewano w piecu komorowym w temperaturze 440oC przez okres 2 godz., bez używania atmosfery ochronnej. W wyniku tego procesu uzyskano na podłożu z magnezu warstwę wzbogaconą w cynk o grubości 200-240 μm. W mikrostrukturze warstwy zaobserwowano eutektoid składający się z fazy międzymetalicznej MgZn i roztworu stałego cynku w magnezie, na tle którego występowały dendryty roztworu stałego cynku w magnezie. Pomiędzy wytworzoną warstwą a podłożem magnezowym, zidentyfikowano cienką strefę przejściową zbudowaną z roztworu stałego cynku w magnezie. Mikrotwardość warstwy wzbogaconej w cynk wynosiła 110-164 HV0,1 i była 4-5 krotnie wyższa w stosunku do mikrotwardości podłoża-magnezu.

EN

A surface layer enriched with zinc was fabricated on a magnesium substrate by thermochemical treatment using a paste containing zinc chloride. Specimens painted with the paste were heated in a chamber furnace at 440oC for 2 h without protective atmosphere. The experimental results showed that the thickness of the alloyed layer was about 200-240 μm. The microstructure of the layer was comprised as eutectoid (an MgZn intermetallic phase + a solid solution of zinc in magnesium) and some dendrites of a solid solution of zinc in magnesium. At the interface between the alloyed layer and the magnesium substrate, there was a zone of a solid solution of zinc in magnesium. The microhardness of the Zn-rich layer was in the range of 110-164 HV0.1 and it was 4-5 times higher than that of the magnesium substrate.

10

Mechanical properties and corrosion behavior of nitrided surface layer formed on AISI 4140 steel

Jagielska-Wiaderek K., Makrenek M., Mola R.

Ochrona przed Korozją

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2016

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nr 7

248--251

EN

Investigation results under structure and physicochemical properties of glow-discharge nitrided (1:1 vol. N2/H2 atmosphere, 520°C) AISI 4140 steel are presented in the paper. The successive thinning method has been applied to determine the corrosion resistance changes within the cross-section of the nitrided layer. The method consists in step by step polarization corrosion measurements for successive surfacial layers. The potentiokinetic polarization tests were carried out in acidified (pH = 1) 0.5 M sulphate solution. The metallographically prepared specimens were observed with the use of optical microscopy and AFM microscopy. Microhardness measurements of the polished samples from the cross-section were carried out using Vickers indenter and the mechanical properties – using nanohardness meter, CSM, with a load of 80 mN.

PL

W pracy przedstawiono wyniki badań nad budową i właściwościami fizykochemicznymi warstw powierzchniowych stali 42CrMo4 po procesie azotowania jarzeniowego w atmosferze N2/H2 w temperaturze 520°C. Dla określenia zmian w odporności korozyjnej na przekroju poprzecznym warstwy azotowanej wykorzystano metodę postępującego ścieniania, która polega na wykonywaniu polaryzacyjnych testów korozyjnych na coraz głębiej położonych obszarach warstwy wierzchniej. Badania potencjokinetyczne wykonano w 0,5 M roztworze siarczanowym zakwaszonym do pH = 1. Badania metalograficzne prowadzono za pomocą mikroskopu optycznego oraz mikroskopu sił atomowych. Pomiaru rozkładu twardości w warstwie wierzchniej dokonywano metodą Vickersa, a właściwości mechaniczne oceniono przy użyciu nanotwardościomierz firmy CSM stosując obciążenie 80 mN.

11

Formation of Al-alloyed Layer on Magnesium with Use of Casting Techniques

Mola R., Bucki T., Dziadoń A.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 1

112--116

EN

Al-enriched layer was formed on a magnesium substrate with use of casting. The magnesium melt was cast into a steel mould with an aluminium insert placed inside. Different conditions of the casting process were applied. The reaction between the molten magnesium and the aluminium piece during casting led to the formation of an Al-enriched surface layer on the magnesium substrate. The thickness of the layer was dependent on the casting conditions. In all fabricated layers the following phases were detected: a solid solution of Mg in Al, Al3Mg2, Mg17Al120 and a solid solution of Mg in Al. When the temperature of the melt and the mould was lower (variant 1 – 670oC and 310oC; variant 2 – 680oC and 310oC, respectively) the unreacted thin layer of aluminium was observed in the outer zone. Applying higher temperatures of the melt (685oC) and the mould (325oC) resulted in deep penetration of aluminium into the magnesium substrate. Areas enriched in aluminium were locally observed. The Al-enriched layers composed mainly of Mg-Al intermetallic phases have hardness from 187-256 HV0.1.

12

Stopowanie powierzchni magnezu metodą spawalniczą przy użyciu drutu AlMg4,5Mn

Mola R., Dziadoń A., Bucki T.

Rudy i Metale Nieżelazne Recykling

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2015

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R. 60, nr 3

110--114

PL

Stopowanie powierzchni magnezu przeprowadzono metodą GTAW, jako materiał stopujący zastosowano drut AlMg4,5. Wytworzona warstwa stopowa miała grubość ok. 2 mm i cechowała się strukturą złożoną z dendrytów roztworu stałego aluminium w magnezie oraz eutektyki rozmieszczonej po granicach dendrytów. Eutektyka składała się z fazy międzymetalicznej Mg17Al12 oraz roztworu stałego aluminium w magnezie. Pomiędzy warstwą a podłożem stwierdzono występowanie cienkiej strefy przejściowej złożonej z roztworu stałego aluminium w magnezie. Mikrotwardość zmodyfikowanej warstwy wierzchniej była ponad dwukrotnie wyższa w porównaniu do mikrotwardości podłoża.

EN

Surface alloying of magnesium surface was conducted by GTAW using AlMg4.5Mn wire as the alloying material. The microstructure of the resulting surface layer comprised dendrites of the solid solution of aluminium in magnesium and a eutectic structure occurring in the interdendritic areas. The eutectic contained an Mg17Al12 intermetallic phase and a solid solution of aluminium in magnesium. At the interface between the layer and the substrate, a thin zone of the solid solution of aluminium in magnesium was observed. The microhardness of the modified surface was more than twice as high as that of the substrate.

13

The Influence of the Asymmetric ARB Process on the Properties of Al-Mg-Al Multi-Layer Sheets

Wierzba A., Mróz S., Szota P., Stefanik A., Mola R.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

2821--2826

EN

The paper presents the results of the experimental study of the three-layer Al-Mg-Al sheets rolling process by the ARB method. The tests carried out were limited to single-pass symmetric and asymmetric rolling processes. An Al-Mg-Al package with an initial thickness of 4 mm (1-2-1 mm) was subjected to the process of rolling with a relative reduction of 50%. To activate the shear band in the strip being deformed, an asymmetry factor of av=2 was applied. From the test results, an increase in the tensile strength of the multi-layer Al-Mg-Al sheets obtained from the asymmetric process was observed. Microhardness tests did not show any significant differences in aluminium layer between respective layers of sheets obtained from the symmetric and the asymmetric process. By contrast, for the magnesium layer, an increase in microhardness from 72 HV to 79 HV could be observed for the asymmetric rolling. The analysis of the produced Al-Mg-Al sheets shows that the good bond between individual layers and grain refinement in the magnesium layer contributed to the obtaining of higher mechanical properties in the multi-layer sheets produced in the asymmetric process compared to the sheets obtained from the symmetric process.

PL

W pracy przedstawiono wyniki badań doświadczalnych procesu walcowania metodą ARB trójwarstwowych blach Al- Mg-Al. W przeprowadzonych badaniach ograniczono się do jednoprzepustowego symetrycznego i asymetrycznego procesu walcowania. Procesowi walcowania poddano pakiet Al-Mg-Al o grubości początkowej 4 mm (1-2-1 mm) walcowany z gniotem względnym 50%. W celu aktywacji pasm ścinania w odkształcanym paśmie zastosowano współczynnik asymetrii av=2. Na podstawie wyników badań zaobserwowano wzrost wytrzymałości na rozciąganie wielowarstwowych blach Al- Mg-Al otrzymanych w procesie asymetrycznym. W wyniku przeprowadzonych badań mikrotwardości w poszczególnych warstwach dla blach otrzymanych w procesie symetrycznym i asymetrycznym nie stwierdzono istotnych różnic w wartościach mikrotwardości dla warstw aluminiowych. Natomiast dla warstwy magnezowej można było zaobserwować zwiększenie mikrotwardości z 72 HV do 79 HV - dla walcowania asymetrycznego. Analiza mikrostruktury otrzymanych blach Al-Mg- Al wskazuje, iż dobre połączenie pomiędzy poszczególnymi warstwami oraz rozdrobnienie ziarna w warstwie magnezu miały wpływ na uzyskanie wyższych właściwości mechanicznych w wielowarstwowych blachach otrzymanych w procesie asymetrycznym w porównaniu do blach wytworzonych w procesie symetrycznym.

14

Analysis of the Deformability of Two-Layer Materials AZ31/Eutectic

Mola R., Mróz S., Szota P., Sawicki S.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

3017--3022

EN

The paper present the results of physical simulation of the deformation of the two-layered AZ31/eutectic material using the Gleeble 3800 metallurgical processes simulator. The eutectic layer was produced on the AZ31 substrate using thermochemical treatment. The specimens of AZ31 alloy were heat treated in contact with aluminium powder at 445°C in a vacuum furnace. Depending on the heating time, Al-enriched surface layers with a thickness of 400, 700 and 1100 μm were fabricated on a substrate which was characterized by an eutectic structure composed of the Mg17Al12 phase and a solid solution of aluminium in magnesium. In the study, physical simulation of the fabricated two-layered specimens with a varying thickness of the eutectic layer were deformed using the plane strain compression test at various values of strain rates. The testing results have revealed that it is possible to deform the two-layered AZ31/eutectic material at low strain rates and small deformation values.

PL

W pracy przedstawiono wyniki modelowania fizycznego odkształcania materiału dwuwarstwowego AZ31/eutektyka z wykorzystaniem symulatora procesów metalurgicznych Gleeble 3800. Warstwę o strukturze eutektyki wytworzono na podłożu ze stopu magnezu w gatunku AZ31 metodą obróbki cieplno-chemicznej. Próbki ze stopu AZ31 wygrzewano w kontakcie z proszkiem aluminium w temp. 445°C w piecu próżniowym. Zależnie od zastosowanego czasu wygrzewania uzyskano na podłożu magnezowym warstwy wzbogacone w aluminium o grubościach 400, 700, 1100 μm i strukturze eutektycznej składającej się z fazy międzymetalicznej Mg17Al12 oraz roztworu stałego aluminium w magnezie. W ramach symulacji fizycznych otrzymane dwuwarstwowe próbki o różnych grubościach warstwy eutektyki odkształcano stosując próbę ściskania w płaskim stanie odkształcenia przy różnych prędkościach odkształcenia. Otrzymane wyniki badań wskazują na możliwość odkształcania dwuwarstwowego materiału AZ31/eutektyka z małymi prędkościami odkształcenia oraz przy stosunkowo małych wartościach odkształcenia.

15

Fabrication and Microstructure of Diffusion Alloyed Layers on Pure Magnesium Substrate

Mola R.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 4

1409--1412

EN

Alloyed layers on pure magnesium were created by means of the heating of the magnesium sample covered with Al+Zn powders mixture containing 20 wt.% Zn and 40 wt.% Zn in vacuum furnace. The microstructure and related composition of the alloyed layers were investigated using optical microscopy and scanning electron microscopy equipped with an energy dispersive X-ray system (EDS). The results revealed that the microstructure, thickness and microhardness of the obtained layers depended on the Zn content in the powder mixture. The alloyed layers were composed of the Mg-Al-Zn intermetallic phases and Mg-based solid solution containing Al and Zn. The multi-phase layer was diffusion bonded with magnesium substrate. The thickness of the layer fabricated by the heat treatment in contact with a powder mixture containing 40 wt.% Zn was twice as high as compared to that obtained with the powder mixture containing 20 wt.% Zn. The hardness value of the alloyed layers was much higher than that of the magnesium substrate.

PL

Warstwy stopowe na magnezie zostały wytworzone poprzez wygrzewanie próbek w kontakcie z mieszankami proszków Al+Zn zawierajacymi 20% mas. Zn i 40% mas. Zn w piecu próżniowym (oznaczone jako: Al20Zn i Al40Zn). Badania struktury i składu chemicznego przeprowadzono na mikroskopie optycznym oraz elektronowym mikroskopie skaningowym wyposażonym w mikroanalizator rentgenowski. Wyniki badań wykazały, że mikrostruktura, grubość oraz mikrotwardość otrzymanych warstw zależą od zawartości Zn w mieszankach proszków. Warstwy stopowe składały się z faz międzymetalicznych Mg-Al-Zn i roztworu stałego Al i Zn w Mg i były dyfuzyjnie połączone z podłożem-magnezem. Grubość warstwy wytworzonej na podłożu magnezowym poprzez wygrzewanie próbek w kontakcie z mieszanką proszków zawierającą 40% mas. Zn była dwa razy większa w porównaniu do warstwy otrzymanej w mieszance zawierającej 20% mas. Zn. Twardość otrzymanych warstw stopowych była znacznie wyższa w porównaniu do twardości podłoża.

16

Characterization of coatings on grey cast iron fabricated by hot-dipping in AlSi11 alloy

Mola R., Depczyński W.

Archives of Materials Science and Engineering

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2014

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Vol. 68, nr 1

20--23

EN

Purpose: In this study, grey cast iron was aluminized by hot-dip coating with AlSi11 alloy. The microstructure and chemical composition of the coatings were analyzed to determine the effect of the bath temperature on the thickness of the coating. Design/methodology/approach: Flake graphite cast iron was aluminized by hot-dipping in AlSi11 alloy at 700°C or 750°C for 20 min. The microstructure and phase composition of the coatings were determined by means of an optical microscope and a scanning electron microscope with an EDS X-ray analyzer. Findings: It was found that the overall thickness of a coating was dependent on the temperature of the bath. The coatings consisted of an outer layer with the composition similar to the aluminizing bath and an inner intermetallic layer and dispersed graphite. The outer layer was much thicker for coatings fabricated at a temperature of 750°C. The thickness of the inner layer was similar for both bath temperatures. The inner layer was composed of two zones: the Al5Fe2 phase, adjacent to the cast iron substrate and the Al5FeSi phase, adjacent to the Al-Si outer layer. The interface between the layer of the Al5Fe2intermetallic phases and the substrate showed flat morphology. The Al5FeSi phase-outer layer interface was irregular. Practical limitations/implications: The results obtained through the investigations show that the temperature of the Al-Si bath has influence on the overall thickness of the coating. The thickness of the outer layer increases with an increase in the bath temperature. The thickness of the inner layer, however, is not affected by the bath temperature. Originality/value: Coatings produced by hot-dipping in pure aluminium are characterized by a microstructure with a relatively thick inner layer of intermetallic phases.

17

The Properties of Al/Zn-enriched Surface Layers on Mg

Mola R.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 3 spec.

45--48

EN

The Al/Zn-enriched surface layers were fabricated on Mg substrate by heating the specimens in contact with an Al + 40 wt.% Zn powder mixture at 445oC for 60 min. The microstructure and corrosion and wear resistance of the layers were investigated and discussed. The experimental results show that the layers were composed of Mg17(Al,Zn)12 and Mg5Al2Zn2 intermetallic phases and a solid solution of Al and Zn in Mg. They were integrated with the substrate trough a zone of a solid solution of Al and Zn in Mg. The potentiodynamic polarization measurements indicated that the specimens with Al/Zn-enriched layer had better corrosion resistance than the bare Mg. The microhardness of the layers containing Mg-Al-Zn intermetallic phases was much higher than that of the Mg substrate. The sliding wear tests showed that the wear resistance of the specimens with a surface layer containing intermetallic phases was also superior to that of untreated Mg.

18

Characterization of Coatings on Grey Cast Iron Fabricated by Hot-dipping in Pure Al, AlSi11 and AlTi5 Alloys

Mola R., Bucki T., Wcisło K.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 1

85--90

EN

Flake graphite cast iron was hot-dip coated with pure aluminium or aluminium alloys (AlSi11 and AlTi5). The study aimed at determining the influence of bath composition on the thickness, microstructure and phase composition of the coatings. The analysis was conducted by means of an optical microscope and a scanning electron microscope with an EDS spectrometer. It was found that the overall thickness of a coating was greatly dependent on the chemical composition of a bath. The coatings consisted of an outer layer and an inner intermetallic layer, the latter with two zones and dispersed graphite. In all the cases considered, the zone in the inner intermetallic layer adjacent to the cast iron substrate contained the Al5Fe2 phase with small amount of silicon; the interface between this phase and the cast iron substrate differed substantially, depending on the bath composition. In the coatings produced by hot-dipping in pure aluminium the zone adjacent to the outer layer had a composition similar to that produced from an AlTi5 bath, the Al3Fe phase was identified in this zone. The Al3Fe also contained silicon but its amount was lower than that in the Al5Fe2. In the coatings produced by hot-dipping in AlSi11, the zone adjacent to the outer layer contained the Al3FeSi phase. The analysis results showed that when AlSi11 alloy was applied, the growth mode of the inner layer changed from inwards to outwards. The interface between the Al5Fe2 phase and the cast iron substrate was flat and the zone of this phase was very thin. Locally, there were deep penetrations of the Al5FeSi phase into the outer layer, and the interface between this phase and the outer layer was irregular. Immersion in an AlTi5 bath caused that the inner intermetallic layer was thicker than when pure aluminium or AlSi11 alloy baths were used; also, some porosity was observed in this layer; and finally, the interface between the inner layer and the cast iron substrate was the most irregular.

19

Charakterystyka mikrostruktury warstwy wierzchniej magnezu wzbogaconej w aluminium i krzem za pomocą lasera CO2

Dziadoń A., Mola R.

Rudy i Metale Nieżelazne

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2013

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R. 58, nr 10

551--556

PL

Artykuł przedstawia wyniki laserowego, powierzchniowego stopowania magnezu stopem AlSi20. Warstwa powierzchniowa magnezu została ukształtowana za pomocą lasera CO2 przy odpowiednio dobranych parametrach procesu stopowania. Twardość stopowanej warstwy wierzchniej wzrosła do 215-225 HV0,1 z 32 HV0,1 dla magnezu. Na podstawie mikroanalizy rentgenowskiej przedstawiono szczegółową charakterystykę mikrostruktury warstwy stopowanej. Stwierdzono, że mikrostruktura jest zależna od zawartości pierwiastków stopowych Al i Si w danej strefie warstwy wierzchniej. Z badań wynika, że dominująca (gruba) strefa warstwy wierzchniej zawiera głównie fazy: Mg2Si, roztwór stały magnezu w aluminium i Al3Mg2. W sąsiedztwie magnezu-podłoża zidentyfikowano cienką strefę zawierającą Mg17Al12 oraz r oztwór stały a luminium w magnezie. Strefę połączenia warstwy wierzchniej z magnezem stanowi roztwór stały aluminium w magnezie zawierający 5-10 % at. Al.

EN

In the work laser surface alloying of magnesium with AlSi20 alloy was presented. Surface layer was formed using a CO2 laser with appropriate processing parameters. The hardness of modified surface layer increased to 215-225 HV0,1 as compared to 32 HV0,1 for magnesium. On the basis of X-ray microanalysis a detailed characteristic of microstructure the laser alloyed layer was presented. It was found that the microstructure depends on content of alloying elements Al and Si in the zone of surface layer. The results showed that the dominant (thick) zone of surface layer consisted mainly of phases: Mg2Si, solid solution of magnesium in aluminium and Al3Mg2. In the neighbourhood of magnesium-substrate thin zone containing Mg17Al12 and solid solution aluminium in magnesium was identified. The bonding zone surface layer — magnesium is solid solution aluminium in magnesium containing 5-10 at. % Al.

20

Magnez – kierunki kształtowania własności mechanicznych

Dziadoń A., Mola R.

Obróbka Plastyczna Metali

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2013

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T. 24, nr 4

253--277

PL

Praca przedstawia w formie przeglądowej aktualny stan rozwoju technologii stopów magnezu. Zainteresowanie stopami magnezu ciągle rośnie, głównie z tego względu, że posiadają one dobrą wytrzymałość w połączeniu z niską gęstością. Artykuł zawiera charakterystykę podstawowych stopów magnezu i przegląd głównych metod, które pozwalają wpływać na ich własności. Przede wszystkim przeanalizowano proces starzenia stopów magnezu. Wykazano, na przykładzie stopu AZ91, że poddane obróbce cieplnej stopy magnezu wykazują słabsze umocnienie w porównaniu do stopów o osnowie aluminium. Z drugiej strony, rozdrobnienie ziarna wywiera znacznie większy niż w przypadku stopów aluminium i stopów innych metali wpływ na umocnienie magnezu i jego stopów. Artykuł zawiera także przegląd najnowszych prac dotyczących kompozytów o osnowie magnezu. W szczególności przedstawiono sposób wytwarzania makro-kompozytu warstwowego magnez-fazy międzymetaliczne. Pokazano również, że istnieje możliwość znaczącej zmiany mikrostruktury i własności warstwy wierzchniej magnezu za pomocą obróbki laserowej.

EN

The work gives an overview on the actual status of the technology development of magnesium alloys. Interest in the magnesium alloys is still growing mainly because they combine good strength and low density. Article contains characteristics of fundamental magnesium alloys and review of main methods of influencing on their properties. First of all, ageing behaviour of magnesium alloys was analyzed. It has been shown, giving an example AZ91 alloy, that the heat treated magnesium alloys exhibit weaker strengthening effect compared to aluminum-base alloys. On the other hand, effect of the grain refining on strengthening in magnesium and magnesium alloys is much higher than that for aluminum alloys and for alloys of other metals. A paper contains a review of the recent works concerning the magnesium matrix composites. In particularly, a method of manufacturing magnesium-intermetallic phases layered macro-composite was presented. It was also shown that there exists possibility of significant modification of the microstructure and properties of the surface layer of magnesium using the laser treatment.