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EN
The paper presents an analysis of a selected grade of high silicon cast iron intended for work in corrosive and abrasive conditions. The text describes its microstructure taking into account the process of crystallization, TDA analysis, EDS, XRD and the chemical composition analysis. In order to determine the phase composition, X-ray diffraction tests were carried out. The tests were executed on a Panalytical X'Pert PRO X-ray diffractometer with filtration of radiation from a lamp with copper anode and PIXcel 3D detector on the deflected beam axis. Completed tests allowed to describe the microstructure with detailed consideration of intermetallic phases present in the alloy. Results of the analysis of the examined alloy clearly show that we deal with intermetallic phases of Fe3Si, Fe5Si3 types, as well as silicon ferrite and crystals of silicon. In the examined alloy, we observed the phenomenon of segregation of carbon, which, as a result of this process, enriches the surface of silicon crystals, not creating a compound with it. Moreover, the paper demonstrates capability for crystallization of spheroidal graphite in the examined alloy despite lack of elements that contribute to balling in the charge materials.
EN
The quality of aluminum casts is necessary in order to reach sufficient properties required for application. The decreasing in the properties of aluminum cast mainly related with microstructure, especially with size and morphology of second phases. One of such second phases in aluminum alloys are the β-phases. These phases are unwonted mainly because of the decreasing of mechanical properties. The contribution is deal with influence of addition of Mn to affecting the formation of βphases in the AlSi7Mg0.3 and AlSi7Mg0.6 cast alloys. These materials are used for application especially automotive industry. The results shows, that addition of Mn is not sufficient for affecting of formation of the Fe-rich phases in AlSi7Mg0.6 cat alloys, but in the AlSi7Mg0.3 this addition lead to changes in formation of Fe-rich intermetallic phases.
EN
This article deals with the effect of manganese that is the most applied element to eliminate the negative effect of iron in the investigated alloy AlSi7Mg0.3. In this time are several methods that are used for elimination harmful effect of iron. The most used method is elimination by applying the additive elements, so-called iron correctors. The influence of manganese on the morphology of excluded iron-based intermetallic phases was analysed at various iron contents (0.4; 0.8 and 1.2 wt. %). The effect of manganese was assessed in additions of 0.1; 0.2; 0.4 and 0.6 wt. % Mn. The morphology of iron intermetallic phases was assessed using electron microscopy (SEM) and EDX analysis. The increase of iron content in investigated alloys caused the formation of more intermetallic phases and this effect has been more significant with higher concentrations of manganese. The measurements carried out also showed that alloys with the same Mn/Fe ratio can manifest different structures and characteristics of excluded iron-based intermetallic phases, which might, at the same time, be related to different resulting mechanical properties.
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.
5
Content available remote The FeAl coatings deposited by Laser Engineered Net Shaping
EN
The process of manufacturing FeAl coatings by LENS method was presented in this work. The spherical alloy powder of Fe40Al0.05Zr–50 ppm B (at. %) was used as a row material for deposition protective coating on turbine blades. The layered coatings with Ni or 316L zone were also considered. Samples were prepared using LENS 850R system with 1000 W fiber laser and two independently controlled powder feeders. The microscopic examination showed that each technological variants have porosity inherited of porosity of powder particle. A scanning with 700 W of laser beam of deposition area enables substantial elimination of this discontinuities type. The positive effect of this technological solution was also noted for microhardness distribution of samples. The deposited coatings is characterized by 600 HV of microhardness with smooth transition zone between coating/substrate. The strength test (three-point bending) showed the mechanical properties of FeAl samples prepared with LENS are lower by about thirty percent (bending strength, ductility) than the substrate.
PL
Materiały na osnowie fazy FeAl stanowią trudną technologicznie grupę „intermetalików”, będącą atrakcyjną alternatywą dla drogich stopów żarowytrzymałych. Obecnie poszukuje się nowych metod przetwarzania tego typu tworzyw, ze szczególnym uwzględnieniem technik przyrostowych. Celem pracy było wielowariantowe wytwarzanie napoin FeAl techniką laserowego kształtowania przyrostowego LENS połączone z oceną ich jakości metalurgicznej i wybranych właściwości użytkowych.
EN
Purpose: The main purpose of this paper was to determine the influence of the temperature of solution heat treatment on the microstructure and hardness of the newly designed model alloy, intended for working at high temperatures. Design/methodology/approach: A mass weighing approx. 1 kg was test melted in a vacuum furnace and cast into a ceramic mould. Samples for investigations were solution heat treated at the temperature range of 1020-1170°C. After heating to the desired temperature, the samples were held at this temperature for 2 hours and then water-cooled. Findings: The main constituents of the microstructure of the Ni-Co-Cr-Ta-Al-C alloy in as-cast state are: the γ phase, which constitutes the matrix, the γ’ phase (γ’ phase occurs as fine globular precipitates) as well as primary TaC and Cr7C3 carbides. Irregularly shaped primary carbides are uniformly distributed and do not form agglomerates. Solution heat treatment of the investigated alloy at exceedingly higher temperatures causes a slow decrease of chromium primary carbides. Research limitations/implications: Taking into account the chemical composition of the investigated alloy, it is reasonable to expect the heat treatment should improve its properties. At 1020°C, γ’ phase precipitations dissolve and it is possible to achieve a super saturated solid solution matrix. Next, correct aging treatment should by applied. Practical implications: A new model alloy which allows to design a new material for high temperature applications. Originality/value: New chemical compositions and microstructure of Ni-based materials for high temperature application with high carbon contents. Additionally, the new alloy is strengthened not only by a high carbon volume fraction but also by intermetallic phases.
EN
In Al-Si alloy the iron is the most common impurity and with presence of other elements in alloy creates the intermetallic compounds, which decreases mechanical properties and increases of porosity. The cause of the negative effect of intermetallic particles on the mechanical properties is that it is more easily break off the tension load as the aluminium matrix or small particles of silicon. By adding suitable alloying elements, also known as iron correctors, is possible to reduce this harmful effect. In the article is evaluated influence of manganese on microstructure with performed EDX analysis selected intermetallic phases and tensile test and measurement of length of Al5FeSi phase. For realization experiments was used AlSi7Mg0.3 alloy with increased iron content. Manganese was added in the amount 0.3 wt. %, 0.6 wt. %, 0.8 wt.% and 1,2 wt. %. From performed measurements it has been concluded, that increased amount of manganese, i.e. Mn/Fe ratio, does not have significant influence on mechanical properties AlSi7Mg0.3 alloy in the melted state.
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.
EN
Manganese is an effective element used for the modification of needle intermetallic phases in Al-Si alloy. These particles seriously degrade mechanical characteristics of the alloy and promote the formation of porosity. By adding manganese the particles are being excluded in more compact shape of “Chinese script” or skeletal form, which are less initiative to cracks as Al5FeSi phase. In the present article, AlSi7Mg0.3 aluminium foundry alloy with several manganese content were studied. The alloy was controlled pollution for achieve higher iron content (about 0.7 wt. % Fe). The manganese were added in amount of 0.2 wt. %, 0.6 wt. %, 1.0 wt. % and 1.4 wt. %. The influence of the alloying element on the process of crystallization of intermetallic phases were compared to microstructural observations. The results indicate that increasing manganese content (> 0.2 wt. % Mn) lead to increase the temperature of solidification iron rich phase (TAl5FeSi) and reduction this particles. The temperature of nucleation Al-Si eutectic increase with higher manganese content also. At adding 1.4 wt. % Mn grain refinement and skeleton particles were observed.
10
Content available remote In situ TEM observation of reaction of Ti/Al multilayers
EN
The Ti/Al multilayers of nominal periods λ = 50 nm and λ = 200 nm were deposited using double target magnetron system equipped with rotating substrate holder. The in situ TEM experiments were aimed at explaining DSC measured exothermic effects through phase transformations taking place during heating of the multilayers with small and large period. Thin foils for these examinations were cut with FIB. The performed experiments showed that the as deposited multilayers are characterized by presence of coarse pseudo-columnar crystallites built of alternating hex-Ti and fcc-Al. The intermixed region at the internal interfaces extends up to 10 nm, i.e. the areas filled with mutually alloyed material starts to dominate over those of pure metals for multilayers of λ < 30 nm. The DSC measurements indicated that in both multilayers their reaction are split to two stages, but those in the small period take place at much lower temperature range, than that in the large period one.
EN
Microscopic observations and quantitative analysis of the microstructure image were used to analyze the solidification course and morphology evolution in polyphase eutectics in the AlSi casting alloys with transition metals Fe and Mn. The utility of the analytical test procedures was demonstrated. It was stated that their precision and repeatability should be improved. Further works on quantitative morphological coefficients used as objective discriminators of the particular morphological form of phase constituents should be continued. Nevertheless, obtained results of the microstructure image analysis indicated that in a concentration range of transition metals: Fe 0.5−1.5 wt. % and Mn 0−0.5 wt. %, the total Vv of the eutectic intermetallics has increased with a total content of the transition metals (Fe + Mn). In both group of alloys hypo- and eutectic the final results of the competition between phases αc-AlFeMnSi, αH-AlFeSi and β-AlFeSi have been explained as affected by non-equilibrium microsegregation of Fe, Mn and Si in solidifying liquid, and by the actual value of the Fe/Si coefficient. Preferences for αc-AlFeMnSi phase were reinforced by a decrease in the value of Fe/Mn coefficient.
PL
Obserwacje mikroskopowe oraz ilościowa analiza obrazu mikrostruktury zostały wykorzystane do analizy ścieżki krystalizacji i ewolucji morfologii wielofazowych eutektyk zawierających fazy międzymetaliczne w stopach AlSi zawierających metale przejściowe. Wykazano przydatność opracowanej procedury badawczej, jakkolwiek jej precyzja i powtarzalność będą mogły być poprawione tylko na drodze dalszych prac nad ustanowieniem obiektywnych reguł klasyfikacji opartej na ilościowym wskaźniku morfologicznym jako dyskryminatorze dla grup morfologicznych, przypisanych do składników fazowych mikrostruktury. Niemniej jednak otrzymane wyniki analizy obrazu mikrostruktury wykazały, że w zakresie stężenia 0,5−1,5% Fe i 0−0,5% Mn całkowita wartość objętości względnej Vv faz międzymetalicznych AlFeMnSi zwiększała się w miarę wzrostu zawartości metali przejściowych (Fe + Mn) w stopie. W obu grupach stopów, podeutektycznych i eutektycznych, mikrostrukturalny wynik konkurencji pomiędzy fazami αH-AlFeSi i β-AlFeSi był uzależniony od nierównowagowej mikrosegregacji Fe, Mn i Si w cieczy resztkowej, w tym od trzeczywistych zmian wartości wskaźnika Fe/Si. Preferencje dla fazy αc-AlFeMnSi wzmacniane były zmniejszeniem wartości wskaźnika Fe/Mn.
EN
Thermodynamic model for the diffusion barrier formation in the Al/Ni nano-foil is presented. Two types of diffusion are distinguished in the model, boundary diffusion for substrate dissolution and bulk diffusion for solidification. The creation of two phases: Al3Ni, Al3Ni2 in the diffusion barrier are predicted due to the cyclical manner of the dissolution and solidification occurrence.
PL
Przedstawiony jest termodynamiczny model formowania bariery dyfuzyjnej w nano-folii Al/Ni. Wyróżniono dwa typy dyfuzji, dyfuzję graniczną dla rozpuszczania oraz dyfuzję objętościową dla krystalizacji. Przewidziano tworzenie się dwu faz: Al3Ni, Al3Ni2 w barierze dyfuzyjnej stosownie do cyklicznego przebiegu rozpuszczania i krystalizacji.
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.
EN
Duplex Stainless Steels (DSS) and Super Duplex Stainless Steel (SDSS) have excellent integration of mechanical and corrosion properties. However, the formation of intermetallic phases is a major problem in their usage. The mechanical and corrosion properties are deteriorated due to the presence of intermetallic phases. These phases are induced during welding, prolonged exposure to high temperatures, and improper heat treatments. The main emphasis of this review article is on intermetallic phases and their effects on corrosion and mechanical properties. First the effect of various alloying elements on DSS and SDSS has been discussed followed by formation of various intermetallic phases. The intermetallic phases affect impact toughness and corrosion resistance significantly. Their deleterious effect on weldments has also been reviewed.
EN
The main objective of this work was to examine a solidification process of AlCu4Ni2Mg2 alloy and analyze morphology and composition of the complex microstructure of intermetallic phases in as-cast condition. To study the solidification process differential scanning calorimetry (DSC) was used. To identify intermetallics in AlCu4Ni2Mg2 alloy optical light microscopy (LM), X-ray diffraction (XRD), scanning (SEM) and transmission (TEM) electron microscope and were used. The results show that the as-cast microstructure of AlCu4Ni2Mg2 alloy after slow solidification at a cooling rate 5°/min, consisted: dendrites of α-Al and intermetallic phases Al7Cu4Ni, Al6Fe, S-Al2CuMg, and Al3(CuFeNi)2 and Al2Cu.
PL
Prowadzono analizę procesu krystalizacji oraz składu chemicznego i morfologii składników fazowych mikrostruktury stopu AlCu4Ni2Mg2 w stanie lanym. W analizie procesu krystalizacji stopu stosowano metodę różnicowej kalorymetrii skaningowej (DSC). Identyfikację składników fazowych mikrostruktury stopu AlCu4Ni2Mg2 prowadzono metodami mikroskopii świetlnej (LM), elektronowej: skaningowej (SEM) i transmisyjnej (TEM) oraz dyfrakcji rentgenowskiej (XRD). Analiza uzyskanych wyników badań pozwoliła ustalić, że mikrostruktura stopu AlCu4Ni2Mg2, kształtowana w procesie krystalizacji z małą prędkością chłodzenia 5°C/min, składa się z dendrytów roztworu stałego α-Al oraz wydzieleń faz międzymetalicznych: Al7Cu4Ni, Al6Fe, S-Al2CuMg, Al3(CuFeNi)2 i Al2Cu.
EN
This paper assesses the effect of various values of detonation velocity on the quality of the bond zone, and thus the properties of bimetal zirconium (Zr 700) - steel (P355NL). The research was carried out for as-bonded welds, i.e. immediately following explosion welding. The results of shearing, peeling and tensile tests as well as macro-scale structural analyses were presented. In order to determine the changes in the value of strain hardening, the microhardness measurements across the interface were carried out. Based on the performed analyses it can be claimed that, depending on the applied technological settings of welding, most cases displayed wavy bond with highly diversified parameters of the wave. The changes observed with the detonation velocity are non-monotonic. High detonation velocities favored the formation of waves with large height and length and strongly affect the increase of the volume of brittle melted zones. Increased volume of the melted regions results in strong decrease of strength properties of the clad. The analysis of strength test results allows claiming that a small volume of melted regions in the bond considerably improves the strength of the bond. As a result of explosion welding, strain hardening of the joined materials occurs near the interface. In the case of clad fabricated using high technological parameters the increase of strengthening and the depth of its influence in the interface area is observed.
PL
W pracy poddano ocenie wpływ zróżnicowanych wartości prędkości detonacji na jakość strefy połączenia, a tym samym własności bimetalu w układzie cyrkon (Zr 700) – stal (P355NL). Badania prowadzono dla złączy w stanie wyjściowym, tj. bezpośrednio po zgrzewaniu wybuchowym. Przedstawiono wyniki badań mechanicznych (próba ścinania, zginania bocznego, odrywania oraz rozciągania) oraz strukturalnych w skali makro. Obserwacje strukturalne w pobliżu strefy połączenia umożliwiły określenie charakterystyki granicy połączenia. W celu określenia zmian w wielkości umocnienia wykonano pomiary mikrotwardości w obszarze złącza, jak i warstwy nakładanej oraz podstawowej. W zależności od zastosowanych parametrów technologicznych procesu spajania uzyskano połączenie faliste o silnie zróżnicowanych parametrach fali. Zmiany obserwowane wraz ze wzrostem prędkości detonacji są niemonotoniczne. Duże prędkości detonacji sprzyjały tworzeniu się fali o dużej wysokości i długości oraz wyraźnemu wzrostowi udziału twardych i kruchych obszarów przetopień w strefie połączenia. Zwiększony udział obszarów przetopień powodował drastyczny spadek własności wytrzymałościowych platerów. Układy o optymalnej charakterystyce granicy połączenia oraz odpowiednio wysokich własnościach wytrzymałościowych otrzymano przy niskich wartościach prędkości detonacji. W wyniku procesu spajania następowało umocnienie obydwu łączonych materiałów w pobliżu granicy rozdziału.
EN
This paper assesses the effect of various values of detonation velocity on the quality of the bond zone, and thus the properties of bimetal zirconium (Zr 700) - steel (P355NL). The research was carried out for as-bonded welds, i.e. immediately following explosion welding. The results of shearing, peeling and tensile tests as well as macro-scale structural analyses were presented. In order to determine the changes in the value of strain hardening, the microhardness measurements across the interface were carried out. Based on the performed analyses it can be claimed that, depending on the applied technological settings of welding, most cases displayed wavy bond with highly diversified parameters of the wave. The changes observed with the detonation velocity are non-monotonic. High detonation velocities favored the formation of waves with large height and length and strongly affect the increase of the volume of brittle melted zones. Increased volume of the melted regions results in strong decrease of strength properties of the clad. The analysis of strength test results allows claiming that a small volume of melted regions in the bond considerably improves the strength of the bond. As a result of explosion welding, strain hardening of the joined materials occurs near the interface. In the case of clad fabricated using high technological parameters the increase of strengthening and the depth of its influence in the interface area is observed.
PL
W pracy poddano ocenie wpływ zróżnicowanych wartości prędkości detonacji na jakość strefy połączenia, a tym samym własności bimetalu w układzie cyrkon (Zr 700) – stal (P355NL). Badania prowadzono dla złączy w stanie wyjściowym, tj. bezpośrednio po zgrzewaniu wybuchowym. Przedstawiono wyniki badań mechanicznych (próba ścinania, zginania bocznego, odrywania oraz rozciągania) oraz strukturalnych w skali makro. Obserwacje strukturalne w pobliżu strefy połączenia umożliwiły określenie charakterystyki granicy połączenia. W celu określenia zmian w wielkości umocnienia wykonano pomiary mikrotwardości w obszarze złącza, jak i warstwy nakładanej oraz podstawowej. W zależności od zastosowanych parametrów technologicznych procesu spajania uzyskano połączenie faliste o silnie zróżnicowanych parametrach fali. Zmiany obserwowane wraz ze wzrostem prędkości detonacji są niemonotoniczne. Duże prędkości detonacji sprzyjały tworzeniu się fali o dużej wysokości i długości oraz wyraźnemu wzrostowi udziału twardych i kruchych obszarów przetopień w strefie połączenia. Zwiększony udział obszarów przetopień powodował drastyczny spadek własności wytrzymałościowych platerów. Układy o optymalnej charakterystyce granicy połączenia oraz odpowiednio wysokich własnościach wytrzymałościowych otrzymano przy niskich wartościach prędkości detonacji. W wyniku procesu spajania następowało umocnienie obydwu łączonych materiałów w pobliżu granicy rozdziału.
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.
19
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.
EN
The aim of the research was to evaluate influence of porosity size on mechanical properties of AlSi7Mg0.3 (EN AC 42 100) alloy before and after thermal treatment. The castings from the same production type (forms used for tires production) were used for the analysis. They were casted using low-pressure casting technology. Since the negative influence of porosity on mechanical properties of Al alloys is generally known that there is no quantitative assessment. The relation of porosity size in the structure of AlSi7Mg0.3 alloy and its mechanical properties is verified and quantified in this research. Static tensile testing has proven the relation between porosity size in a structure of an Al material and its mechanical properties. The image analysis was applied in quantitative measurement of the porosity. The measurement was performed on prepared metallographic specimens. Porosity size is considered as a fraction of pore area to the total area of the analyzed specimen and is taken in percentage. As far as the theoretical part of the issue the possible causes of porosity formation and its influence on particular Al alloy types are described [1, 2, 3].
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