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Number of results: 139
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Abstract

The paper presents results of a study concerning an AlSi7Mg alloy and the effect of subjecting the liquid metal to four different processes: conventional refining with hexachloroethane; the same refining followed by modification with titanium, boron, and sodium; refining by purging with argon carried out in parallel with modification with titanium and boron salts and strontium; and parallel refining with argon and modification with titanium, boron, and sodium salts. The effect of these four processes on compactness of the material, parameters of microstructure, and fatigue strength of AlSi7Mg alloy after heat treatment. It has been found that the highest compactness (the lowest porosity ratio value) and the most favorable values of the examined parameters of microstructure were demonstrated by the alloy obtained with the use of the process including parallel purging with argon and modification with salts of titanium, boron, and sodium. It has been found that in the fatigue cracking process observed in all the four variants of the liquid metal treatment, the crucial role in initiation of fatigue cracks was played by porosity. Application of the process consisting in refining by purging with argon parallel to modification with Ti, B, and Na salts allowed to refine the microstructure and reduce significantly porosity of the alloy extending thus the time of initiation and propagation of fatigue cracks. The ultimate effect consisted in a distinct increase of the fatigue limit value.
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Abstract

Between 2004 and 2017, multiple studies on the herbicide resistance of weeds were conducted by the Institute of Plant Protection – National Research Institute in Poland. Weed seeds, collected from fields located in various regions of Poland where herbicide use was ineffective, were used in studies conducted under greenhouse conditions. A total of 261 loose silky bent (Apera spica-venti L.) samples were found to be herbicide resistant, which translates to 52.4% of the fields under study. Nearly 50% of the analyzed samples exhibited resistance to sulfonylurea herbicides. Resistance to acetyl CoA carboxylase (ACCase) inhibitors was found in 18 fields, whereas resistance to photosystem II (PSII) inhibitors (isoproturon) was found in 12 fields. Herbicide resistance of blackgrass (Alopecurus myosuroides Huds.) occurred in 26 of the fields under study. In addition, resistance of wild oat (Avena fatua L.) to acetyl CoA carboxylase inhibitors occurred in 10 spring cereal crops. In the case of winter wheat, resistance of cornflower (Centaurea cyanus L.) to tribenuron-methyl occurred in 23 fields. Scentless chamomile (Matricaria inodora L.) and field poppy (Papaver rhoeas L.) were resistant to tribenuron-methyl in four and three fields, respectively, of winter wheat. In the case of sugar beet, three biotypes of fat hen (Chenopodium album L.) and two biotypes of redroot amaranth (Amaranthus retroflexus L.) were resistant to metamitron. Horseweed (Conyza canadensis L.), which grows on railway tracks, exhibited resistance to glyphosate. This paper reviews all studies conducted in Poland on weed resistance. Based on the results, maps of weed resistance in Poland were created.
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Abstract

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 ironbased 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.
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Abstract

This article deals with Janusz Makarczyk’s bestselling historical romance Jafar of Baghdad, first published in 1950. Makarczyk had a varied career as a journalist, travel writer of the ‘globtrotter school’, military officer, diplomat and academic; his deep involvement with the Middle East and Arab history began in the 1926 when he was sent to the Polish consulate in Jerusalem. The life of Jafar ibn Yahya provided him not only with enough material for a gripping story of love and romance but also a pretext for painting a broad canvas of historical events and personages. Addressed to younger readers, the book is didactic in the sense that it offers them basic information about Islam (e.g. the division between the sunni and the shia) as well as lots of facts about the Arab world at the peak of the Abbasid Age (e.g. Harun al-Rashid and the struggle for his succession; rise and fall of the powerful Barmakid family, Harun al-Rashid’s half-sister Abassa; the great Islamic jurists Malik ibn Anas, Muhammad al-Shaybani and Al-Shafi ‘i; an assortment of poets and scholars, including the translator Ibn al-Muqaffa). In addition to countless allusions to the Book of the Thousand Nights and One Night, the narrative is encrusted with explicit and covert quotes from the Qur’an, Arabic adages and proverbs (32), the poems of Abu-l-’Atahiya and Abu Nuwas. The writer is aware that the allusions and learned references need to be contextualized in a way that is functional and that their incorporation into the main text must be handled with maximum flexibility. The great popularity of Jafar of Baghdad in its time can be taken as proof that Makarczyk did succeed in bringing the two functions of his novel, the cognitive and the aesthetic – to instruct and to please – into a harmonious whole.
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Abstract

This article deals with the fatigue properties of newly used AlZn10Si8Mg aluminium alloy where the main aim was to determine the fatigue strength and compare it with the fatigue strength of AlSi7Mg0.3 secondary aluminium alloys which is used in the automotive industry for cyclically loaded components. AlZn10Si8Mg aluminium alloy, also called UNIFONT 90, is self-hardening (without heat treatments), which contributes to economic efficiency. This is one of the main reasons why is compared, and may be an alternative replacement for AlSi7Mg0.3 alloy which is heat treated to achieve required mechanical properties. The experiment results show that the fatigue properties of AlZn10Si8Mg alloy are comparable, if not better, than AlSi7Mg0.3 alloy. Fatigue properties of AlZn10Si8Mg alloy are achieved after seven days of natural ageing, immediately after casting and achieving value of fatigue strength is caused by structural components formed during solidification of the melt.
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Abstract

An understanding of the fundamental correlation between grain size and material damping is crucial for the successful development of structural components offering high strength and good mechanical energy absorption. With this regard, we fabricated aluminum sheets with grain sizes ranging from tens of microns down to 60 nm and investigated their tensile properties and mechanical damping behavior. An obvious transition of the damping mechanism was observed at nanoscale grain sizes, and the underlying causes by grain boundaries were interpreted.
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Abstract

The aim of this paper was to determine the effect of heat treatment for the corrosion resistance of the ZnAl40Ti2Cu alloy under “acid rain” conditions. ZnAl40TiCu alloy after supersaturation and after supersaturation and aging was studied. Potentiodynamic studies, potentiostatic studies and studies on structure of the alloy top layer of samples after corrosion tests were carried out. These investigations indicated a significant influence of heat treatment on corrosion resistance of the ZnAl40Ti2Cu alloy. The highest increase in corrosion resistance comparing to the alloy in the as-cast condition may be obtained by supersaturation. A significant influence of the aging temperature and time on corrosion resistance was proved.
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Abstract

The main reason of a cavitational destruction is the mechanical action of cavitation pulses onto the material’s surface. The course of cavitation destruction process is very complex and depends on the physicochemical and structural features of a material. A resistance to cavitation destruction of the material increases with the increase of its mechanical strength, fatigue resistance as well as hardness. Nevertheless, the effect of structural features on the material’s cavitational resistance has been not fully clarified. In the present paper, the cavitation destruction of ZnAl4 as cast alloy was investigated on three laboratory stands: vibration, jet-impact and flow stands. The destruction mechanism of ZnAl4 as cast alloy subjected to cavitational erosion using various laboratory stands is shown in the present paper.
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Abstract

Secondary or multiple remelted alloys are common materials used in foundries. For secondary (recycled) Al-Si-Cu alloys, the major problem is the increased iron presence. Iron is the most common impurity and with presence of other elements in alloy creates the intermetallic compounds, which may negatively affect the structure. The paper deals with effect of multiple remelting on the microstructure of the AlS9iCu3 alloy with increased iron content to about 1.4 wt. %. The evaluation of the microstructure is focused on the morphology of iron-base intermetallic phases in caste state, after the heat treatment (T5) and after natural aging. The occurrence of the sludge phases was also observed. From the obtained results can be concluded that the multiple remelting leads to change of chemical composition, changes in the final microstructure and also increases sludge phases formation. The use of heat treatment T5 led to a positive change of microstructure, while the effect of natural aging is beneficial only to the 3rd remelting.
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Abstract

The high mechanical properties of the Al-Li-X alloys contribute to their increasingly broad application in aeronautics, as an alternative forthe aluminium alloys, which have been used so far. The aluminium-lithium alloys have a lower specific gravity, a higher nucleation andcrack spread resistance, a higher Young’s module and they characterize in a high crack resistance at lower temperatures. The aim of theresearch planned in this work was to design an aluminium alloy with a content of lithium and other alloy elements. The research includedthe creation of a laboratorial melt, the microstructure analysis with the use of light microscopy, the application of X-ray methods to identify the phases existing in the alloy, and the microhardness test.
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Abstract

The paper deals with the influence of manganese in AlSi7Mg0.3 alloy with higher iron content. Main aim is to eliminate harmful effect of intermetallic – iron based phases. Manganese in an alloy having an iron content of about 0.7 wt. % was graded at levels from 0.3 to 1.4 wt. %. In the paper, the effect of manganese is evaluated with respect to the resulting mechanical properties, also after the heat treatment (T6). Morphology of the excluded intermetallic phases and the character of the crystallisation of the alloy was also evaluated. From the obtained results it can be concluded that the increasing level of manganese in the alloy leads to an increase in the temperature of the β-Al5FeSi phase formation and therefore its elimination. Reducing the amount of β-Al5FeSi phase in the structure results in an improvement of the mechanical properties (observed at levels of 0.3 to 0.8 wt. % Mn). The highest addition of Mn (1.4 wt.%) leads to a decrease in the temperature corresponding to the formation of eutectic silicon, which has a positive influence on the structure, but at the same time the negative sludge particles were also present
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Abstract

The paper deals with squeeze casting technology. For this research a direct squeeze casting method has been chosen. The influence of process parameters variation (casting temperature, mold temperature, pressure) on mechanical properties and structure will be observed. The thicknesses of the individual walls were selected based on the use of preferred numbers and series of preferred numbers (STN ISO 17) with the sequence of 3.15, 4.00, 5.00, 6.00 and 8.00 mm. The width of each wall was 22 mm with a length of 100 mm. As an experimental material was chosen the AlSi12 and AlSi7Mg0.3 alloys. The mechanical properties (UTS, E) for individual casting parameters and their individual areas of different thicknesses were evaluated. In the structure the influence of pressure on the change of the eutectic morphology, the change of the volume of eutectic and the primary alpha phase, the effect of the pressure on the more fine-grain and the regularization of the structure were evaluated.
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Abstract

This paper deals with influence on segregation of iron based phases on the secondary alloy AlSi7Mg0.3 microstructure by chrome. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich phases. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition some other elements that affect the segregation of intermetallics in less harmful type. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases. By experimental work were used three different amounts of AlCr20 master alloy a three different temperature of chill mold. Our experimental work confirmed that chrome can be used as an iron corrector in Al-Si alloy, due to the change of intermetallic phases and shortening their length.
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Abstract

In this work, the effect of the microstructure on corrosion behavior of selected Mg- and Al-based as cast alloys, was evaluated. The electrochemical examinations were carried out, and then a morphology of corrosion products formed due to local polarization on materials surface, was analyzed. It was documented that the presence of Mg2Si phase plays an important role in the corrosion course of Mg-based alloy. A selective etching was observed in sites of Mg2Si precipitates having “Chinese script”- like morphology. Analogous situation was found for Al-based alloy, where the key role was played by cathodic θ-CuAl2 phase.
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Abstract

Iron is presented as an impurity in Al-Si alloys and occurs in the form of the β-Al5FeSi phase formations. The presence of iron and other elements in the alloy causes the formation of large intermetallic phases. Due to the high brittleness of this phase, it reduces the mechanical properties and increases the porosity. Manganese is used to inhibit the formation of this detrimental phase. It changes the morphology of the phase to polyhedral crystals, skeletal formations, or Chinese script. The present article deals with the influence of various amounts of manganese (0.1; 0.2; 0.4; 0.6 wt. %) on the formation of iron-based intermetallic phases in the AlSi7Mg0.3 alloy with different levels of iron content (0.4; 0.8, 1.2 wt. %). The increase of iron content in each alloy caused the creation of more intermetallic compounds and this effect has been more significant with higher concentrations of manganese. In alloys where the amount of 1.2 wt. % iron is present, the shape of eutectic silicon grain changes from angular to short needle type.
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Abstract

This study presents an analysis of aluminium cast iron structure (as-cast condition) which are used in high temperatures. While producing casts of aluminium iron, the major influence has been to preserve the structure of the technological process parameters. The addition of V, Ti, Cr to an Fe-C-Al alloy leads to the improvement of functional and mechanical cast qualities. In this study, a method was investigated to eliminate the presence of undesirable Al4C3 phases in an aluminium cast iron structure and thereby improve the production process. V and Ti additions to aluminium cast iron allow the development of FeAl - VC or TiC alloys. In particular, V or Ti contents above 5 wt.% were found to totally eliminate the presence of Al4C3. In addition, preliminary work indicates that the alloy with the FeAl - VC or TiC structure reveals high oxidation resistance. The introduction of 5 wt.% chromium to aluminium cast iron strengthened the Al4C3 precipitate. Thus, the resultant alloy can be considered an intermetallic FeAl matrix strengthened by VC and TiC or modified Al4C3 reinforcements.
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Abstract

The present research was conducted on thin-walled castings with 5 mm wall thicknesses. This study addresses the effect of the influence of different master alloys, namely: (1) Al-5%Ti-1%B, (2) Al-5%Ti and (3) Al-3%B, respectively on the structure and the degree of undercooling (ΔTα = Tα-Tmin, where Tα - the equilibrium solidification temperature, Tmin - the minimum temperature at the beginning of α(Al) solidification) of an Al-Cu alloy. The process of fading has been investigated at different times spent on the refinement treatment ie. from 3, 20, 45 and 90 minutes respectively, from the dissolution of master alloys. A thermal analysis was performed (using a type-S thermocouple) to determine cooling curves. The degree of undercooling and recalescence were determined from cooling and solidification curves, whereas macrostructure characteristics were conducted based on a metallographic examination. The fading effect of the refinement of the primary structure is accompanied by a significant change in the number (dimension) of primary grains, which is strongly correlated to solidification parameters, determined by thermal analysis. In addition to that, the analysis of grain refinement stability has been shown with relation to different grain refinements and initial titanium concentration in Al-Cu base alloy. Finally, it has been shown that the refinement process of the primary structure is unstable and requires strict metallurgical control.
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Abstract

Metal alloys with matrix based on an Fe-Al system are generally considered materials for high-temperature applications. Their main advantages are compact crystallographic structure, long-range ordering and structural stability at high temperatures. These materials are based on an intermetallic phase of FeAl or Fe3Al, which is stable in the range from room temperature up to the melting point of 1240°C. Their application at high temperatures is also beneficial because of the low cost of production, very good resistance to oxidation and corrosion, and high mechanical strength. The casting alloy the structure of which includes the FeAl phase is, among others, highaluminium cast iron. This study has been devoted to the determination of the effect of vanadium and titanium on the transformation of the high-aluminium cast iron structure into an in-situ FeAl-VC composite.
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Abstract

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.
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Abstract

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, Mg17Al12 and a solid solution of Mg in Al. When the temperature of the melt and the mould was lower (variant 1 – 670o C and 310 o ; variant 2 – 680o C and 310o C, respectively) the unreacted thin layer of aluminium was observed in the outer zone. Applying higher temperatures of the melt (685o C) and the mould (325o C) 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.
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Abstract

Al-Mas‘ūdī, a 10th century Arab traveller and writer spoke of a pagan custom present among the Slavs and the Rūs living in the Khazar capital, Ātil. Namely the posthumous marriage of an unmarried man. Another Arab author, Ibn Fadlān, witnessed and described in detail a burial ceremony of a Rūs chieftain, which had many elements of a wedding ritual. The two testimonies can be easily associated together. The practice of posthumously marrying an unmarried person has been present in Slavic culture for centuries. Even now some of its aspects can still be observed among Slavs, including Poles, although their true significance has long been forgotten.
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Abstract

In this study, metal matrix composite materials containing melt-spun Al-20Si-5Fe alloys and boron carbide was produced by high energy ball milling and then hot pressing at 200 MPa pressure and 450°C. Mechanical and microstructural characterizations were performed by using an optical microscopy, X-Ray diffractometer, and dynamic microhardness tester. It was observed that boron carbide particles were homogenously distributed in the microstructure and values of microhardness and elastic modules were averagely 830 MPa and 42 GPa, respectively.
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Abstract

The scope of this work is to investigate the precipitation of two Al-Mg-Si alloys with and without Cu and excess Si by using the differential scanning calorimetry (DSC), transmission electron microscopic (TEM), Vickers hardness measurement and X-ray diffraction. The analysis of the DSC curves found that the excess Si accelerate the precipitation and the alloy contain the excess Si and small addition of copper has higher aging-hardness than that of free alloy (without excess Si and Cu) at the same heat treatment condition. The sufficient holding time for the precipitation of the β'' phase was estimated to be 6 hours for the alloy aged at 100°C and 10 hours for the alloy aged at 180°C. The low Copper containing Al-Mg-Si alloy gives rise to the forming a finer distribution of β (Mg2Si) precipitates which increases the hardness of the alloy. In order to know more about the precipitation reactions, concern the peaks on the DSC curve transmission electron microscopy observation were made on samples annealed at temperatures (250°C, 290°C and 400°C) just above the corresponding peaks of the three phases β'', β' and β respectively.
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