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Number of results: 15
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Abstract

An attempt was made to determine phase composition of commercial aluminium alloys using X-ray diffraction. Samples for phase composition analysis were selected from the group of aluminium alloys covered by the EN 573-3:2013 standard [1]. Representative samples were taken from eight groups of alloys with different chemical composition (at least one sample from each group). The diffraction intensity was measured with a standard X-ray diffractometer in Bragg-Brentano geometry in a way that allowed identification of the weakest diffraction peaks. As a results of the performed research it has been shown that X-ray phase analysis can be used to identify the matrix of aluminium alloys, Si and crystalline intermetallic phases such as Mg2Si, Al93.38Cu6.02Fe24Si16.27, Al4.01MnSi0.74, MgZn2, Al17(Fe3.2Mn0.8)Si2, Al65Cu20Fe15, and Cu3Mn2Al. The detectability limit of the above-mentioned phases is better than 0.5%. The research has also shown that X-ray phase analysis is applicable in the investigation of phase transformations taking place in aluminium alloys.
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Abstract

The paper presents the results of the electrodeposition of nickel composite coatings reinforced with the ceramic SiC particles. A Watts type galvanic bath modified with various organic additives was used. These additives were: 2-sulfobenzoic acid imide (LSA), dioctyl sulfosuccinate sodium salt (DSS), sodium dodecyl sulfate (SDS), tris (hydroxymethyl) aminomethane (THAM) and hexamethyldisilizane (HMDS). The nickel composite coating was electrodeposited on a 2xxx aluminum alloy series substrate (EN-AW 2017) with zinc interlayer. Studies concerned the effect of the applied organic additives on properties of composite coatings such as: microstructure, microhardness, adhesion to the substrate, corrosion resistance and roughness. The structure of the coatings was assessed by scanning electron microscopy and light microscopy. Based on the studies of zeta potential it was found that the bath modification had a significant impact on the amount of the ceramic phase embedded in metal matrix. The tests conducted in a model 0.01 M KCl solution were not fully representative of the true behavior of particles in a Watts bath.
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Abstract

In the aluminium alloy family, Al-Zn materials with non-standard chemical composition containing Mg and Cu are a new group of alloys, mainly owing to their high strength properties. Proper choice of alloying elements, and of the method of molten metal treatment and casting enable further shaping of the properties. One of the modern methods to produce materials with submicron structure is a method of Rapid Solidification. The ribbon cast in a melt spinning device is an intermediate product for further plastic working. Using the technique of Rapid Solidification it is not possible to directly produce a solid structural material of the required shape and length. Therefore, the ribbon of an ultrafine grain or nanometric structure must be subjected to the operations of fragmentation, compaction, consolidation and hot extrusion. In this article the authors focussed their attention on the technological aspect of the above mentioned process and described successive stages of the fabrication of an AlZn9Mg2.5Cu1.8 alloy of ultrafine grain structure designated for further plastic working, which enables making extruded rods or elements shaped by the die forging technology. Studies described in the article were performed under variable parameters determined experimentally in the course of the alloy manufacturing process, including casting by RS and subsequent fragmentation.
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Abstract

Contemporary materials engineering requires the use of materials characterised by high mechanical properties, as these precisely properties determine the choice of material for parts of machinery and equipment. Owing to these properties it is possible to reduce the weight and, consequently, the consumption of both material and energy. Trying to meet these expectations, the designers are increasingly looking for solutions in the application of magnesium alloys as materials offering a very beneficial strength-to-weight ratio. However, besides alloying elements, the properties are to a great extent shaped by the solidification conditions and related structure. The process of structure formation depends on the choice of casting method forced by the specific properties of casting or by the specific intended use of final product. The article presents a comparison of AZ91 magnesium alloys processed by different casting technologies. A short characteristic was offered for materials processed by the traditional semi-continuous casting process, which uses the solidification rates comprised in a range of 5 - 20⁰C/s, and for materials made in the process of Rapid Solidification, where the solidification rate can reach 106 ⁰C/s. As a result of the casting process, a feedstock in the form of billets and thin strips was obtained and was subjected next to the process of plastic forming. The article presents the results of structural analysis of the final product. The mechanical properties of the ø7 mm extruded rods were also evaluated and compared.
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Abstract

The effect of plastic deformation process on the dissolution rate of biocompatible Mg alloys was investigated. Two biocompatible MgLi1Ca0,2Zn1 and MgLi1Ca1Zn1 alloys were selected for the study. The alloys were deformed on a 100T press at a temperature of 350°C by conventional extrusion and by the equal channel angular extrusion process (ECAE). The grain size analysis showed a high degree of the grain refinement from approximately 110 mm in the initial state to 2.8 mm after the 3rd pass of the ECAE process. Compared to as-cast state, the degree of strengthening has increased after plastic forming. The results of biodegradation tests have shown a significant increase in corrosion rate after both conventional extrusion and ECAE, although after subsequent ECAE passes, this rate was observed to slightly decrease in the MgLi1Ca1Zn1 alloy. Based on the results of macro- and microstructure examinations, the corrosion progress in samples after the extrusion process was described.
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