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1

Forging and rolling of magnesium alloy AZ61

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Greger M. , Kocich R. , Čižek L.

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tom Vol. 20, nr 1-2

447-450

EN

Purpose: The paper summarises results of experiments aimed at development of structure of modified alloy AZ61 at hot deformation. Design/methodology/approach: Deformation behaviour of alloy was verified at the temperature of 420 degrees centigrade by rolling at 380 degrees centigrade by forging, respectively. Findings: Magnesium alloy AZ 61 have hexagonal structure and their forming is at room temperatures very difficult, that's why big plastic deformations are carried out in hot condition. After plastic deformations was obtained that original grain size decreased 15 times. Research limitations/implications: This paper provide data about magnitude of deformation, strain rate and temperature of forming at different techniques of plastic deformation. It was aimed to determine the conditions for non problem rolling and forging respectively. Practical implications: Initial structure was as cast and after heat treatment T4. Heat treatment appeared much better for forming as well as forging than rolling because of state of stress. Originality/value: Role of beta phase (Mg17Al12) in these alloys at plastic forming is very important, such that how it was obtained, best final properties of AZ 61 alloy supports very fine particles, distributed into Mg matrix. Next a relevant information is that multi stage forming process is much better in comparison with a big single reduction.

2

Heat treatment impact on the structure of die-cast magnesium alloys

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Dobrzański L. A. , Tański T. , Čižek L.

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tom Vol. 20, nr 1-2

431-434

EN

Purpose: In the following paper there have been the structure and properties of the MCMgAl6Zn1 magnesium cast alloy as-cast state and after heat treatment presented. Design/methodology/approach: A casting cycle of alloys has been carried out in an introduction crucible furnace using a protective salt bath Flux 12 equipped with two ceramic filters at the melting temperature of 750 plmin 10 degrees centigrade, suitable for the manufactured material. The following results concern light and scanning microscopy, X-ray qualitative and quantitative microanalysis. Findings: The results of the EDS chemical composition analysis confirm the presence of magnesium, aluminium, manganese, and zinc, constituting the structure of alpha solid solution with Mg17Al12 placed mainly on the grain order in the form of plates, also the phase AlMnFe with irregular shape, occurred often in the shape of blocks or needles and the Laves phase Mg2Si. Research limitations/implications: According to the alloys characteristics, the applied cooling rate and alloy additions seems to be good compromise for mechanical properties and microstructures, nevertheless further tests should be carried out in order to examine different cooling rates and parameters of solution treatment process and aging process. Practical implications: A desire to create as light vehicle constructions as possible and connected with it low fuel consumption have made it possible to make use of magnesium alloys as a constructional material in automotive industry. Originality/value: The undertaken examinations aim at defining the influence of a chemical composition and precipitation processes on the structure and casting magnesium alloy properties in its as-cast state and after heat treatment with a different content of alloy components.

3

Hodnocení odolnosti proti abrazivnímu opotřebení

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Chalupa J. , Hubačková I. , Čižek L. , Król S.

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tom z. 57

167-170

4

Microstructure of MCMgAl12Zn1 magnesium alloy

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Dobrzański L. A. , Tański T. , Čižek L.

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2007

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tom Vol. 7, iss. 1

179-182

EN

In this paper is presented the structure of the cast magnesium alloys as cast state and after heat treatment cooled with different cooling rate, depending on the cooling medium (furnace, water, air). For investigations samples in shape of 250x150x25 mm plates were used. The structure have been study in the light microscope, scanning electron microscope equipped with an electron back scattering facility. The effects of the addition of Al on the microstructure were also studied. In the analysed alloys a structure of [alpha] solid solution and fragile phase [beta] (Mg_17Al_12) occurred mainly on grain borders as well as eutectic and phase with Mn, Fe and Si. Investigation are carried out for the reason of chemical composition influence and precipitation processes influence to the structure and mechanical properties of the magnesium cast alloys with different chemical composition in as cast alloys and after heat treatment.