Livarski vestnik 56 / 2009 number. 2
Niko Rozman, Franc Zupanič, Mitja Petrič, Jože Medved, Primož Mrvar
Die Casting of Al-Mn-Be-Cu Alloy
Grega Klančnik, Jožef Medved, Primož Mrvar, Vončina Maja
Influence of Recycling on Solidification and Development of Microstructure in AlSi9Cu3 Alloy
Jaromir Roučka, Aleš Sláma, V. Kaňa, J. Makalouš, Radovan Koplík
Filtration of Aluminium Alloy
Niko Rozman, Franc Zupanič, Mitja Petrič, Jože Medved, Primož Mrvar
Die Casting of Al-Mn-Be-Cu Alloy
Abstract
New Al-Mn-Be-Cu alloy was developed, forming icosahedral quasi-crystalline phase (i-phase) at moderate cooling rates. Test alloys were cast into moulds of varying size and shape. The aim of the examination was to determine the effect of the mould size and shape on the formation of microstructure and consequently also on the alloy hardness. Microstructure analyses were carried out using scanning electron microscopy and energy dispersive X-ray spectroscopy.
The following conclusions were made:
The icosahedral quasicrystalline phase is formed at moderate cooling rates, i.e. by solidification in a copper mould. When sample was cast into mould with rectangular shape (1 mm) only quasi-crystalline phase without detrimental Al-Mn intermetallic phases was present in the Al-rich solid solution. The Al-Mn phases were formed only in the centre of the 4 mm mould. The quasi-crystalline phase was also present in the centre of the 6 mm mould while it was not found in the 8 mm mould.
The alloys contained Al-rich solid solution (Al), and the Al2Cu and Al10Mn3 intermetallic phases next to the icosahedral quasi-crystalline phase. The i-phase was present as primary phase having shapes of facetted particles (pentagonal dodecahedron) and dendrites, but also as a constituent of the binary (Al + i-phase) eutectic.
Cooling rate had a profound effect on the formation of microstructure and the size of microstructural constituents therefore it was not easy to obtain uniform microstructure.
The presence of i-phase in the alloy and its distribution in the microstructure caused a high hardening effect in the material. Despite of these promising results, further work will be needed to manufacture complex thin-walled castings. The focus in further examinations will be directed into experimental determination of cooling curves during the casting process into various copper moulds and to casting simulations.
The following conclusions were made:
The icosahedral quasicrystalline phase is formed at moderate cooling rates, i.e. by solidification in a copper mould. When sample was cast into mould with rectangular shape (1 mm) only quasi-crystalline phase without detrimental Al-Mn intermetallic phases was present in the Al-rich solid solution. The Al-Mn phases were formed only in the centre of the 4 mm mould. The quasi-crystalline phase was also present in the centre of the 6 mm mould while it was not found in the 8 mm mould.
The alloys contained Al-rich solid solution (Al), and the Al2Cu and Al10Mn3 intermetallic phases next to the icosahedral quasi-crystalline phase. The i-phase was present as primary phase having shapes of facetted particles (pentagonal dodecahedron) and dendrites, but also as a constituent of the binary (Al + i-phase) eutectic.
Cooling rate had a profound effect on the formation of microstructure and the size of microstructural constituents therefore it was not easy to obtain uniform microstructure.
The presence of i-phase in the alloy and its distribution in the microstructure caused a high hardening effect in the material. Despite of these promising results, further work will be needed to manufacture complex thin-walled castings. The focus in further examinations will be directed into experimental determination of cooling curves during the casting process into various copper moulds and to casting simulations.
Grega Klančnik, Jožef Medved, Primož Mrvar, Vončina Maja
Influence of Recycling on Solidification and Development of Microstructure in AlSi9Cu3 Alloy
Abstract
In the car industry AlSi9Cu3aluminium alloy is well known also under the name 226 (DIN 1725 t 2:1986). This aluminium alloy has good casting properties and because of that it is devised for more complex car parts such as cylinder block castings. The AlSi9Cu3 aluminium alloy is recycled most often as scrap of various sizes and therefore an examination of influence of scrap specific surface was made. The quality of obtained melt was determined by the simple thermal analysis (ETA) with cooling curves. The influence of specific surface was reflected also in macro- and microstructures. Several methods were used for characterization: chemical analysis, simple thermal analysis (ETA), simultaneous thermal analysis (STA), thermodynamic simulation of equilibrium phases, and metallographic analysis.
Key words: AlSi9Cu3 alloy, recycling, thermal analysis, thermodynamics.
Key words: AlSi9Cu3 alloy, recycling, thermal analysis, thermodynamics.
Jaromir Roučka, Aleš Sláma, V. Kaňa, J. Makalouš, Radovan Koplík
Filtration of Aluminium Alloys
Abstract
Abstract
Filtration effectiveness of different types of filter was tested in the process of casting aluminium alloy AlSi9Cu3. In the tests, 2-ply corrugated fibre filters Gephal (manufacturer Hüttenes-Albertus), foam filters of Al2O3- and SiC-based ceramics (densities of 20 and 30 ppi) as well as pressed filters with straight openings, of different densities and different opening sizes, made of Pyrostat ceramic, were used. During testing, the alloy was poured through a metallic test mould, which represented the gating system with placed filter. After passing through the mould, the alloy flowed freely into a collecting crucible placed on a weighing facility. Via continuous weighing for the period of pouring the waveform of the total mass of metal poured and the time dependence of mass pouring velocity were followed. These relations were evaluated and used to assess the rate of flow, the effect of filter on pouring capacity, and the magnitude of hydraulic resistance of the filters. The captured inclusions were examined metallographically and the decisive filtration mechanisms were assessed. It was established that in all the types of filter the decisive mechanism of the separation of inclusions was the cake filtration. Deep filtration occurs in the case of foam and fibre filters; deep filtration in filters with straight openings is negligible.
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