Characterisation of Solidified Microstructure of Solid Solutions
Andräs ROÖSZ, Zoltän GÄCSI, Jenö KOVÄCS
‘ton formediun) Physical Metallurgy Department, Materials Science Institute, University of Miskolc
9 Inyestigate pr H-3515 Miskolc-Egyetemvaros, Hungary
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mens | gy Abstract
Wai First this paper gives a summary of the solidified structures of solid solutions, the solidification
of suc metho s, and the investigation possibilities of solidified structures. Afterwards through an example
oe moi the influences of the solid/liquid interface velocity on the dendrite morphology in the case of
i steady-state unidirectional solidification are shown.
Al-4wt%Cu alloy was used as testing material. The temperature gradient at the solid/liquid interface
was 1500 K/m and the moving velocities of samples were 5x10, 2x10* and 8x10“ m/s. The
purpose of experiments was the accurate numerical determination of the typical parameters of the
dendritic structure. The amount of the second phase (AL Cu), as well as the primary, the secondary
Press, New Yok- and the tertiary dendrite arm spacing were measured. For quantitative characterisation the image
analyser equipment type Quantimet 500 Image Workstation was used. The measured values were
rapky at a third studied as a function of the solid/liquid interface velocities.
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€ Phase cnrası] Introduction
+ Merle and Peix'
The most part of alloys used in practice is solid solutions type, which means that the alloys consist
ation of internal of only solid solution after equilibrium solidification (Le. aluminium and copper alloys, steels). The
v. Acta Met vol properties of the alloys, besides their composition, are determined by their structure. The structure
developed during solidification is influenced by the solidification parameters (G: temperature
studied by x-ray gradient, v: solid/liquid front velocity). The solidification parameters are not constant in practical
¢ Euromat 99 technologies (form and continuos casting) and generally they are not measurable. Therefore, the
3-73. specimens produced by these technologies are unsuitable to determine the function between
cn 11. 1997. structure and solidification parameters. Different experimental solidification methods have been
ıe mechanisnsof developed to investigate the solidification processes by using controlled solidification parameters.
9’ conference I The parameters of solidified structures can be investigated by light and electron microscopy, X-ray
diffraction and microanalyser methods. In this lecture the structures developed during solidification
» Mel and Pet and the solidification methods carried out by controlled solidification parameters will be shown
briefly. Afterwards determination of the parameters of solidified structures will be presented in
detail. Finally, the determination of the parameters of solidified structures will be demonstrated
through the example of steady-state unidirectional solidified Al-4wt% Cu alloy.
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