Modifying additives complex effect on AK12 alloy structure and mechanical properties

Аuthors

Shlyaptseva A. D.^1*, Petrov I. A.^1**, Ryakhovskii A. P.^1***, Moiseev V. S.^2****

1. Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
2. ,

*e-mail: dimash881@yandex.ru
**e-mail: Lumen-2007g@mail.ru
***e-mail: fpkp@mai.ru
****e-mail: castingtlp@mati.ru

Abstract

The paper presents the study of the effect on AK12 alloy structure and mechanical properties while subjecting its melt to complex modifying treatment with carbon-bearing Freon12 gas and salt compounds.

Based on earlier obtained results, we sel ected K₂TiF₆, BaCO₃ salt compounds and carbon (graphite) as modifying compounds. KA12 alloy processing with the sel ected compounds was performed both without and with its melt blowing-down by the above mentioned gas.

Mechanical tests results and microstructure analysis revealed that the Freon-12 blowing-down makes modifying impact on AK12 alloy. The highest mechanical properties, and refining of ?-solid solution dendrites and refining of silicon particles in an eutectic is observed at simultaneous treatment of an AK12 alloy by the modifying salts (BaCO₃ + K₂TiF₆ + C) together with Freon. The strength of the alloy equals to176 MPa, and relative elongation equals to 9,40%.

Besides, the Freon blowing-down increases the modifying effect for the majority of considered flux compounds. The alloy AK12 treatment with Freon and salts (BaCO₃ + K₂TiF₆) is most perspective, compared to the alloy modified only by salts (BaCO₃ + K₂TiF₆). The strength increased fr om 162 to 188 MPa, and elongation - from 7,70 to 9,01%.

Based on thermograms obtained while the melt treatment, surface morphology data and elementary composition of AK12 alloy treated with test compounds, we made a conclusion on the presence of carbon-bearing disperse particles similar in composition to aluminum and titanium carbides in threated with salt compounds (BaCO₃ + K₂TiF₆) and Freon alloy. Those formed carbides can be additional crystallization centers in the melt due to dimensional and structural resemblance with aluminum crystal lattice.

Analysis of the results of the carried on research revealed the perspective of carbon-bearing materials, and Freon 12 in particular, implementation as aluminum-silicon alloy modifiers.

Keywords:

silumins modification with freon, effect on aluminum alloys mechanical propertiesf

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