Nanoobjects microscopy

Effects of Magnetodynamic Treatment on the Structure and Properties of Cast Al-Si-Cu Alloys
Berezina A.L.1, Monastyrska T.O.1, O.A. Molebny1, Fikssen V.M.2
1 G.V. Kurdyumov Institute for Metal Physics of the NAS of Ukraine, Vernadsky Blvd. 36, Kyiv-142, 03680, Ukraine 
E-mail: monast@imp.kiev.ua
2 Physico-Technical Institute of Metals and Alloys of the NAS of Ukraine, Vernadsky Blvd. 34/1, Kyiv-142, 03680, Ukraine

The widespread use of Al-Si alloys with high silicon content is due to their good mechanical and technological properties: low coefficient of linear expansion, high modulus, wear resistance and heat resistance [1, 2]. But low strength, ductility, machinability – these are disadvantages of those alloys. They are caused by the presence of coarse primary silicon in the matrix. Of great interest is to improve the technological characteristics and performances of the alloys and to induce the necessary properties. The primary task of research was to study the effect of  melt treatment in the magnetodynamic installation MDH-6A [3, 4], which has been developed by Physico-Technical Institute of Metals and Alloys of the NAS of Ukraine, and to study the effect of subsequent heat treatments that provide alloy hardening during  solid state aging.
Нypereutectic Al-Si alloys were chosen for investigation. It was shown that the treatment of the melt in the magnetodynamic installation using the ARSAL refining flux and properly chosen heat treatment of the solidificated alloys allows one to refine primary silicon particles, reduce segregation of alloying elements, increase the supersaturation of solid solution, to enlarge the volume fraction of the nanoparticles formed during the ageing process. As a result, σB increases from 322 MPa in the initial state to 353 MPa, στ - from 280 MPa to 317 MPa and elongation δ increases from 0.78% to 1.55%.

1.	Kolobnev I.F. Heat resistance of cast aluminum alloys // Metallurgia, Moscow.-1973.- P. 320. (In Russian).
2.	Stroganov G.B. High strength aluminium alloys // Metallurgia, Moscow.-1985.- p. 216. (In Russian).
3.	Polishchuk V., Horn R., Tsin M., Dubodelov V., Pogorsky V., Trefniak V. Magnetodynamic pumps for liquid metals // Kyiv, Naukova dumka. -1989. - P. 256. (in Russian).
4.	Fixsen W., Ohm L., Trefnjak V. Electro-magnetic low-pressure casting of Al alloys // Casting Plant &Technology International. -2007. - N 2. - Р. 38-39.