Nanocomposites and nanomaterials
The effect of rapid quenching and composition of Al-TM, Al-TM-REM alloys on the formation of dispersed multicomponent (composite) particles 
A.L. Berezina1, O.A. Molebnyi1, V.M. Shyvaniuk1, V.I. Bondarchuk1, 
T.O. Monastyrska1, S.L. Polyvoda2
1 G.V. Kurdyumov Institute for Metal Physics of the NAS of Ukraine. 
Vernadsky Blvd. 36, Kyiv-142, 03680, Ukraine. 
E-mail: moleb@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 design of new-generation Al-based alloys requires a significant increase in the concentration of low-soluble transition metals (TM), rare-earth metals (REM) in solid aluminum and development of dispersing methods of trialuminides. 
Studies of the structural state of the alloys were carried out as a function of the Zr content (1%-9%). Al-3%Zr alloy was chosen as a basic one to study the dispersion patterns of refractory intermetallic compounds and formation of the supersaturated solid solutions during crystallization. The changes in the structural state of the basic alloy depending on the casting temperature (700-14000С), cooling rate (101-106deg/sec), and the nature of the target alloying were studied. The technology of intensive mixing of the melt and casting into a chill mold from  7000С provided a crystallization rate of 101deg/sec. Al3Zr intermetallides caused by crystallization form large particles with a size of up to 10μm and fine particles of size 2-3μm that uniformly distributed in the Al matrix with a 0.12 wt.% of Zr. The overheating of the melt to 1000°C and the crystallization rate of 103deg/sec causes increasing of Zr content in the matrix from 0.12 to 2.4%. In other words, an anomalously supersaturated solid solution is formed that is capable of dispersion hardening due to the nano-sized Al3Zr hardening particles precipitation. The use of Sc, Er micro-alloying in an amount of 0.05% impacts clustering processes in the liquid-solid region, completely eliminates the formation of large particles of d10μm, and contributes to the refining of primary intermetallic compounds to d1μm with a significant increase in their precipitation density. 
An increase of the cooling rate is accompanied with thermal diffusion processes, because of which the concentration gradient in Zr is established over the depth of the ribbon. At a rate of 106deg/sec, turbulent convection flows are formed, as well as a vortex structure with Al3Zr particles. The addition of 3-4% Mg to the alloy increases the melt viscosity, removes thermal diffusion processes, levels the concentration on the free and contact side and increases the degree of supersaturation of the solid solution.