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Crystallization Behavior and Properties of Hypereutectic Al-Si Alloys with Different Iron Content

Deev V., Prusov E., Prikhodko O., Ri E., Kutsenko A., Smetanyuk S.

Archives of Foundry Engineering

2020

Vol. 20, iss. 4

101--107

Understanding the influence of iron impurity on the formation of the structure and the properties of hypereutectic aluminum-silicon alloys are important for achieving the required quality of castings, especially those obtained from secondary materials. In the present work, the influence of different iron contents (0.3, 1.1, and 2.0 wt.%) on the crystallization process, microstructure and mechanical properties of the Al-15% Si alloy was studied. It is shown that the presence of iron impurity in the Al-15% Si alloy leads to increasing the eutectic crystallization time from 6.2 to 7.6 s at increasing the iron content from 0.3 wt.% to 1.1 wt.%, changing the structure of the alloy eutectic in the solid state. The primary silicon and β-Al5SiFe phase coexist in the structure of the Al-15% Si alloys at a temperature below 575°C in the range of iron concentrations from 0 to 2 wt.% in equilibrium conditions. In the experimental alloys structure, the primary crystals of the β-phase were metallographically detected only in the alloys containing 1.1 and 2 wt.% of iron impurity. Increase of the iron content up to 2 wt.% significantly reduces the mechanical properties of the Al-15% Si alloy due to the formation of large platelet-like inclusions of β-Al5SiFe phase.

Non-linear optical properties of epoxy-based polymers with covalently attache chromophores and metallic complexes

Borshch A., Brodyn M., Lyakhovetsky V., Kutsenko A., Maloletov S.

Materials Science

2002

Vol. 20, No. 4

29-48

Non-linearl refraction and absorption in polymer structures based upon diglicidylether of bisphenol A has been studied. The polymers contain organo-metallic complex of nickel(II) NiL(ClO4) 2- or 4-amino-azobenzene as non-linear optically active side groups covalently attached at each monomer unit. The studies have been carried out by polarization technique together with a real time pump and probe technique, dynamic holography and Z-scan. The materials were shown to exhibit fast non-linear response (relaxation time is about 20 ns) together with slow one (relaxation time of the order of tens of hours). This makes it possible to record fast- and long-lived (quasi-stationary) phase holograms. The analysis of possible mechanisms for the polymer refractive index non-linear response in the time range from 10-8 to 105 is presented. In particular, the role of electron polarizability, thermal excitation of the polymer, orientation of the chromophore molecules, and trans-cis isomerization processes are discussed.