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Effect of Si, B, Al2O3 and ZrO2 nano-modifiers on the structural and mechanical properties of Fe + 0.5% C alloy

Karunakaran G., Van Minh N., Konyukhov Y., Kolesnikov E., Venkatesh M., Kumar G. S., Gusev A., Kuznetsov D.

Archives of Civil and Mechanical Engineering

2017

Vol. 17, no. 3

669--676

In the present study, we have incorporated different nanoparticles such as silicon (Si), boron (B), alumina (Al2O3) and zirconium (ZrO2) as modifiers in Fe + 0.5% C alloy to evaluate its influence in it. The properties such as hardness, volume shrinkage/swelling, flexural strength, relative density and fracture analysis of Fe + 0.5% C alloys with and without nanomodifier are also analyzed. The obtained result reveals that incorporation of Si, and B nanoparticles greatly improves the hardness, volume shrinkage/swelling, flexural strength, and relative density of Fe + 0.5% C alloys by increasing grain numbers and reducing the porosity. The SEM analysis of fractured samples clearly showed the involvement of nanoparticles during the alloy formation. Si and B nanoparticles completely entered into the grain and leads to the improvement of structural and mechanical properties of the alloy. However, Al2O3 and ZrO2 nanoparticles are observed on the surface of the grain, which clearly indicates that it does not take part in the alloy formation, which leads to affect its structural and mechanical properties. Thus, this study enlightens the use of nano Si and B as a modifier to enhance the structural and mechanical properties of Fe + 0.5% C alloy via powder metallurgy.

The kinetics of phase transformations of undercooled austenite of the Mn-Ni iron based model alloy

Rożniata E., Dziurka R., Pacyna J.

Journal of Achievements in Materials and Manufacturing Engineering

2011

Vol. 49, nr 2

188--192

Purpose: Present work corresponds to the research on the kinetics of phase transformations of undercooled austenite of Mn-Ni iron based model alloy. The kinetics of phase transformations of undercooled austenite of investigated alloy was presented on CCT diagram (continuous cooling transformation). Also the methodology of a dilatometric samples preparation and the method of the critical points determination were described. Design/methodology/approach: The austenitising temperature was defined in a standard way i.e. 30-50°C higher than Ac3 temperature for model alloy. A technique of full annealing was proposed for the model alloy. The CCT diagrams were made on the basis of dilatograms recorded for samples cooled at various rates. The microstructure of each dilatometric sample was photographed after its cooling to the room temperature and the hardness of the samples was measured. Findings: The test material was a Mn-Ni hypoeutectoid iron based alloy. The microstructure of test Mn-Ni alloy on CCT diagram changes depending on the cooling rate. At the cooling rates of 10°C/s and 5°C/s there is ferrite in Widmannstatten structure present in the structure of tested alloy. Research limitations/implications: The new Mn-Ni iron based model alloy and a new CCT diagram. Practical implications: The paper contains a description of one from a group of iron based model alloys with 0.35-0.40% carbon content. According to PN-EN 10027 standard this steel should have a symbol 38MnNi6-4. Originality/value: The new Mn-Ni iron based model alloy.