Search

Your search keyword '"Ivana Kirkovska"' showing total 3 results
Start Over Author "Ivana Kirkovska"
3 results on '"Ivana Kirkovska"'

1. The Influence of the Third Element on Nano-Mechanical Properties of Iron Borides FeB and Fe2B Formed in Fe-B-X (X = C, Cr, Mn, V, W, Mn + V) Alloys

Author

Ivana Kirkovska, Viera Homolová, Ivan Petryshynets, and Tamás Csanádi

Subjects
iron borides, hardness, modulus, nanoindentation, indentation size effect, Fe-B-X (X = C, Cr, Mn, V, W, V + Mn) alloys, Technology, Electrical engineering. Electronics. Nuclear engineering, TK1-9971, Engineering (General). Civil engineering (General), TA1-2040, Microscopy, QH201-278.5, Descriptive and experimental mechanics, QC120-168.85
Abstract

In this study, the influence of alloying elements on the mechanical properties of iron borides FeB and Fe2B formed in Fe-B-X (X = C, Cr, Mn, V, W, Mn + V) alloys were evaluated using instrumented indentation measurement. The microstructural characterization of the alloys was performed by means of X-ray diffraction and scanning electron microscope equipped with an energy dispersive X-ray analyzer. The fraction of the phases present in the alloys was determined either by the lever rule or by image analysis. The hardest and stiffest FeB formed in Fe-B-X (X = C, Cr, Mn) alloys was observed in the Fe-B-Cr alloys, where indentation hardness of HIT = 26.9 ± 1.4 GPa and indentation modulus of EIT = 486 ± 22 GPa were determined. The highest hardness of Fe2B was determined in the presence of tungsten as an alloying element, HIT = 20.8 ± 0.9 GPa. The lowest indentation hardness is measured in manganese alloyed FeB and Fe2B. In both FeB and Fe2B, an indentation size effect was observed, showing a decrease of hardness with increasing indentation depth.

Published
2020
Full Text
View/download PDF

2. Experimental Study and Thermodynamic Modeling of B-Fe-W System

Author

Ivana Kirkovska, Adéla Zemanová, Ondřej Zobač, and Viera Homolová

Subjects
Ternary numeral system, Materials science, Scanning electron microscope, Metals and Alloys, Analytical chemistry, chemistry.chemical_element, Tungsten, Condensed Matter Physics, Differential scanning calorimetry, chemistry, Phase (matter), Materials Chemistry, CALPHAD, Powder diffraction, Solid solution
Abstract

The present study investigates experimentally phase equilibria relations in the B-Fe-W ternary system. For the experimental study, B-Fe-W alloys were produced by arc-melting. These alloys were equilibrated using long-term annealing for 2000 h and 4224 h at temperatures of 1050 and 677 °C, respectively. The alloys were characterized by scanning electron microscopy coupled with energy dispersive x-ray spectroscopy, x-ray powder diffraction analysis, and differential scanning calorimetry. Based on the experimental results, the B-Fe-W system was modeled using the CALPHAD method. Herein, boron was modeled interstitially in the solid solutions of iron and tungsten. Also, in this study, the volume phase fractions for selected B-Fe-W alloys were determined using an image analysis technique.

Published
2021

3. Nanomechanical Characterization of Iron Borides in Fe-Mn-B Ternary Alloys

Author

Viera Homolová, Ivana Kirkovska, Lucia Čiripová, and Ivan Petryshynets

Subjects
010302 applied physics, Radiation, Materials science, 02 engineering and technology, Nanoindentation, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Indentation hardness, Characterization (materials science), Chemical engineering, 0103 physical sciences, General Materials Science, 0210 nano-technology, Ternary operation
Abstract

Nanomechanical properties of iron borides, FeB and Fe2B were studied in Fe-Mn-B ternary alloys. The alloys were produced by arc melting method using high purity powders, which were subsequently annealed at temperature of 873 K and 1223 K, until fully equilibrated for a time period of 2160 hours and 1440 hours, respectively. Based on results obtained from experimental study and thermodynamic modeling of Fe-Mn-B system the solubility of Mn in these borides was determined. For the purpose of this study the influence of heat treatment temperature, as well as, the solubility of Mn in these borides on their nanomechanical properties is investigated. Nanomechanical properties, including determination of indentation modulus and hardness were measured using nanoindentation testing machine equipped with Berkovich type diamond indenter. The indentation process was carried out using an indentation depth controlled method, to a maximum depth of 500 nm.

Published
2020

Catalog

Books, media, physical & digital resources
See catalog results