Željko Alar

Prof. Dr. Željko Alar


Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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8 July 2021 in Coatings
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Journal Article
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Danko ĆorićDanko Ćorić
Danko Ćorić
Mateja ŠnajdarMateja Šnajdar
Mateja Šnajdar
MSMatija Sakoman
Matija Sakoman
ŽAŽeljko Alar
Željko Alar
The development of cemented carbides nowadays is aimed at the application and sintering of ultrafine and nano-sized powders for the production of a variety of components where excellent mechanical properties and high wear resistance are required for use in high temperature and corrosive environment conditions. The most efficient way of increasing the tribological properties along with achieving high corrosion resistance is coating. Using surface processes (modification and/or coating), it is possible to form a surface layer/base material system with properties that can meet modern expectations with acceptable production costs. Three coating systems were developed on WC cemented carbides substrate with the addition of 10 wt.% Co using the plasma-assisted chemical vapor deposition (PACVD) method: single-layer TiN coating, harder multilayer gradient TiCN coating composed of TiN and TiCN layers, and the hardest multilayer TiBN coating composed of TiN and TiB2. Physical and mechanical properties of coated and uncoated samples were investigated by means of quantitative depth profile (QDP) analysis, nanoindentation, surface layer characterization (XRD analysis), and coating adhesion evaluation using the scratch test. The results confirm the possibility of obtaining nanostructured cemented carbides of homogeneous structure without structural defects such as eta phase or unbound carbon providing increase in hardness and fracture toughness. The lowest adhesion was detected for the single-layer TiN coating, while coatings with a complex architecture (TiCN, TiBN) showed improved adhesion.

28 April 2025 in Materials
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Journal Article
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DPDaniel Pustički
Daniel Pustički
ŽAŽeljko Alar
Željko Alar
ZBZvonimir Bandov
Zvonimir Bandov
The advancement of additive manufacturing (AM) technologies, particularly laser powder bed fusion (LPBF), has enabled the production of complex components with enhanced mechanical properties and shorter lead times compared to conventional manufacturing processes. This study focuses on the characterization of maraging steel (EOS MS1) fabricated by LPBF technology using an EOS M 290 system. Three material groups were investigated: a conventionally manufactured tool steel (95MnWCr5) serving as a reference, LPBF-produced maraging steel in the as-built condition, and LPBF-produced maraging steel subjected to post-processing heat treatment. The samples were thoroughly examined using optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES), electrochemical corrosion analyses in a 3.5% NaCl solution, and Vickers microhardness measurements. Electrochemical tests revealed that heat-treated LPBF maraging steel samples exhibited slightly increased corrosion current densities relative to their as-built counterparts, attributed to the formation of Ti-rich and Ni-rich precipitates during aging, creating localized microgalvanic cells. Despite the increased corrosion susceptibility, hardness measurements clearly demonstrated enhanced hardness and mechanical properties in heat-treated samples compared to the as-built state and conventional tool steel reference. The findings underscore the importance of optimized LPBF parameters and controlled post-processing heat treatments in balancing mechanical performance and corrosion resistance. Consequently, LPBF-produced maraging steels hold considerable promise for tooling and industrial applications where high strength, dimensional stability, and acceptable corrosion behavior are required.

20 June 2023 in Metals
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Journal Article
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Tomislav RodingerTomislav Rodinger
Tomislav Rodinger
Danko ĆorićDanko Ćorić
Danko Ćorić
ŽAŽeljko Alar
Željko Alar
The choice of foaming agent and its mass fraction significantly affect the size and number of metal foam cells. The powder metallurgy process was used to produce aluminium foams with the addition of various foaming agents: titanium hydride (TiH2) and calcium carbonate (CaCO3). TiH2 was added in an amount of 0.4 wt.%, while the quantity of CaCO3 varied between 3 and 5 wt.%. The produced foams, with approximately the same degree of porosity, were scanned using a non-destructive computed tomography method. The number, size, equivalent diameter, sphericity, and compactness of cells were analysed on the obtained three-dimensional models. The results showed that foams foamed with TiH2 have much larger cells compared to CaCO3 agent. By considering the influence of CaCO3 fraction on the morphology of aluminium foam, it follows that a smaller quantity of CaCO3 (3 wt.%) provides a macrostructure with smaller cells. Samples with five wt.% CaCO3 contain slightly larger cells but are still much smaller than foams with TiH2 foaming agent at the same degree of porosity. The sphericity and compactness indicate that TiH2 foaming agent forms cells of a more regular shape compared to CaCO3 agent.