Doina Rǎducanu

Dr. Doina Rǎducanu


Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

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

Representative Publications

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22 June 2021 in Materials
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ANANNA NOCIVIN
ANNA NOCIVIN
DRDoina Rǎducanu
Doina Rǎducanu
Bogdan Stefan VasileBogdan Stefan Vasile
Bogdan Stefan Vasile
CTCorneliu Trisca-Rusu
Corneliu Trisca-Rusu
ECElisabeta Mirela Cojocaru
Elisabeta Mirela Cojocaru
VCVasile Danut Cojocaru
Vasile Danut Cojocaru
The present paper analyzed the microstructural characteristics and the mechanical properties of a Ti–Nb–Zr–Fe–O alloy of β-Ti type obtained by combining severe plastic deformation (SPD), for which the total reduction was of εtot = 90%, with two variants of super-transus solution treatment (ST). The objective was to obtain a low Young’s modulus with sufficient high strength in purpose to use the alloy as a biomaterial for orthopedic implants. The microstructure analysis was conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) investigations. The analyzed mechanical properties reveal promising values for yield strength (YS) and ultimate tensile strength (UTS) of about 770 and 1100 MPa, respectively, with a low value of Young’s modulus of about 48–49 GPa. The conclusion is that satisfactory mechanical properties for this type of alloy can be obtained if considering a proper combination of SPD + ST parameters and a suitable content of β-stabilizing alloying elements, especially the Zr/Nb ratio.

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RHRadu Emil Hendea
Radu Emil Hendea
DRDoina Rǎducanu
Doina Rǎducanu
AAAdrián Claver Alba
Adrián Claver Alba
Jose GarciaJose Garcia
Jose Garcia
VCVasile Danut Cojocaru
Vasile Danut Cojocaru
RCRadu Septimiu Campian
Radu Septimiu Campian
The objective of this experimental work was to examine and characterise the route for obtaining demonstrative temporary biodegradable personalised implants from the Mg alloy Mg-10Zn-0.5Zr-0.8Ca (wt.%). This studied Mg alloy was obtained in its powder state using the mechanical alloying method, with shape and size characteristics suitable for ensuing 3D additive manufacturing using the SLM (selective laser melting) procedure. The SLM procedure was applied to various processing parameters. All obtained samples were characterised microstructurally (using XRD—X-ray diffraction, and SEM—scanning electron microscopy); mechanically, by applying a compression test; and, finally, from a corrosion resistance viewpoint. Using the optimal test processing parameters, a few demonstrative temporary implants of small dimensions were made via the SLM method. Our conclusion is that mechanical alloying combined with SLM processing has good potential to manage 3D additive manufacturing for personalised temporary biodegradable implants of magnesium alloys. The compression tests show results closer to those of human bones compared to other potential metallic alloys. The applied corrosion test shows result comparable with that of the commercial magnesium alloy ZK60.

9 November 2020 in Metals
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VCVasile Danut Cojocaru
Vasile Danut Cojocaru
ANANNA NOCIVIN
ANNA NOCIVIN
CTCorneliu Trisca-Rusu
Corneliu Trisca-Rusu
ADAlexandru Dan
Alexandru Dan
RIRaluca-Elena Irimescu
Raluca-Elena Irimescu
BGBogdan Mihai Galbinasu
Bogdan Mihai Galbinasu
The influence of complex thermo-mechanical processing (TMP) on the mechanical properties of a Ti-Nb-Zr-Fe-O bio-alloy was investigated in this study. The proposed TMP program involves a schema featuring a series of severe plastic deformation (SPD) and solution treatment (STs). The purpose of this study was to find the proper parameter combination for the applied TMP and thus enhance the mechanical strength and diminish the Young’s modulus. The proposed chemical composition of the studied β-type Ti-alloy was conceived from already-appreciated Ti-Nb-Ta-Zr alloys with high β-stability by replacing the expensive Ta with more accessible Fe and O. These chemical additions are expected to better enhance β-stability and thus avoid the generation of ω, α’, and α” during complex TMP, as well as allow for the processing of a single bcc β-phase with significant grain diminution, increased mechanical strength, and a low elasticity value/Young’s modulus. The proposed TMP program considers two research directions of TMP experiments. For comparisons using structural and mechanical perspectives, the two categories of the experimental samples were analyzed using SEM microscopy and a series of tensile tests. The comparison also included some already published results for similar alloys. The analysis revealed the advantages and disadvantages for all compared categories, with the conclusions highlighting that the studied alloys are suitable for expanding the database of possible β-Ti bio-alloys that could be used depending on the specific requirements of different biomedical implant applications.

8 March 2020 in Metals
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ECElisabeta Mirela Cojocaru
Elisabeta Mirela Cojocaru
DRDoina Rǎducanu
Doina Rǎducanu
ANANNA NOCIVIN
ANNA NOCIVIN
ICIon Cinca
Ion Cinca
AVAdrian Nicolae Vintila
Adrian Nicolae Vintila
VCVasile Danut Cojocaru
Vasile Danut Cojocaru
In this present study, the influence of isothermal aging temperature and duration on microstructural and mechanical properties of a hot-deformed UNS S32750 super duplex stainless steel (SDSS) alloy was investigated by SEM-EBSD (scanning electron microscopy-electron backscatter diffraction) and tensile testing techniques. An isothermal aging treatment, at temperatures between 400 and 600 °C and treatment duration between 3 and 120 h, was applied to a commercial UNS S32750 SDSS alloy. Microstructural characteristics of all thermomechanical (TM) processed states, such as distribution and morphology of constituent phases, grain’s modal orientation (MO), and obtained mechanical properties were analysed correlated with the TM processing conditions. The obtained experimental results show that the constituent phases, in all TM processed states, are represented by elongated γ-phase grains within the δ-phase matrix. The R-phase was observed in the case of aging treatment performed at 600 °C for 120 h. Within the δ-phase matrix, dynamically recrystallized grains were identified as a result of applying hot deformation and isothermal aging treatments. Also, it was observed that aging treatment parameters can significantly influence the mechanical behaviour exhibited by the UNS S32750 SDSS alloy, in terms of elongation to fracture and absorbed energy during impact testing.

15 November 2022 in Crystals
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DRDoina Rǎducanu
Doina Rǎducanu
VCVasile Danut Cojocaru
Vasile Danut Cojocaru
ANANNA NOCIVIN
ANNA NOCIVIN
RHRadu Emil Hendea
Radu Emil Hendea
SISteliana Ivanescu
Steliana Ivanescu
RCRadu Septimiu Campian
Radu Septimiu Campian
The aim of the present work was to apply a mechanical alloying method to obtain a Mg-10Zn-0.5Zr-0.8Ca powder-alloy with morphological and dimensional characteristics, proper for subsequent selective laser melting (SLM) processing. The mechanical alloying process was applied at different values of the milling time. Thus, the evolution of the main morphological and dimensional characteristics of the experimented powder-alloy could be studied. The conclusion of this study is that mechanical alloying possesses good potential to obtain powder-alloy with almost rounded morphology and fine dimensions, proper for further additive manufacturing procedures such as selective laser melting.

31 March 2022 in Materials
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RHRadu Emil Hendea
Radu Emil Hendea
DRDoina Rǎducanu
Doina Rǎducanu
ANANNA NOCIVIN
ANNA NOCIVIN
ISIvanescu Steliana
Ivanescu Steliana
DSDoina Ecaterina Stanciu
Doina Ecaterina Stanciu
BGBogdan Mihai Galbinasu
Bogdan Mihai Galbinasu
The aim of the present paper is to apply the laser powder bed fusion process to a new biodegradable Mg-Zn-Zr-Ca alloy powder prepared via a mechanical alloying method from powder pure components. This additive manufacturing method is expected to allow for the obtaining of high biomechanical and biochemical performance. Various processing parameters for laser powder bed fusion are tested, with a special focus on laser energy density—E [J/mm3]—which is calculated for all experiment variants, and which represents an important processing parameter, dependent upon all the rest. The goal of all the trials is to find the most efficient schema for the production of small biodegradable parts for the medical domain, meaning the selection of optimal processing parameters. An important observation is that the most robust and homogeneous samples without cracks are obtained for lower values of the E, around 100 J/mm3. Thus, the most performant samples are analyzed by scanning electron microscopy, X-ray diffraction and by compression mechanical test.