Kalay, İlkay
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Kalay, I.
Kalay, I
Kalay, İlkay
Kalay, Ilkay
Kalay, İlkay
Kalay, İlkay
Kalay, İlkay
Kalay, I
Kalay, İlkay
Kalay, Ilkay
Kalay, İlkay
Kalay, İlkay
Kalay, İlkay
Job Title
Dr. Öğr. Üyesi
Email Address
ikalay@cankaya.edu.tr
Main Affiliation
06.08. Mekatronik Mühendisliği
06. Mühendislik Fakültesi
01. Çankaya Üniversitesi
06.08. Mekatronik Mühendisliği
Mekatronik Mühendisliği
06. Mühendislik Fakültesi
01. Çankaya Üniversitesi
06. Mühendislik Fakültesi
01. Çankaya Üniversitesi
06.08. Mekatronik Mühendisliği
Mekatronik Mühendisliği
06. Mühendislik Fakültesi
01. Çankaya Üniversitesi
Status
Current Staff
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Scholarly Output
15
Articles
14
Views / Downloads
672/11
Supervised MSc Theses
0
Supervised PhD Theses
0
WoS Citation Count
153
Scopus Citation Count
348
Patents
0
Projects
0
WoS Citations per Publication
10.20
Scopus Citations per Publication
23.20
Open Access Source
3
Supervised Theses
0
| Journal | Count |
|---|---|
| Metallurgical and Materials Transactions A | 5 |
| Materials Science and Engineering: A | 2 |
| Intermetallics | 1 |
| Journal of Alloys and Compounds | 1 |
| Metallurgical And Materials Transactions A-Physical Metallurgy And Materials Science | 1 |
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15 results
Scholarly Output Search Results
Now showing 1 - 10 of 15
Article Kinetics and mechanisms of isothermal devitrification inamorphous cu50zr50(Springer, 2015) Cullinan, Tim; Kalay, İlkay; Kalay, Y. Eren; Kramer, Matt; Napolitano, RalphThe crystallization kinetics and microstructural dynamics associated with devitrifying a melt-spun Cu50Zr50 metallic glass were investigated using isothermal treatments, in situ high-energy synchrotron X-ray diffraction, conventional and high-resolution transmission electron microscopy, and differential scanning calorimetry. The analysis of isothermal transformations allows us to more clearly unravel the complex interplay between nucleation and growth of competing stable and metastable phases. The isothermal devitrification response was found to involve the Cu10Zr7, CuZr2, and CuZr phases, consistent with previously reported constant heating rate experiments, but here we have resolved the phase evolution and structural characteristics of the transformation, including the very early stages of crystallization. At 671 K (398 A degrees C), the isothermal transformation starts with the formation of the Cu10Zr7 phase, which grows in a generally equiaxed morphology. At a size of approximately 100 nm, the growth of the Cu10Zr7 particles is interrupted by the precipitation of a thin layer of the CuZr2 phase, upon which the metastable CuZr (B2) grows epitaxially. Crystallization kinetics are quantified here though in situ measurements (HEXRD, DSC) and ex situ microstructural analysis (TEM, HRTEM). Finally, the influences of chemical partitioning, diffusion, and crystallographic orientation on this sequence are examined.Correction The Anomalous Nucleation in Al-Tb Metallic Glasses (Vol 52a, Pg 700, 2021)(Springer, 2021) Ulucan, T. H.; Kalay, I.; Kalay, Y. E.Article Citation - WoS: 25Citation - Scopus: 27Crystallization Kinetics and Phase Transformation Mechanisms in Cu56zr44 Glassy Alloy(Springer, 2015) Kramer, Matthew J.; Napolitano, Ralph E.; Kalay, IlkayThe kinetics and phase selection mechanisms involved in the crystallization of an amorphous Cu-Zr alloy of eutectic composition (Cu56Zr44) were investigated using in situ high-energy X-ray diffraction (HEXRD), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) under isothermal and constant heating rate conditions. In situ HEXRD results for 10 K/min (10 A degrees C/min) heating indicate that the amorphous alloy devitrifies into CuZr2 and mainly Cu10Zr7 at the crystallization temperature of 725 K (452 A degrees C). The sequence continues with the precipitation of CuZr (B2) at 1004 K (731 A degrees C), where these three phases coexist until the decomposition of CuZr2 is observed at 1030 K (757 A degrees C). The two equilibrium phases Cu10Zr7 and CuZr (B2) remain present on further heating until melting at the eutectic temperature for the Cu56Zr44 alloy. TEM investigation of the isothermal [705 K (432 A degrees C)] crystallization sequence reveals primary nucleation and growth of the Cu10Zr7 phase, where growth of the Cu10Zr7 crystals is initially planar with a transition to a cellular morphology, associated with partitioning of Zr at the growth front. Related cellular structures and composition profiles are quantified. (C) The Minerals, Metals & Materials Society and ASM International 2015Article Citation - WoS: 3Citation - Scopus: 3Nanomechanical Properties of Al-Tb Marginal Metallic Glass(Elsevier Science Sa, 2023) Okuyucu, Can; Ulucan, Tolga Han; Abboud, Mohammad; Motallebzadeh, Amir; Ozerinc, Sezer; Kalay, Ilkay; Kalay, Yunus ErenAl-Rare Earth (RE) metallic glasses provide an effective model system to study the effect of nanocrystallites in an amorphous matrix on nanomechanical behavior. In this work, we achieved a series of Al-Tb metallic glasscrystalline composites with systematically varying crystalline content through annealing. The nanomechanical properties were characterized using micropillar compression tests and nanoindentation for as-quenched amorphous and annealed amorphous/nanocrystalline composite specimens. The promising hardness increases after annealing from 3.0 GPa to 4.6 GPa and elastic modulus increment from 68 GPa to 92 GPa were discussed in detail, considering the structural features of Al-RE marginal metallic glass formers. The increase in elastic modulus is associated with the nucleated fcc-Al nanocrystals that divide the amorphous matrix, leading to the branching of the shear bands. The correlation between the fcc-Al nanocrystals and the behavior of shear bands was discussed in detail.Article Citation - WoS: 7Citation - Scopus: 7Investigation of Phase Selection Hierarchy in Mn-Al Alloys(Elsevier Sci Ltd, 2019) Acar, Ozgun; Turan, Servet; Kalay, Ilkay; Savaci, Umut; Kalay, Yunus Eren; Genc, Ayse MervePrimarily attributed to the formation of the ferromagnetic tau-phase, near equiatomic composition of Mn-Al have recently received much attention in permanent magnet industry. Several mechanisms have been proposed in literature for the tau-phase formation but controversy still arises regarding the dominating mode. In the current work, MnAl-based alloys having different compositions in a range between Mn50.5Al49.5 and Mn57Al43 have been studied by means of in-situ high energy X-ray diffraction, differential scanning calorimetry (DSC) and magnetic measurements. Synchrotron and DSC experiments showed the dependence of the tau-MnAl on the intermediate disordered epsilon'-phase. Alloys having 53.4 at% or less Mn (S1, S2) followed a transformation route of epsilon+epsilon'-> tau ->beta+gamma(2) upon annealing. Alloys having more than 53.4 at% of Mn had only epsilon-phase. High energy X-ray diffraction patterns showed that epsilon-phase directly transformed into stable phases in the absence of epsilon'-phase. It is observed that epsilon' not only promoted the ferromagnetic tau-phase but also stabilized it by delaying the nucleation of stable phases.Article Citation - WoS: 23Citation - Scopus: 24Kinetics and Mechanisms of Isothermal Devitrification in Amorphous Cu50zr50(Springer, 2015) Kalay, Ilkay; Kalay, Y. Eren; Kramer, Matt; Napolitano, Ralph; Cullinan, TimThe crystallization kinetics and microstructural dynamics associated with devitrifying a melt-spun Cu50Zr50 metallic glass were investigated using isothermal treatments, in situ high-energy synchrotron X-ray diffraction, conventional and high-resolution transmission electron microscopy, and differential scanning calorimetry. The analysis of isothermal transformations allows us to more clearly unravel the complex interplay between nucleation and growth of competing stable and metastable phases. The isothermal devitrification response was found to involve the Cu10Zr7, CuZr2, and CuZr phases, consistent with previously reported constant heating rate experiments, but here we have resolved the phase evolution and structural characteristics of the transformation, including the very early stages of crystallization. At 671 K (398 A degrees C), the isothermal transformation starts with the formation of the Cu10Zr7 phase, which grows in a generally equiaxed morphology. At a size of approximately 100 nm, the growth of the Cu10Zr7 particles is interrupted by the precipitation of a thin layer of the CuZr2 phase, upon which the metastable CuZr (B2) grows epitaxially. Crystallization kinetics are quantified here though in situ measurements (HEXRD, DSC) and ex situ microstructural analysis (TEM, HRTEM). Finally, the influences of chemical partitioning, diffusion, and crystallographic orientation on this sequence are examined.Article Citation - WoS: 11Citation - Scopus: 14Nanocrystallization in Cu-Zr Bulk Metallic Glasses(Springer, 2018) Yasar, Bengisu; Kalay, Ilkay; Sikan, FatihThe effect of rare-earth element (Sm) microalloying on the thermal stability and crystallization kinetics of melt-spun ribbons and suction-cast rods of Zr48Cu38.4Al9.6Sm4 alloy were investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), and atom probe tomography (APT). The XRD results of constant heating rate annealing indicated that amorphous Zr48Cu38.4Al9.6Sm4 melt-spun ribbons devitrifies into Cu2Sm at 673 K (400 A degrees C). The sequence continues with the precipitation of Cu10Zr7 and then these two phases coexist. XRD and TEM studies on 1 mm diameter as suction-cast rods indicated the precipitation of 30-nm-mean size Cu2Sm crystals during solidification. TEM investigation of the isothermal crystallization sequence of melt-spun ribbons and 1-mm-diameter suction-cast rods revealed the precipitation of Cu2Sm nanocrystals at the onset of crystallization and the restriction of the growth of these nanocrystals up to 10 nm diameter with further annealing. APT analysis of 1-mm-diameter suction-cast rods showed that the limited growth of Cu2Sm nanocrystals is due to sluggish diffusion of Sm and Al-Zr pile up at the interface.Article Citation - WoS: 8Citation - Scopus: 9Effect of Sm on Thermal and Mechanical Properties of Cu-Zr Bulk Metallic Glasses(Elsevier Science Sa, 2019) Sikan, F.; Atabay, S. E.; Motallebzadeh, A.; Ozerinc, S.; Kalay, I.; Kalay, Y. E.The effect of rare-earth (Sm) microalloying on the thermal stability and phase selection along with the effect of nanocrystallization on the mechanical properties of amorphous melt-spun ribbons of Zr50Cu40Al10, Zr49Cu39.2Al9.8Sm2 and Zr48Cu38.4Al9.6Sm4 alloys were investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), Vickers and nanoindentation hardness tests and micropillar compression analysis. XRD and TEM analyses showed that all samples were fully amorphous in as-spun state; however, crystallization sequences for the Sm-free and the Sm micro-alloyed samples were different during devitrification. Combined study of XRD, DSC and TEM on melt-spun ribbons show that Zr48Cu38.4Al9.6Sm4 have nanocrystallization of Cu2Sm phase with an average diameter of 10 nm, which was absent in Zr50Cu40Al10, prior to crystallization of Cu10Zr7 phase. The nanoindentation and micropillar compression tests revealed Cu2Sm nanocrystals embedded in Zr48Cu38.4Al9.6Sm4 alloy improves strength and hardness. On the other hand, presence of these nanocrystals deteriorate shear band stability and thus result in a catastrophic brittle fracture through a single shear band burst.Article Citation - WoS: 5Citation - Scopus: 4The Anomalous Nucleation in Al-Tb Metallic Glasses(Springer, 2021) Kalay, I.; Kalay, Y. E.; Ulucan, T. H.The effects of amorphous structure on the devitrification of Al90Tb10 marginal glass former system were investigated in detail by a combined study of high-energy X-ray diffraction (HEXRD), X-ray absorption fine structure (EXAFS), reverse Monte Carlo simulations (RMC), transmission electron microscopy (TEM) and thermal analyses. The atomic structures of melt-spun ribbons and magnetron sputtered amorphous samples with the same composition were simulated using RMC constrained by XRD, EXAFS, and ab-initio results. The fcc-Al nanocrystals nucleated and grown in thin-film specimens have a limited size with almost perfect spherical morphology. The population of these nanocrystals is three orders of magnitude higher as compared to ribbon specimens. The differences in the devitrified ribbon and thin-film metallic glasses were traced back to structural differences in the amorphous state. The amorphous melt-spun ribbons and magnetron sputtered thin- films were found to have different degrees of short-range order and clustering.Article Citation - Scopus: 185Nanoscale Structure and Structural Relaxation in Zr 50cu 45al 5 Bulk Metallic Glass(2012) Melgarejo, Z.H.; Kalay, Y.E.; Kalay, I.; Kramer, M.J.; Stone, D.S.; Voyles, P.M.; Hwang, J.Hybrid reverse Monte Carlo simulations of the structure of Zr 50Cu 45Al 5 bulk metallic glass incorporating medium-range structure from fluctuation electron microscopy data and short-range structure from an embedded atom potential produce structures with significant fractions of icosahedral- and crystal-like atomic clusters. Similar clusters group together into nanometer-scale regions, and relaxation transforms crystal-like clusters into icosahedral clusters. A model refined against only the potential does not agree with the fluctuation microscopy data and contains few crystal-like clusters. © 2012 American Physical Society.
