Yazar "Gunduz, Mehmet" seçeneğine göre listele
Listeleniyor 1 - 12 / 12
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Dependency of structure, mechanical and electrical properties on rotating magnetic field in the Bi-Sn-Ag ternary eutectic alloy(CARL HANSER VERLAG, 2016) Kaya, Hasan; Cadirli, Emin; Gunduz, Mehmet; Raebiger, Dirk; Eckert, SvenIn the present study, cylindrical samples of the Bi-Sn-Ag ternary eutectic alloy were exposed to a rotating magnetic field (RMF) during upward solidification. The dependence of the eutectic spacing (lambda), microhardness (HV), tensile stress (sigma) and electrical resistivity (rho) of the Bi-Sn-Ag eutectic alloy on the RMF-driven flow was investigated in this study. With the increase in the RMF, the eutectic grains are fragmented and gradually refined until a transition from coarser plate-like structure to a fine fibrous eutectic structure for the alloy. It was found that with the increasing of RMF, lambda decreases but HV, sigma and rho increase. The enthalpy of fusion (Delta H) and specific heat (C-p) for the same alloy was determined by means of differential scanning calorimetry from the heating trace during the transformation from the eutectic liquid to eutectic solid. The results obtained in the present work were compared with published data available in the literature.Öğe Effect of Growth Rate on the Microstructure and Microhardness in a Directionally Solidified Al-Zn-Mg Alloy(SPRINGER, 2016) Acer, Emine; Cadirli, Emin; Erol, Harun; Gunduz, MehmetThe Al-5.5Zn-2.5Mg (wt pct) ternary alloy was prepared using a vacuum melting furnace and a casting furnace. Five samples were directionally solidified upwards at a constant temperature gradient (G = 5.5 K/mm) under different growth rates (V = 8.3-165 mu m/s) in a Bridgman-type directional solidification furnace. The primary dendrite arm spacing, lambda (1), secondary dendrite arm spacing, lambda (2), and microhardness, HV, of the samples were measured. The effects of V on lambda (1), lambda (2) and HV properties of the Al-Zn-Mg alloy were studied by microstructure analysis and mechanical characterization. Microstructure characterization of the alloys was carried out using optical microscopy, scanning electron microscopy, wavelength-dispersive X-ray fluorescence spectrometry, and energy dispersive X-ray spectroscopy. From the experimental results, it is found that the lambda (1), lambda (2) values decrease, but HV values increase with the increase in V, and HV values decrease with the increase in lambda (1) and lambda (2). Dependencies of dendritic spacing and microhardness on the growth rate were determined using linear regression analysis. The growth rate, microstructure, and Hall-Petch-type relationships obtained in this work have been compared with the results of previous studies.Öğe Effect of Growth Velocity and Zn Content on Microhardness in Directionally Solidified Al-Zn Alloys(Univ Fed Sao Carlos, Dept Engenharia Materials, 2018) Acer, Emine; Cadirli, Emin; Erol, Harun; Kaya, Hasan; Sahin, Mevlut; Gunduz, MehmetIn this study, Al-xZn (x=1, 3, 5, 7, 10 and 20 wt. %) alloys were prepared using metals of 99.99% high purity in the vacuum atmosphere. These alloys were directionally solidified upward with a constant temperature gradient, G (10.3 K/mm) and different growth velocities (V) between 8.25 and 165 mu m/s in the directional solidification apparatus. The experimental results have revealed that with the increase of the growth velocity of the melts from 8.25 mu m/s to 165 mu m/s, the microstructures undergo a transition from cellular/cellular dendritic morphology to coarse dendritic form for each composition (Zn content, C-o). The measurements of microhardness (HV) of the specimens were performed by using a microhardness test device. The dependence of HV on V and C(o )was analyzed, and it has been found that with increasing the V and C-o the HV increases. Relationships between HV-V and HV-C-o were obtained by linear regression analysis, and the experimental results were compared with the results of previous similar works.Öğe Effect of growth velocity on microstructure and mechanical properties of directionally solidified 7075 alloy(Taylor & Francis Ltd, 2020) Cadirli, Emin; Nergiz, Emel; Kaya, Hasan; Buyuk, Ugur; Sahin, Mevlut; Gunduz, Mehmet7075 alloys were prepared using metals of 99.99% high purity in the vacuum atmosphere. These alloys were directionally solidified upwards under various growth velocities (8.3-166.0 mu m/s) using a Bridgman-type directional solidification furnace. Dendritic spacings (lambda(1), lambda(2)) and microhardness (HV) were measured from both longitudinal and transverse sections of the samples. Ultimate tensile strength (sigma(U)) and yield strength (sigma(y)) of the solidified samples at room temperature were examined. The HV increased from 75.2 to 112.8 MPa, the sigma(U) increased from 155.8 to 210.1 MPa, and the sigma(y) increased from 198.4 to 319.8 MPa with increasing growth velocity from 8.3 to 166.0 mu m/s. Exponent values of the V for the lambda(1), lambda(2), HV, sigma(U) and sigma(y) were calculated as 0.27, 0.41, 0.05, 0.11 and 0.15, respectively. The results show that the hot tearing in the 7075 alloy is caused by the fracture of dendrites structures.Öğe Effect of Heat Treatment on the Microstructures and Mechanical Properties of Al-4Cu-1.5Mg Alloy(Springer Int Publ Ag, 2022) Cadirli, Emin; Kaya, Hasan; Buyuk, Ugur; Ustun, Erkan; Gunduz, MehmetIn this work, the influence of different heat treatments (HT) processes on the microstructure and mechanical properties of cast Al-4Mg-1.5 Mg alloy was investigated. To investigate the effect of HT, firstly Al-4Cu-1.5Mg samples were homogenized (solution treatment) at 500 degrees C/2h, water quenched at room temperature (RT) and then immediately exposed to an artificial aging process at 200 degrees C for various aging times of 1, 4, 8, 12, 16, 20 and 24 hours. Quantitative examinations after HT processes (solution treatment and aging) have shown that intermetallic phases (Al2Cu and Al2CuMg) were dissolved in the alpha-Al matrix phase and distributed along the grain boundary. Some mechanical properties (HV sigma, sigma(TYS), sigma(UTS), sigma(CYS), E and delta) of a sufficient number of alloy samples exposed to different heat treatments were examined in detail. The data obtained show that the conditions of solution treatment and aging in some conditions show superior mechanical properties than the sample in the form as-cast. The highest microhardness value (126 HV) was obtained for the alpha-Al matrix phase, which was subjected to solution treatment (only homogenization). After aging for 1h at 200 degrees C, the peak value of microhardness was achieved as 289.5 HV for intermetallic phases. The highest tensile strength (sigma(UTS)) was obtained as 328 MPa for the sample which aged for 8h at 200 degrees C after solution treatment for 2h at 500 degrees C.Öğe EFFECT OF HEAT TREATMENT ON THE MICROSTRUCTURES AND MECHANICAL PROPERTIES OF AL-4CU-1.5MG ALLOY (vol 16, pg 1020, 2021)(Springer Int Publ Ag, 2024) Cadirli, Emin; Kaya, Hasan; Buyuk, Ugur; Ustun, Erkan; Gunduz, Mehmet[Abstract Not Available]Öğe Effect of heat treatment on the microstructures and mechanical properties of Al-5.5Zn-2.5Mg alloy(ELSEVIER SCIENCE SA, 2016) Acer, Emine; Cadirli, Emin; Erol, Harun; Kirindi, Talip; Gunduz, MehmetThe Al-5.5 Zn-2.5 Mg (wt%) ternary alloy was prepared using a vacuum melting furnace and a casting furnace. Microstructural and mechanical properties of the alloy were investigated as-cast and under heat-treated conditions. To investigate the effect of heat treatment, numerous designed Al-5.5 Zn-2.5 Mg samples were homogenized under different conditions and then aged under different regimes. The effects of heat treatment on the microstructures were examined by OM, SEM, and TEM, and mechanical properties of the Al-Zn-Mg alloy were studied. A good combination of high microhardness and reasonable tensile strength were obtained by successive and suitable heat treatments. After aging for 24 h at 150 degrees C, the peak microhardnes and tensile strength values were achieved as 157 MPa and 188.8 MPa, respectively. The microscopic fracture surfaces of the aged samples under different homogenization and aging conditions were observed using scanning electron microscopy. Fractographic analysis of the tensile fracture surfaces shows that the type of fracture changed significantly from ductile to more ductile depending on the aging regime. (C) 2016 Elsevier B.V. All rights reserved.Öğe Effect of heat treatments on the microhardness and tensile strength of Al-0.25 wt.% Zr alloy(ELSEVIER SCIENCE SA, 2015) Cadirli, Emin; Tecer, Hicran; Sahin, Mevlut; Yilmaz, Elif; Kirindi, Talip; Gunduz, MehmetIn the present work, the effect of heat treatments on the microhardness and tensile properties of the Al-0.25 Zr (wt.%) alloy have been investigated. The Al-0.25 Zr (wt.%) alloy was melted in a vacuum furnace, and the molten alloy was poured into crucibles held in a hot filing furnace. Then, the samples were directionally solidified from bottom to top and aged isothermally and isochronally in a muffle furnace. Aging was performed in two ways: using a wide range of temperatures (350-600 degrees C) with a constant aging time (100 h) and a wide range of aging times (3-240 h) with a constant temperature (400 degrees C). The dependence of the microhardness (HV) and ultimate tensile strength (sigma(UTS)) on the aging temperatures and aging times was determined. According to the experimental results, the HV and sigma(UTS) values of the aged samples increase at a certain aging temperature and aging time values, reaching peak values at specific temperatures and aging times. The microhardness and ultimate tensile strength decreased with further increase of aging temperatures and aging times. The microscopic fracture surfaces of the aged samples under different aging conditions were observed using scanning electron microscopy. Fractographic analysis of the tensile fracture surfaces shows that the type of fracture changed significantly from ductile to brittle depending on the aging times. Transmission electron microscopy was also used to characterize the precipitation processes in an Al-0.25 Zr (wt.%) alloy aged at 400 degrees C for 120 h. (C) 2015 Elsevier B. V. All rights reserved.Öğe Effect of rotating magnetic field on the microstructures and physical properties of Al-Cu-Co ternary eutectic alloy(ELSEVIER SCIENCE SA, 2015) Cadirli, Emin; Kaya, Hasan; Raebiger, Dirk; Eckert, Sven; Gunduz, MehmetThe solidification microstructures and physical properties of Al-Cu-Co ternary eutectic alloy were studied in a rotating magnetic field (RMF). The RMF-driven flow was the key factor causing grain refinement and uniformity of solidification microstructures. The temperature distributions during solidification were recorded under the conditions with and without RMF. The dependence of the eutectic spacing (lambda), the microhardness (HV), tensile strength (sigma(t)) and compressive strength (sigma(c)) on the RMF were investigated. Electrical resistivity (rho) measurements of the studied alloy were also performed by using the four-point probe method and the dependence of the resistivity on temperature and RMF were determined. Besides, the enthalpy (Delta H) and the specific heat (C-p) values were determined by the differential scanning calorimeter (DSC) analysis. Important changes were found in the microstructure, microhardness, tensile strength, compressive strength and electrical resistivity of the studied alloy with increasing RMF. (C) 2015 Elsevier B.V. All rights reserved.Öğe Measurement and Prediction of the Thermal and Electrical Conductivity of Al-Zr Overhead Line Conductors at Elevated Temperatures(Univ Fed Sao Carlos, Dept Engenharia Materials, 2019) Kahveci, Osman; Cadirli, Emin; Ari, Mehmet; Tecer, Hicran; Gunduz, MehmetIn the present work, the thermal conductivity and electrical resistivity of the Al-0.25 Zr (wt.%) alloy have been investigated from 300 K to 600 K. The variations of thermal conductivity (K-total) with temperature were measured by using a radial heat flow furnace. The electrical resistivity (rho) measurements of the alloy depending on the temperature were performed using the standard four-point probe method. The electrical conductivity (sigma) was obtained by using the measured electrical resistivity. The thermal conductivity and the electrical resistivity coefficients were determined from the graphs of thermal and electrical resistivity versus temperature for the alloy. The electronic thermal conductivity (K-e) values were obtained from the Wiedemann-Franz and Smith-Palmer equations, and the values of K-L were obtained by subtracting K-e fromthe measured values (K-total). K-total is dominated by Ke, and K-e varies between 208-198 W/mK. The K-L decreases from 7.99 to 1.77 W/m K, and s varies between 1.41x10(7)-2.80x10(7) Omega(-1)m(-1) in the range of temperature 373-600 K. The enthalpy of fusion (Delta H) and the specific heat capacity (C-p) during the transformation were determined. Thermal diffusivity (alpha) changes were calculated as a function of temperature from these obtained thermal data.Öğe Microstructural Evolution and Mechanical Properties in Directionally Solidified Sn-10.2 Sb Peritectic Alloy at a Constant Temperature Gradient(UNIV FED SAO CARLOS, DEPT ENGENHARIA MATERIALS, 2016) Yilmaz, Elif; Cadirli, Emin; Acer, Emine; Gunduz, MehmetThe Sn-10.2 Sb (mass fraction) peritectic alloy was prepared using a vacuum melting furnace and a hot filling furnace. The samples were directionally solidified upwards at steady state conditions with a constant temperature gradient (G = 4.5 +/- 0.2 K. mm(-1)) under different growth velocities (V = 13.3-266.7 mu m. s(-1)) in a Bridgman-type directional solidification apparatus. The effects of the growth velocity (V) on the dendritic spacings were investigated. Primary dendrite arm spacing (PDAS) of a phase in directionally solidified Sn-10.2 Sb peritectic alloy was measured on the longitudinal and transverse sections of 4 mm diameter cylindrical samples. Secondary dendrite arm spacing (SDAS) was measured on the longitudinal section. The experimental results show that the measured PDAS (lambda(IL),lambda(IT)) and SDAS (lambda(2)) decrease with increasing growth velocity. The dependence of PDAS, SDAS, microhardness (HV) and compressive strength (sigma(c)) on the growth velocity were determined by using a linear regression analysis. The experimental results were compared with the previous experimental results and the results of the experimental models.Öğe The Effect of Growth Rate on the Microstructure and Mechanical Properties of 7020 Alloys(Springer, 2022) Kaya, Hasan; Buyuk, Ugur; Cadirli, Emin; Sahin, Mevlut; Gunduz, MehmetThe 7020 aluminum alloy is one of the hardenable Al-Zn-Mg based alloys, which are a family of high strength aluminum alloys. These 7020 alloys are commonly used in the aircraft and automotive industries. The microstructural changes have a significant impact on the mechanical properties of binary and multi-component alloys. For this reason, 7020 aluminum alloys were prepared with different growth rates on account of the changes in the microstructures; thus, directionally solidification processes were actualized with a Bridgman furnace at five various growth rates (V = 8.3-166.0 mu m/s) and at constant temperature gradient (G = 8.3 K/mm). Microhardness (HV), ultimate tensile strength (sigma(U)) and yield strength (sigma(y)) of the solidified alloys were determined. The HV increased from 758.8 to 917.1 N/mm(2), the sigma(U) from 125.4 to 208.1 N/mm(2) and the sigma(y) from 133.7 to 230.8 N/mm(2) with an increase in growth rate from 8.3 to 166.0 mu m/s.
