Yazar "Ustun, Erkan" seçeneğine göre listele
Listeleniyor 1 - 6 / 6
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Dendritic solidification and characterization of a succinonitrile-acetone alloy(IOP PUBLISHING LTD, 2006) Ustun, Erkan; Cadirli, Emin; Kaya, HasanA succinonitrile (SCN)-3.6 wt% acetone (ACE) alloy was unidirectionally solidified with a constant temperature gradient G = 5.7 K mm(-1) in the growth rate ranges V = 6.5 - 113 mu m s(-1) and a constant growth rate V = 6.5 mu m s(-1) in the temperature gradient ranges G = 3.5-5.7 K mm(-1). The primary dendrite arm spacings, secondary dendrite arm spacings, dendrite tip radius and mushy zone depth were measured as a function of growth rate and temperature gradient. Theoretical models for the dendrite arm spacing and tip radius have been compared with the experimental observations, and a comparison of our results with the current theoretical models and previous experimental results has also been made. The stability constant (s) for this alloy system was measured and this result was compared with various similar organic transparent alloys.Öğe Determination of the thermal properties of ternary Al-La-Ni cast alloy(Natl Inst Science Communication-Niscair, 2022) Cadirli, Emin; Ustun, ErkanIn current work, thermal conductivity, enthalpy of fusion, specific heat, and thermal diffusivity of the Al-8.8La-1.2Ni cast alloy has been investigated. Chemical element analysis of the studied alloy was determined with X-Ray Fluorescence Spectrometer (XRF) and SEM microscopy with Energy Dispersive X-Ray Spectroscopy (EDS). Thermal conductivity of as -cast Al-8.8La-1.2Ni alloy was measured using comparison cut bar method in the temperature range of 308???773 K. Thermal conductivity values decreased gradually in the studied alloy with the increase of temperature. The thermal temperature coefficient was calculated from the thermal conductivity-temperature graph. The heat flow-temperature curve was obtained by performing Differential Scanning Calorimetry (DSC) analysis. Enthalpy of fusion and specific heat values were also determined. Thermal diffusivity values were calculated as a function of temperature using the relevant equation. It was determined that the thermal diffusivity values increased with increasing temperature.Öğe EFFECT OF GROWTH RATE ON COARSENING OF SECONDARY DENDRITE ARM SPACINGS IN DIRECTIONALLY SOLIDIFIED OF Al-8.8La-1.2Ni TERNARY ALLOY(Polska Akad Nauk, Polish Acad Sciences, Inst Metall & Mater Sci Pas, 2022) Ustun, Erkan; Cadirli, EminOne of the most important factors directly affecting microstructure and mechanical properties in directional solidification process is secondary dendrite arm spacing (SDAS). It is very important to measure the SDAS and examine the factors that may affect them. To investigate the effort of growth rate on the SDAS, the alloy specimens were directional solidified upward with different growth rates ( V= 8.3-83.0 mu m/s) at a constant temperature gradient (G = 4 K/mm) in a Bridgman-type growth apparatus. After the specimens are directionally solidified, they were exposed to metallographic processes in order to observe the dendritic solidification structure on the longitudinal section of the specimens. Coarsen secondary dendrite ann spacings (lambda(2C)) were measured excluding the first arms near the tip of the dendrite. Local solidification times (t(f)) were calculated by ratio of spacings to growth rates. It was detennined that the t(f) values decreased with increasing V values. The relationships between t(f) and lambda(2C) were defined by means of the binary regression analysis. Exponent values of t(f) were obtained as 0.37, 0.43, 0.46 and 0.47 according to increasing V values, respectively. These exponent values are close to the exponent value (0.33) predicted by the Rappaz-Boettinger theoretical model and good agreement with the exponent values (0.33-0.50) obtained by other experimental studies.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 Investigation of the microstructure and physical properties of directionally solidified ternary Al-8.8La-1.2Ni alloy(Elsevier Science Sa, 2021) Ustun, Erkan; Cadirli, EminThis paper systematically studies the microstructure evolution, microhardness and tensile property of Al-8.8La-1.2Ni ternary alloy with directionally solidified under a wide range of solidification rates by Bridgman-type growth apparatus. The directionally solidified microstructure of studied alloy consists aligned dendrites, and eutectics in the region between them. Primary dendrite arm spacing (lambda(1)), secondary dendrite arm spacing (lambda(2)) and microhardness (HV) were measured from both transverse and longitudinal sections of many samples. Also, ultimate tensile strength (sigma(uts)), tensile yield strength (sigma(tys)), ultimate compressive strength (sigma(ucs)) and compressive yield strength (sigma(cys)) of the solidified many samples at room temperature the dependence of solidification rate (V) were carried out. The present results show that the solidification rate can change both microstructure and mechanical properties effectively. According to these results, it has been found that, for increasing values of V, the values of lambda(1) and lambda(2) decrease, the values of HV, sigma(uts), sigma(tys), and sigma(cys), increase. Relationships between microstructural parameters (lambda(1, )lambda(2)) and mechanical properties (HV, sigma(uts), sigma(tys), and sigma(cys)) expressed as function of solidification rate using a linear regression analysis method. (C) 2020 Elsevier B.V. All rights reserved.
