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Öğe The Effect of ?2-Phase (Ti3Al) on the Wear Behavior of Titanium Alloys Added Small Amounts of Fe(Polish Acad Sciences Inst Physics, 2017) Simsek, I.; Ozyurek, D.In the present study, the effect of alpha(2)-phase (Ti3Al) on the wear behavior of the titanium alloys is investigated by adding different amounts of (0.3-0.5%) Fe to the Ti8Al2.5Sn and Ti5Al2.5Sn alloys, which are produced by the mechanical alloying. The pre-formed green compacts were sintered at 1200 degrees C for one hour. The sintered samples were characterized by scanning electron microscope, X-ray diffraction, and the hardness and density measurements. The wear tests were performed under 30 N load, at four different sliding distances (400-1600 m) and with a constant speed of 1 ms(-1). As a result of the study, it was understood that the alpha(2)-phase (Ti3Al) in the structure occurred at the grain boundary during the sintering process. With an increase in Fe addition to the Ti8Al2.5Sn and Ti5Al2.5Sn alloys, the density and hardness of the alloy increased as well. As a result of the wear tests, it was determined that the least weight loss occurred in Ti5Al2.5Sn alloy with a 0.5% Fe addition.Öğe The Effect of Ageing Temperature in T6 Heat Treatment on Mechanical Properties of AA7075(Polish Acad Sciences Inst Physics, 2019) Simsek, I.; Simsek, D.; Tuncay, T.; Ozyurek, D.In this study, the effect of ageing temperatures in T6 heat treatment on the microstructural changing and mechanical properties of AA7075 were investigated. The samples were quenched after solution treatment at 485 degrees C for 2 h. The natural ageing was applied for 1 h, and then artificial ageing was carried out at five different temperatures (100-140 degrees C) for 24 h. Hardness measurements, microstructure, X-ray diffraction examinations, and tensile tests of aged samples were carried out. As a result of the study, the hardness values and ultimate tensile stress values were increased by increasing ageing temperatures up to 120 degrees C. Then it was decreased by increasing ageing temperature. Ultimate tensile stress values were compatible with hardness values and maximum ultimate tensile stress values were obtained in aged samples at 120 degrees C.Öğe The effect of the aging time on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment(G.V. Kurdyumov Institute for Metal Physics of N.A.S. of Ukraine, 2019) Simsek, I.; Simsek, D.; Ozyurek, D.; Tekeli, S.In this study, the effect of the aging time on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment is investigated. The AA7075 alloys are quenched after solid solution treatment at 485°C for 2 hours and artificially aged at 120°C using five different aging times. Hardness measurements, microstructure examinations (SEM + EDS, XRD), and tensile tests are performed for the aged alloys. Fractured surfaces are also examined using SEM images after the tensile testing. The results of the studies conducted show that the hardness value of the alloys can be increased by increasing aging time, and the maximum hardness value of 192 HV is obtained for the alloy aged for 25 hours. Tensile tests also show that the tensile strength of the alloy can be increased by increasing aging time, and the maximum tensile strength value of 580 MPa is obtained for the alloy aged for 25 hours. Fractured surface examinations revealed that the ductile fracture mechanism is mostly dominant, while the planar fracture mechanism is observed as well. © 2019 G. V. Kurdyumov Institute for Metal Physics, National Academy of Sciences of Ukraine.Öğe The Effects of Aging Temperature on the Corrosion and Electrical Conductivity in the AA7075 Alloy Produced by Powder Metallurgy Method(Polish Acad Sciences Inst Physics, 2019) Simsek, I.; Nalcacioglu, C.; Ozyurek, D.In this study, the effect of aging temperature of corrosion and electrical conductivity of AA7075 produced by powder metallurgy method was investigated. Produced AA7075 Al alloy samples, obtained by powder metallurgy method, were quenched after solution treatment at 485 degrees C for 2 h. Then they were aged at three different temperatures (110 degrees C, 120 degrees C, and 130 degrees C) for 24 h. Aged samples hardness and density measurements were carried out and they were characterized by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Corrosion tests were carried out using potentiodynamic polarization technique, a cyclic polarization measurement at a scan interval of +/- 750 mV and scan rate of 1 mV/s in 0.1 M H2SO4 solution. Electrical conductivity values were calculated (IACS%) according to ASTM B193-02 standards. As a result of the study, the highest hardness values were measured with aged samples at 120 degrees C. In addition, the lowest electrical conductivity and the lowest corrosion resistances values were obtained with aged samples at 120 degrees C.Öğe An investigation of the effect of high-energy milling time of Ti6Al4V biomaterial on the wear performance in the simulated body fluid environment(Taylor & Francis Ltd, 2017) Simsek, I.; Ozyurek, D.In this study, the effect of milling time on wear behaviour of the Ti6Al4V alloy produced with the high-energy milling method was investigated. The Ti6Al4V alloy was milled at five different milling times in a mechanical alloying device. The milled powders were cold-pressed under 620 MPa pressure, sintered at 1300 degrees C for 2 h and cooled to room temperature in the furnace. The sintered alloys were characterised with SEM, XRD and hardness and density measurements. Wear tests were performed using a pin-on-disc type wear testing device, under three different loads, at four different sliding distances in simulated body fluid environment. Results showed a decreasing powder size with increasing milling time. The highest decline in size occurred for the powders milled for 120 min. The result of hardness measurements and wear tests showed that samples milled for 120 min had both the highest hardness value and the lowest weight loss.Öğe Investigation of the Effect of Ni Amount on the Wear Performance of A356 Cast Aluminum Alloys(Springer, 2020) Simsek, I.; Simsek, D.; Ozyurek, D.This study investigates the effect of artificial aging treatment on wear performance of A356 alloy containing different amounts of Ni. Within the scope of the study, A356/Ni alloys were produced using the sand mold casting method and then the artificial aging treatment was applied. Alloys were naturally aged at room temperature for 24 hours and artificially aged at 170 degrees C for 10 hours after keeping in solid solution for 8 hours at 540 degrees C and rapidly cooling. The alloys produced were characterized with hardness and density measurements, microstructure examinations, and X-ray diffraction. Wear tests were performed using a pin-on-disc type testing device under three different loads and at four different sliding distances. It was found that alloy density increases with increasing Ni amount. The highest hardness value was obtained for 1% Ni added alloy, and an increase in hardness was observed with the addition of Ni. The lowest weight loss was obtained for 1% Ni added alloy, which also had the highest hardness, and it was observed that the addition of Ni led to an increase in weight loss.Öğe Investigation of Wear Performance of Different Amounts ZrO2 Reinforced Al-2Gr Matrix Composite Materials Produced by Mechanical Alloying Method(TUBITAK, 2019) Simsek, I.In this study, wear behavior of composite materials produced by adding different amounts of ZrO2 to Al-2Gr matrix by mechanical alloying method was investigated. After adding 2% (vol.) graphite to the aluminum matrix, 4 different amounts (3%, 6%, 9%, and 12%) of ZrO2 were added. The mechanically alloyed composite powders for 60 minutes were cold-pressed under 700 MPa pressure and green parts were produced. The green parts produced were sintered at 600 °C under argon for 120 minutes. The sintered ZrO2 reinforced aluminum composite materials (AMCs) are characterized by the scanning electron microscope, X-ray diffraction, and hardness and density measurements. Wear tests were performed on a standard pin-on-disc wear testing device with three different loads (10-20-30 N) at a sliding speed of 0.6 ms-1 and four different sliding distances (53, 72 and 94 m) according to ASTM G77 standard. As a result of the studies, the microhardness and density increases as the amount of ZrO2 in the composite material increases. As a result of the wear tests, the highest weight loss was obtained in the non-reinforced Al-2Gr matrix alloy, while the lowest weight loss was obtained in 12% ZrO2 reinforced composite materials. However, it was observed that there was a decrease in the friction coefficient with increasing amount of reinforcement. © 2019, TUBITAK. All rights reserved.
