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    The effect of allotropic transformation temperature in diffusion-welded low-carbon steel and copper
    (Natl Acad Sciences Ukraine, Inst Metal Physics, 2006) Kurt, Adem; Uygur, İlyas; Mutlu, Ekrem
    Diffusion welding (DW) is a solid-state joining process, capable of joining a wide range of metal and ceramic combinations to produce both small and large components. In this study, low-carbon steel (AISI 1010) was joined to commercially pure copper by diffusion welding technique. Metallographic and mechanical examinations were carried out to determine the welding quality. Diffusion interfaces were investigated by scanning electron microscopy (SEM) and x-ray energy-dispersive spectroscopy (EDS) analysis in order to observe the effect of allotropic-transformation temperature on the amount of diffusing elements. It was found that Fe diffusion from AISI 1010 steel to copper at the transformation temperature of 845 degrees C was lower than the measurement at 770 degrees C. This low-diffusion amount at 845 degrees C was attributed to the consumption of the internal energy for the phase transformation. From the findings of this study, it can be concluded that the perfect diffusion welding can be done in the temperature just below the allotropic transformation. The shear strength in DW joints was also evaluated.
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    Effect of porosity content on the weldability of powder metal parts produced by friction stir welding
    (Trans Tech Publications Ltd, 2007) Kurt, Adem; Uygur, İlyas; Ateş, Hakan
    Friction stir welding technique (FSW) has many advantages in terms of tool design, rotational speed and traveling speed, and can be adjusted in a precise manner. It enables heat input into the system to be controlled. In this study, Aluminum powders were compacted at 350,400 and 450 MPa pressure and sintered at 450 degrees C temperature for 30 minutes in Ar atmosphere. Sintered powder metal parts were joined to each other by FSW at the speed of 1800 rpm and traveling welding speed 200 mm/min under a constant friction force. The results show that the amount of porosity affects the welclability of powder metallurgy (P/M) parts. Furthermore, the porosity and microstructural evolution of the Aluminum also affected the hardness values of the tested materials.
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    Effects of isoflurane on postoperative olfactory memory
    (Carbone Editore, 2014) Bilgi, Murat; Demirhan, Abdullah; Akkaya, Akcan; Tekelioğlu, Ümit Yaşar; Erdem, Kemalettin; Apuhan, Tayfun; Kurt, Adem
    Purpose: In this study, we planned to investigate the effects of isoflurane 1.2%, on olfactory memory. Methods: This is a prospective clinical study conducted over 40 patients aged 18-50 who had elective surgery and American Society of Anesthesiologists (ASA) physical status I-II. The Brief Smell Identification Test (BSIT) was used for interpreting patients' olfactory memories before and after the surgical procedure. Patients received standard general anesthesia protocol and routine monitoring. For induction, 1.5 mg/kg of fentanyl, 2 mg/kg of propofol, and 0.5 mg/kg of rocuronium bromide were administered. Anesthesia was maintained with the inhalational of anesthetic isofluraine (1.2%). The scores are recorded 30 minute before the surgery and when the Aldrate Recovery Score reached 10 in the postoperative period. Preoperative and postoperative results were compared and p-values <0.05 were considered statistically significant. Results: The patients' mean age were 38.4 +/- 13.8. Preoperative total correct answer rate to odorous substances was 91.4%, and postoperative rate was 90.8%. Percentage of the odor substance identification by the patients revealed no statistically significant difference when pre and post-operative rates have been compared. (P>0.05) Conclusion: In conclusion, it is the first time we demonstrate general anesthesia with isoflurane 1.2 % has no significant effect on the olfactory memory. Further studies with larger samples will be required to confirm our findings.
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    Effects of temperature on the weldability of powder metal parts joined by diffusion welding
    (Trans Tech Publications Ltd, 2007) Kurt, Adem; Uygur, İlyas; Ateş, Hakan
    Diffusion welding is an advanced bonding process in which similar or dissimilar materials can be bonded in solid state. In this study, aluminium composite (5% and 15% WC) powders were compacted at 450 MPa pressure and sintered at 550 degrees C for 45 minutes in argon atmosphere.and joined each other by diffusion bonding. The bonding temperatures (585 degrees C, 600 degrees C, 615 degrees C) and dwell time (185 min) were chosen for the welding process at constant 20 MPa. It has been observed that these variations on the welding parameter strongly affected the microstructure and the weldability of the materials.