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Article
Study of the Direct Extrusion Behavior of Aluminum and Aluminum Alloy-2014 Using Conical Dies
دراسة سلوك البثق المباشر للألمنيوم وسبيكة الألمنيوم - 2014 بإستخدام قوالب مخروطية

Authors: Ahmed A. Akbar --- Rabiha S. Yaseen
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2012 Volume: 30 Issue: 6 Pages: 950-958
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The present work concerns with study of extrusion behavior of aluminum alloy-Al2014 comparing with pure aluminum-Al1050, using different die angles (á=15, 30 and 75°) and different billet lengths (20, 28, 40 and 52mm). Results showed that the extrusion load increase when billet length increases for aluminum alloy (Al-2014) and pure aluminum (Al-1050). The results also showed that small die angles required higher extrusion load than large die angles. The Brinell hardness values showed that aluminum alloy (Al-2014) undergoes higher workhardening due to the presence of copper compared with the pure aluminum (Al-1050), in addition to formation of dead metal zone which resists the metal flow through the die opening.


Article
Fracture Toughness and Micro-Strain of Y-TZP Nanoceramics at Different Sintering Temperature

Authors: Rabiha S. Yaseen --- Leena M. Kalifa
Journal: Journal of University of Babylon مجلة جامعة بابل ISSN: 19920652 23128135 Year: 2018 Volume: 26 Issue: 1 Pages: 205-220
Publisher: Babylon University جامعة بابل

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Abstract

The objective of this research is to study the effect of sintering temperature on the mechanical properties and micro-strain of yttria tetragonal zirconia polycrystalls (Y-TZP) nanostructure. Where green disk formed by uniaxially press, sintered at (1500 – 1550 – 1600⁰C) in air for 2hr then polished to mirror shape for fracture toughness and micro-hardness measurement by Vickers indenter at (60 kg to 100gm) loads. Atomic force microscopy (AFM) technique was use to measure the change in grain size and shape of the samples, X-ray diffraction (XRD) evaluated to identify the phases and to measure the micro-strain of the samples. The Results show that increasing sintering temperature will increase the grain size with increasing the average of micro-strain. Tetragonal phase is the prevailing phase with small amount of cubic phase and the amount of monoclinic phase was under detection limite after sintering but there is increas in lattice dimension according to micro-strain calculation and grinding process produce micro-strain. With increasing the sintering temperature micro-hardness and fracture toughness will increas

الهدف من هذا البحث هو دراسة تاثير درجة حرارة التلبيد على الخواص الميكانيكية و الانفعال المرن للزركونيا المثبتة باليتريا النانوية. حيث تم تلبيد العينات المكبوسة عند درجات (1500 – 1550 – 1600م⁰) في الهواء لمدة ساعتين , ثم بعد التلبيد تم صقلها لغرض اجراء فحص الصلادة المايكروية و لفحص متانة الكسر بواسطة جهاز فكرز (من 60 كغم الى 100غم). تم استخدام جهاز المجهر الذري لايجاد التغير في حجم و شكل الحبيبات في العينات , و تم فحصها بواسطة الاشعة السينية لتحديد نوع الطور الناتج و لتحديد قيمة الانفعال المايكروي للعينات. لقد بينت النتائج انه عند زيادة درجة التلبيد سوف يزداد الحجم الحبيبي مع زيادة الانفعال المايكروي. ان الطور السائد الناتج بعد التلبيد هو الطورالرباعي , مع زيادة ابعاد المشبك نتيجة للانفعال المرن , و مع زيادة درجة التلبيد تزداد الصلادة المايكروية مع زيادة متانة الكسر.


Article
Study the Effects of Squeeze Casting Parameters on the Corrosion Behavior of Al-Si-4Cu Alloy

Authors: Rabiha S. Yaseen --- Hussein A. Hussein --- Amjad H. Jassim
Journal: Journal of University of Babylon مجلة جامعة بابل ISSN: 19920652 23128135 Year: 2015 Volume: 23 Issue: 3 Pages: 558-570
Publisher: Babylon University جامعة بابل

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Abstract

This study investigated the effects of squeeze parameters on the properties of squeeze castings and the optimum parameters for producing squeeze castings from Al-Si alloy. It also compared the properties of the squeeze castings with those of gravity castings. Squeeze castings were made from Al-Si-4Cu alloy using pressures of 10,15,20,25 and 30 MPa with the alloy poured at 750, 800 and 850oC into a die preheated to 300oC. Squeeze time was 30s. The corrosion experiments were performed over a range of elevated pressure, pouring temperature and were carried out in sea water (3.5% NaCl solution). We have focused to determination of the rate of corrosion and other corrosion characteristics. Both as-gravity cast and squeeze specimens were tested, for comparison. Corrosion behavior of the materials was assessed by the corrosion potential by potentiostate (polarization) curves. It was found that for a specific pouring temperature,microstructure of squeeze castings became finer;mechanical properties were increased with increase in pressure to their maximum values. Compared with gravity casting process, squeeze casting enhanced the mechanical properties; it increased the hardness from Hv 18.083 Kg for gravity castings to a maximum of Hv 35.413 for squeeze castings which constitutes about 50.063% increase over those of gravity castings. Although squeeze casting parameter has decreased the corrosion current density (of about 2 μAcm2) when compared to the results of the as-cast samples

في هذا البحث تم دراسة متغيرات السباكة بالعصر على خواص المسبوكات لتحديد المتغيرات المثلى لانتاج سبيكة المنيوم نحاس سليكون وكذلك مقارنة خواص السباكة بالعصر مع خواص السباكة التقليدية. المتغيرات المستخدمة في سباكة العصر لسبيكة الالمنيوم نحاس سليكون, الضغط المستخدم 30,25,20,15,10 Mpa ودرجة حرارة صب 850,800,750 درجة مئوية, مع تسخين مسبق للقالب الى cº300 وزمن الضغط 30 ثانية. استخدمت تجارب التاكل في ماء البحر بتركيز 3.5% NaCl. تم حساب سلوك التاكل للسبيكة بواسطة المجهاد الساكن (منحنيات الاستقطاب) حيث وجد ان الخواص الميكانيكية ومقاومة التاكل تزداد مع زيادة درجة حرارة الصب والضغط, حيث اصبحت البنية المجهرية دقيقة وازدادت الخواص الميكانيكية مقارنتا بالسباعة التقليدية. حيث ان صلادة فيكرز 18.083 للسبيكة التقليدية و 35.413 للسباكة بالعصر, الزيادة تقريبا 50.63 حيث ان متغيرات السباكة بالعصر قللت كثافة تيار التاكل 2 mAp مقارنة بالسباكة التقليدية.


Article
MICROSTRUCTURE AND MECHANICAL PROPERTIES OF HOMOGENIZED STIR CASTING ALUMINUM BRONZE ALLOYS

Authors: Sami Abualnoun Ajeel --- Rabiha S. Yaseen --- Asaad Kadhim Eqal
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2018 Volume: 11 Issue: 3 Pages: 345-356
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

In demand to the industrial needs to produce Cu-Al alloys with controlled chemical compositions. The present research focuses on the production of Cu-Al alloys with different aluminum additions of 1.9, 3.6, 5.8 and 7.7 wt. % by stir casting method in argon atmosphere. Then, homogenized treatment was done for these alloys at 850 oC in different periods of soaking time of 2, 4, and 6 hrs to determine the best conditions for increasing the mechanical properties. This is carried out in the α phase region. The microstructure of the samples is analyzed by using Optical and Scanning Electron Microscopy (SEM) with (EDS). The results showed the mechanical properties of copper were increased with increasing in Aluminum content. The microstructure of the castings consist of the dendiritic structure, columinar grains and segregation. The results showed that after homogenization, the microstructure changed to fine grains, elimination of the columnar segregation and the clusters disappeared. The XRD results show that the phases are α (Cu-rich) phase as highest peaks and the small amount of CuAl2 phase. The best Aluminum content value was 7.7 wt % and the soaking time 4 hrs were given the high hardness 204 Hv and the highest ultimate tensile stress value of 383.8 Mpa

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