تكنولوجيا المغنيسيوم والألمنيوم المؤتمر الوطني العراقي

سبائك المغنيسيوم والتكنولوجيا

تكنولوجيا المغنيسيوم وسبائكه وتطبيقاتها

المغنيسيوم وسبائكه تكنولوجيا وتطبيقات pdf

التكنولوجيا والمغنيسيوم

Abstract
The effect of ageing temperature and time on precipitates in AZ80
magnesium alloy were studied by optical microscopy to
investigate the influence on mechanical properties. The results
show the precipitation is distributed as bands along the extrusion
direction, with no twinning. After ageing, the precipitation
becomes dispersed uniformly. When ageing at 423 K,
discontinuous precipitated phase increases the yield and tensile
strength but reduces the ductility of the material. For ageing at 573
K, with increasing the ageing time, static ductility first increases
and then decreases. This means that recrystallization induced by
continuous precipitation is beneficial to both the strength and
ductility. However, the effect of age hardening under 573 K is not
better than 423 K. And {1012} < 1011 > twinning was also
activated in compression much more than in tensile samples,
which is consistent with the behaviour of AZ31.
Introduction
Magnesium alloys are considered as potential candidates for
numerous applications, especially in transportation vehicles or
lightweight enclosures for computer products owing to their
excellent properties, such as low density, high strength-to-weigh
ratios and high recycle-ability[l-2]. The Mg-Al-Zn is the most
widely used magnesium alloy at present. Some studies on AZ80
have been reported on its microstructure and mechanical
properties at different ageing temperatures [3-7]. However, the
AZ80 alloy still has some drawbacks, such as poor ductility, low
thermal conductivity and resistivity for example. The Mg-Al-Zn
alloy usually contains large amounts of a coarse and network
ß-Mg17Al12 as a divorced eutectic distributed along the grain
boundaries [8]. The network distributing of ß will restrict the
deformation and interfere with slip transfer. According to the

Orowan theory, the existing of ß phase which block the movement
of dislocation can change the critical resolved shear stress (CRSS)
of the slip systems. In the literature [9], it is considered that
continuous precipitation is responsible for most of the
age-hardening in Mg-Al-based alloys which is not the same as in
this study.
So to further understand this alloy, the objective of this work
is to investigate the effect of precipitation on the mechanical
properties of AZ80 and the microstructure present during the yield
stage to obtain a better understanding of how twinning affects
deformation.
Experimental
The material used in the present study was a commercial
AZ80 alloy with the measured composition (wt. %): 8.3A1, 0.6Zn,
0.5 Mn, 0.002 Cu, Mg (balance). The as-cast ingot was
homogenized at 683 K for 12h and extruded at 593 K with an
extrusion ratio of 8 and an extrusion rate 4.2 s"1

then air cooled. To
clarify the precipitation behavior of this alloy, the material was
then aged at either 423 K or 573 K for varying times. During
ageing, the ß phase precipitated out in two forms: discontinuous
and continuous precipitations. Mechanical tests were conducted at
room temperature with an initial strain rate of 2.67* 10"3
s"' on a
CSS-4410 testing machine. Optical microstructural
characterization was conducted using an OLYMPUS-BXD60M
microscope. Specimens for microstructure observation were
grinded and electrolytic polishing before etching for 5 s in a
solution of 5 ml acetic acid, 1.5 g picric acid, 10 ml distilled water
and 25ml ethanol.
Results and discussion
Figure 1 shows the as-extruded microstructure with no twinning
from a plane parallel to the extrusion direction (ED). During
deformation, the original grains are refined, and their boundaries
become serrated and in addition subgrains are formed.

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The Magnesium Technology Symposium, which takes place every year at the TMS Annual Meeting & Exhibition, is one of the largest yearly gatherings of magnesium specialists in the world. Papers are presented in all aspects of the field, ranging from primary production to applications to recycling. Moreover, papers explore everything from basic research findings to industrialization. Magnesium Technology 2011 covers a broad spectrum of current topics, including alloys and their properties; cast products and processing; wrought products and processing; forming, joining, and machining; corrosion and surface finishing; ecology; and structural applications. In addition, you'll find coverage of new and emerging applications in such areas as biomedicine and hydrogen storage.  
تعد ندوة تكنولوجيا المغنيسيوم ، التي تقام كل عام في الاجتماع والمعرض السنوي TMS ، واحدة من أكبر التجمعات السنوية لمتخصصي المغنيسيوم في العالم. يتم تقديم الأوراق في جميع جوانب المجال ، بدءًا من الإنتاج الأولي إلى التطبيقات إلى إعادة التدوير. علاوة على ذلك ، تستكشف الأوراق كل شيء من نتائج الأبحاث الأساسية إلى التصنيع. يغطي Magnesium Technology 2011 مجموعة واسعة من الموضوعات الحالية ، بما في ذلك السبائك وخصائصها ؛ منتجات الصب والمعالجة ؛ منتجات مشغولة ومعالجة؛ التشكيل والانضمام والتشغيل الآلي ؛ التآكل وتشطيب السطح ؛ علم البيئة. والتطبيقات الهيكلية. بالإضافة إلى ذلك ، ستجد تغطية للتطبيقات الجديدة والناشئة في مجالات مثل الطب الحيوي وتخزين الهيدروجين. 

Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (group 2, or alkaline earth metals) of the periodic table: all group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure.
المغنيسيوم هو عنصر كيميائي يحمل الرمز Mg والرقم الذري 12. وهو مادة صلبة رمادية لامعة تحمل تشابهًا ماديًا وثيقًا مع العناصر الخمسة الأخرى في العمود الثاني (المجموعة 2 ، أو معادن الأرض القلوية) من الجدول الدوري: الكل عناصر المجموعة 2 لها نفس التكوين الإلكتروني في غلاف الإلكترون الخارجي وبنية بلورية مماثلة.

Magnesium is the ninth most abundant element in the universe. It is produced in large, aging stars from the sequential addition of three helium nuclei to a carbon nucleus. When such stars explode as supernovas, much of the magnesium is expelled into the interstellar medium where it may recycle into new star systems. Magnesium is the eighth most abundant element in the Earth's crust and the fourth most common element in the Earth (after iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle. It is the third most abundant element dissolved in seawater, after sodium and chlorine.
المغنيسيوم هو تاسع أكثر العناصر وفرة في الكون. يتم إنتاجه في النجوم الكبيرة والشيخوخة من الإضافة المتسلسلة لثلاث نوى هيليوم إلى نواة الكربون. عندما تنفجر مثل هذه النجوم على شكل مستعرات عظمى ، يتم طرد الكثير من المغنيسيوم إلى الوسط بين النجوم حيث يمكن إعادة تدويره إلى أنظمة نجمية جديدة. يعد المغنيسيوم ثامن أكثر العناصر وفرة في القشرة الأرضية  ورابع أكثر العناصر شيوعًا في الأرض (بعد الحديد والأكسجين والسيليكون) ، ويشكل 13٪ من كتلة الكوكب وجزءًا كبيرًا من غطاء الكوكب. وهو ثالث أكثر العناصر المذابة وفرة في مياه البحر ، بعد الصوديوم والكلور.