2012م - 1444هـ
Magnesium Technology 2012: 1 The Effect of Precipitation on the Mechanical Properties of Extruded AZ80



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.



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.