سینتیک رشد دانه در آلیاژهای منیزیم حاوی آلومینیوم و عنصر نادر خاکی گادولینیم

نویسندگان

1 دانشگاه تهراندانشکده مهندسی متالورژی و مواد، دانشکده فنی، دانشگاه تهران

2 دانشکده مهندسی متالورژی و مواد، دانشکده فنی، دانشگاه تهران

چکیده

تحولات ریزساختاری در حین عملیات آنیل دمای بالا برای آلیاژهای منیزیم حاوی آلومینیوم و گادولینیمپس از فرایند اکستروژن مورد ارزیابی قرار گرفت و با آلیاژ 61AZ مقایسه شد. با قرارگیری آلیاژها در دمای بالا مشخص شد که حضور فاز Gdز3(Mg,Al)  که پس از اکستروژن به‌شکل ذرات ریز و پراکنده در ریزساختار قرار می‌گیرد اثر مثبتی بر جلوگیری از رشد دانه‌ها دارد. همچنین مشخص شد که ذرات Gd2 Al نمی‌توانند به شکل مؤثری جلوی رشد دانه را بگیرند. از طرف دیگر، رشد دانه در آلیاژ 61AZ به‌عنوان یک مشکل جدی مطرح شد که می‌تواند به‌دلیل حل شدن ذرات بین فلزی 12Al 17Mg در دماهای بالاتر از 300 درجه سانتی‌گراد باشد. در آلیاژهای منیزیم حاوی آلومینیوم و گادولینیم، بهبود پایداری آلیاژ در دمای بالا دیده شد که به افزایش دمای ذوب نسبت داده شد. درنهایت، رشد دانه غیریکنواخت در حضور ذرات Al2Gd مشاهده شد که به اثر پین‌کنندگی غیریکنواخت مرزدانه‌ها توسط این ترکیب بین فلزی مرتبط شد.

کلیدواژه‌ها

عنوان مقاله [English]

Grain Growth Kinetics of Magnesium Alloys Containing Aluminum and Rare-Earth Element Gadolinium

نویسندگان [English]

  • B. Pourbahari 1
  • H. Mirzadeh 2
  • M. Emamy 2
1 School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Iran.
2 School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Iran.
چکیده [English]

Microstructural evolutions during the high-temperature annealing of Mg alloys containing Al and Gd and after the extrusion process were evaluated and compared to those of the AZ61 alloy. It was revealed that during exposure at the elevated temperatures, the presence of (Mg,Al)3Gd phase, in the form of fine and dispersed particles in the matrix after the extrusion process, could be favorable for the inhibition of grain growth. It was also found that the Al2Gd particles could not effectively retard the coarsening of grains. On the other hand, the grain growth of AZ61 alloy was found to be problematic, which was related to the dissolution of the Mg17Al12 intermetallic phase at temperatures higher than 300°C. In the Mg alloys containing both Al and Gd elements, the increased thermal stability was observed, which was ascribed to the rise of the melting temperature. Finally, some abnormal grain growth was observed in the presence of Al2Gd phase, which was attributed to the nonuniform pinning of grain boundaries by this intermetallic compound.
 

کلیدواژه‌ها [English]

  • Magnesium alloys
  • Rare-earth elements
  • microstructure
  • Grain growth kinetics

مراجع

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مواد پیشرفته در مهندسی
دوره 37، شماره 4
اسفند 1397
صفحه 1-11

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