نویسندگان

دانشگاه صنعتی شریف، دانشکده مهندسی مواد، تهران، ایران.

چکیده

ورق آلومینیوم ۱۰۵۰ تغییر شکل شدید یافته تحت فرایند اصطکاکی اغتشاشی در شرایط مختلف فرآوری بدون نانوذرات در دمای اتاق و فرآوری به همراه نانوذرات در محیط نیتروژن مایع قرار گرفت. بررسی‌های ریزساختاری نشان داد که پس از سه پاس فرآوری، توزیع مناسبی از نانوذرات در منطقه اغتشاش یافته حاصل می‌شود. هم‌چنین مطالعات پراش الکترون‌های بازگشتی (EBSD) از منطقه مذکور مبین این مساله است که در مقایسه با نمونه تغییرشکل شدید یافته و فرآوری شده بدون نانوذرات و در دمای اتاق، فرآوری به همراه نانوذرات و در محیط نیتروژن مایع از وقوع رشد دانه شدید در منطقه اغتشاش یافته جلوگیری به‌عمل می‌آورد و ساختار بسیار ریزدانه حاصل می‌کند. به‌علاوه، استفاده از نانوذرات و محیط خنک‌کننده تغییری در جهت‌گیری ترجیحی دانه‌ها و سازوکار تبلور مجدد در منطقه اغتشاش یافته ایجاد نمی‌نماید. بررسی‌ها حاکی از آن است که سازوکار تبلور مجدد در منطقه اغتشاش یافته، بازیابی دینامیکی و تبلور مجدد دینامیکی پیوسته می‌باشد و در شرایط فرآوری در محیط نیتروژن مایع، تبلور مجدد دینامیکی ناپیوسته نیز به‌طور محدودی اتفاق می‌افتد. نتایج سختی‌سنجی نشان داد که استفاده هم‌زمان محیط خنک‌کننده و نانوذرات تأثیر چشمگیری بر بهبود خواص مکانیکی ناحیه اغتشاش یافته دارد.

کلیدواژه‌ها

عنوان مقاله [English]

The Effect of SiC Nanoparticles and Liquid Nitrogen Medium on Microstructure Evolutions of Severely Deformed Al During Friction Stir Processing

نویسندگان [English]

  • Mahmoud Sarkari Khorrami
  • Mohsen Kazeminezhad
  • Amir Hosein Kokabi

Sharif University of Technology, Department of Materials Science and Engineering, Tehran, Iran.

چکیده [English]

The severely deformed 1050-aluminum sheet was processed by friction stir processing (FSP) at different conditions of processing without nanoparticles in the ambient temperature and with SiC nanoparticles in the liquid Nitrogen medium. Microstructural assessments indicated that the appropriate distribution of SiC nanoparticles was obtained after 3-passes of FSP. In addition, electron backscattered diffraction (EBSD) analysis manifested that using nanoparticles along with the liquid Nitrogen medium during FSP was able to prevent the intense grain growth in the stir zone which occurred in the case of FSP without nanoparticles in the ambient temperature. Neither the orientation of grains nor the mechanism of grain formation in the stir zone was different comparing two mentioned FSP conditions. The mechanism of grain formation in the stir zone was determined to be dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX) phenomena. However, discontinuous dynamic recrystallization (DDRX) mechanism was also evident in the limited extent in the case of FSP with SiC nanoparticles in the liquid Nitrogen medium. The microhardness results showed that the simultaneous use of SiC nanoparticles and liquid Nitrogen medium during FSP caused to the significant improvement in the mechanical properties of the stir zone.

کلیدواژه‌ها [English]

  • Severe plastic deformation
  • Friction Stir Processing
  • SiC nanoparticles
  • Liquid Nitrogen
  • Recrystallization
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