بررسی رفتار کارگرم آلیاژ Mg-10Li-1Zn توسط معادلات ساختاری آرنیوسی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 کارشناسی ارشد دانشکده مهندسی متالورژی و مواد دانشگاه تهران

2 استادیار دانشکده مهندسی متالورژی و مواد دانشگاه تهران

3 استاد دانشکده مهندسی متالورژی و مواد دانشگاه تهران

چکیده

در این پژوهش رفتار تغییر شکل فشاری گرم آلیاژ اکسترود شده Mg–10Li–1Zn با استفاده از آزمون فشار در محدوده ی دمایی 450-250 درجه سانتیگراد و محدوده ی نرخ کرنش 1/0-001/0 بر ثانیه مورد مطالعه قرار گرفت. در حین تغییر شکل فشاری گرم آلیاژ Mg–10Li–1Zn نمودار تنش سیلان به یک حد بیشینه رسیده و پس از آن به حالت پایدار می‌رسد که نشاندهنده وقوع تبلور مجدد دینامیکی است. این حالت در دماهای پایین تر و نرخ کرنش های بالاتر مشهودتر است. به دلیل آنکه در دماهای بالاتر و نرخ کرنش‌های پایین‌تر مکانیزم‌های نرم‌شوندگی بیشتر فعال می‌شوند.
رفتار سیلان آلیاژ Mg–10 Li–1 Zn در دماهای بالا توسط معادلات ساختاری آرنیوسی مدل سازی شد. مقادیر انرژی فعالسازی 103 کیلوژول بر مول و نمای تنشی قانون توانی 0/6- 2/5 حاصل از معادلات آرنیوسی نشاندهنده ی این موضوع است که مکانیزم غالب تغییر شکل گرم آلیاژ، صعود نابجایی ها کنترل شده با نفوذ درخود شبکه ای لیتیم می باشد.

کلیدواژه‌ها


عنوان مقاله [English]

The study of hot deformation behavior of an Mg-10Li-1Zn alloy by Arrhenius constitutive equations

نویسندگان [English]

  • Mostafa Shalbafi 1
  • Reza Roumina 2
  • Reza Mahmudi 3
1 M.Sc., School of Metallurgy and Materials Engineering, Tehran University,
2 Assistant Professor, School of Metallurgy and Materials Engineering, Tehran University
3 Professor, School of Metallurgy and Materials Engineering, Tehran University,
چکیده [English]

Hot deformation of an extruded Mg–10Li–1Zn alloy was studied by compression testing in the temperatures range of 250- 450 ˚C and strain rates of 0.001–0.1 s−1. During the hot compressive deformation of the Mg-10Li-1Zn alloy, flow stress curves reach a maximum value and then reach a steady state which is indicative of the occurrence of dynamic recrystallization. Because of the activation of softening mechanisms at higher temperatures and lower strain rates, this phenomenon is more pronounced at lower temperatures and higher strain rate.
The flow stress of the Mg–10Li–1Zn alloy at elevated temperatures was modeled via an Arrhenius-type constitutive equation. The values for the activation energy of about
103 kJ mol–1 and the power-law stress exponents in the range of 5.2–6.0 obtained from the Arrhenius-type model indicate that the dominant mechanism during hot deformation of the Mg–10Li–1Zn alloy is dislocation climb which is controlled by the lattice
self-diffusion of Li atoms.

کلیدواژه‌ها [English]

  • Mg-Li alloys
  • Hot deformation
  • Constitutive equations
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