A First Report On Static Grain Growth Kinetics In An Ultralight Mg-8.41li-1.81al-1.77zn Alloy Subjected To Friction Stir Processing Volume 4 - Issue 5

Furong Cao¹*, Guoqiang Xue² and Bijin Zhou³

• ¹School of Materials Science and Engineering, Northeastern University, Shenyang 110819, PR China
• ²Xi’an Super crystal Science and Technology Development Co., Ltd., Xi’an 710016, PR China
• ³School of Mechanical Engineering, Suzhou University of Science and Technology, Suzhou 215009, PR China

Received: October 23, 2021;   Published: November 2, 2021

*Corresponding author: Furong Cao, School of Materials Science and Engineering, Northeastern University, Shenyang 110819, PR China

DOI: 10.32474/MAMS.2021.04.000198

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Abstract

Friction stir processing is one of the severe plastic deformation methods. Static grain growth study during friction stir processing does not receive enough attention compared to dynamic recrystallization study. Thus, in this report on static grain growth kinetics of Mg-Li alloy, an ultralight Mg-8.41Li-1.80Al-1.77Zn alloy has been fabricated by rolling, friction stir processing, and annealing. Microstructural examination of the nugget zone in the annealed state revealed that the grain growth rates at 523 and 573 K are much lower than the growth rate at 623 K. In the meantime, grain growth prior to 30 min is not obvious, but grains grow obviously with the increase in time after 30 min. The nugget zone grain growth kinetics equation abided by parabolic relation based on the linear fitting of the experimental grain sizes. The grain growth activation energy was 176.191 kJ/mol, higher than the lattice diffusion activation energy of magnesium, 135 kJ/mol. Probable cause is that the second phase particles increase the difficulty of thermal activation and raise the activation energy. The calculation error between theoretical grain growth model and experimental grain growth model is two orders of magnitude because of the use of an effective diffusivity. Hence, accurate theoretical model for static grain growth remains to be established in the future. This indirectly demonstrates the scientific meaning and value of established experimental parabolic growth model.

Keywords: Magnesium-lithium alloy; Friction stir processing; Annealing; Static grain growth; Microstructure

Abstract| Introduction| Experimental Procedures| Results and Discussion| Conclusion| Fund Projects| References|