Title: Precipitation and recrystallization in two Al-4.5% Mg-Mn alloys

Authors: Sheng-Long Lee, Yeon-Sheng Yang

Addresses: Department of Mechanical Engineering, National Central University, Chungli, Taiwan 32054, Republic of China. ' Department of Mechanical Engineering, National Central University, Chungli, Taiwan 32054, Republic of China

Abstract: A study was made of the correlation between the microstructure of Al-Mg with different quantities of the element Mn in the annealing treatment after different amounts of cold working. The results show that the amount of cold working, the annealing temperature, and the content of Mn element in the A1-4.5% Mg-Mn alloys all affect primary recrystallization. From TEM, it can be seen that dispersoid particles of MnA14 were precipitated on the intradendrites after homogenization. These dispersoid particles can promote recrystallization by providing a recrystallization nucleation site. In addition, they also have the effect of restricting the growth of recrystallized grains, preventing them from becoming too coarse. However, if the alloys are subjected to protracted annealing at high temperature, the grain will become abnormally coarse. It was also found that the recrystallization rate of these alloys matches the Arrhenius-type law. The activation energy of recrystallization decreases as the quantity of the element Mn and the amount of cold working increase.

Keywords: Al-Mg-Mn alloys; aluminium alloys; cold working; MnAl4; particles; microstructure; recrystallized grains; precipitation; magnesium; manganese; annealing.

DOI: 10.1504/IJMPT.1993.036525

International Journal of Materials and Product Technology, 1993 Vol.8 No.1, pp.71 - 77

Available online: 04 Nov 2010

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