Evolution of non-dendrite microstructure of Mg-xZn-0.3La-0.3Si magnesium alloy

Abstract

Abstract: The Mg-9Zn-0.3La-0.3Si alloy was subjected to isothermal heat treatment at different temperatures and different durations, and the influence of holding temperature and holding time on the evolution of non-dendritic structure in Mg-9Zn-0.3La-0.3Si alloy were studied. The formation mechanism of non-dendritic grains was also analyzed. The experimental results showed that isothermal heat treatment can transform the as-cast dendritic structure of Mg-9Zn-0.3La-0.3Si alloy into spherical non-dendritic grain structure. The ideal non-dendritic structure is obtained at a holding temperature of 585 ℃ for 30 minutes, with a solid-phase fraction, shape factor, and average grain size of 74%, 1.32, and 63.59 μm, respectively. With the extension of holding time or the increase of holding temperature, the average size and shape factor of non-dendritic grains first decrease and then increase, while the solid-phase fraction of non-dendritic structure continues to decrease. The evolution of non-dendritic structure mainly includes three stages: initial coarsening, dendrite melting and grain spheroidization, grain coalescence and maturation.

Key words: Mg-Zn-La-Si magnesium alloy, semi-solid state, isothermal heat treatment

CLC Number:

TG146.2

HUANG Xiao-feng, HE Guang-liang, CHEN Xuan-yu ZHANG Xin-tao, TAO Wei, HE Dan-dan. Evolution of non-dendrite microstructure of Mg-xZn-0.3La-0.3Si magnesium alloy[J]. Journal of Lanzhou University of Technology, 2025, 51(3): 1-8.

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