Influence of electromagnetic stirring on microstructure of AZ91-0.8%Ce magnesium alloy

Abstract

Effect of electromagnetic stirring on microstructure of AZ91-0.8%Ce magnesium alloy was investigated. The results show that electromagnetic stirring causes a change of morphology of α-Mg phase from coarse dendrites to fine rosette-like or spherical shape. Grain size is significantly refined within the range of input voltage 75–125 V, moreover, the optimum input voltage corresponded to the minimum value (64 μ m) of grain size is 125 V. Compared to the non-stirred condition, the amount of β-Mg₁₇Al₁₂ precipitate under the stirred condition obviously increases. The grain refinement of AZ91-0.8%Ce alloy is mainly attributed to multiplication of existing grains in the melt caused by forced fluid flow under electromagnetic stirring condition. Addition of 0.8% Ce results in the formation of ‘necking’ at secondary dendrite arm roots of α-Mg crystals, and consequently, it is helpful to increase the number of heterogeneous nucleation.

Keywords

AZ91 magnesium alloy / electromagnetic stirring / cerium / microstructure refinement