Effect of Al-5Zr-1.1B Grain Refiner on Microstructure and Mechanical Properties of AZ91D Magnesium Alloy

Abstract:

An Al-5Zr-1.1B grain refiner was prepared by in-situ synthesis from Al melt and K₂ZrF₄+KBF₄ mixed powder. The microstructure of Al-5Zr-1.1B grain refiner was analyzed by XRD, SEM and EDS. The effect of Al-5Zr-1.1B grain refiner on the microstructure and mechanical properties of AZ91D magnesium alloy were studied. Results show that a large number of fine ZrB₂ particles were observed in the Al-5Zr-1.1B grain refiner and the ZrB₂ particles could act as the heterogeneous nuclei of α-Mg grains. With the increase of the addition amount of Al-5Zr-1.1B grain refiner, the α-Mg grains of AZ91D magnesium alloy were refined from coarse dendrites to equiaxed grains. When the addition amount of Al-5Zr-1.1B grain refiner increased to 0.6%, the α-Mg grains of AZ91D magnesium alloy were refined to fine equiaxed grains with an average diameter of 45 μm, and the tensile strength and elongation of AZ91D magnesium alloy were improved to 195.3 MPa and 3.94%, respectively. The α-Mg grains average diameter of AZ91D magnesium alloy decreased by 73.5% and the tensile strength and elongation improved by 25.9% and 27.9% compared with that of AZ91D magnesium alloy without adding the Al-5Zr-1.1B grain refiner. It is concluded that the Al-5Zr-1.1B is an effective grain refiner to refine the α-Mg grains of AZ91D magnesium alloy.

• Periodical: Materials Science Forum (Volume 816)
• Pages: 337-342
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.816.337
• Online since: April 2015
• Authors: Shun Cheng Wang*, Zheng Hua Huang, Wen Jun Qi, Kaihong Zheng
• Keywords: Al-Zr-B Grain Refiner, AZ91D Magnesium Alloy, Grain Refinement

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DOI: 10.1007/bf02642799