Effects of La on the Microstructures and Mechanical Properties of AZ91 Magnesium Alloy and its Mechanism

Abstract:

Microstructure changes brought by the addition of La element to AZ91 magnesium alloy are studied, also, the precipitating phases were identified and their influence on the mechanical properties of alloys was investigated. Results show La makes refinement of microstructure of the AZ91 alloy, and decrease the size of Mg₁₇Al₁₂ phase. La element takes a priority to react with Al element over Mg, forming binary phase Al₁₁La₃ with high melting point. Certain amount of La increases tensile strength, yield strength and elongation. With more addition, La would combine more Al in matrix and decrease strengthening effect, because Al₁₁La₃ phase would become coarsening. The mechanical poroerties tests indicate that AZ91+0.16%La alloy has the best properties. Maximum tensile strength, maximum yield strength and elongation are 245MPa, 178MPa and 14.5% respective, increased by 21%, 19% and 48% respectively. The mechanism of La strenthing mechanical properties is proposed that Al11La3 phase enriched on solid-liquid interface, increased the degree of supercooling, refined the grain size and changed the crystal style.

• Periodical: Advanced Materials Research (Volumes 328-330)
• Pages: 1650-1653
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.328-330.1650
• Online since: September 2011
• Authors: Jin Ling Zhang, She Bin Wang, Xiao Ye Qi, Bing She Xu
• Keywords: AZ91, Degree of Supcooling, Mechanical Property, Microstructure, Rare Earth La

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