Influence of Heat Treatment on Precipitation Behavior and Mechanical Properties of Extruded AZ80 Magnesium Alloy

By means of annular channel angular extrusion technology and solution treatment, the AZ80 supersaturated solid solution was prepared. The beta-Mg(17)Al(12)precipitate morphologies analysis along with its sizes and area fraction measurement was performed to investigate mechanical properties variation of alloy at various aging temperature. The results indicated that after solution treatment, the intergranular precipitate of as-extruded alloy was re-dissolved into the matrix, effectively decreasing the stress concentration, which was beneficial to the enhancement of elongation. At aging temperatures of 300 degrees C, Widmanstatten structure, lath-shaped precipitate, and intergranular precipitate were observed, while at 175-200 degrees C, cellular structure and oval-shaped particle were also identified. The morphology, area fraction, size of the precipitates, and PFZs (precipitate free zones) width worked together to affect the age-hardening behavior of the alloy. The strength and hardness of the peak-aged samples decreased with the increase in aging temperature, which is primarily attributed to the reduction in cellular structure area fraction and the corresponding increase in the interlamellar spacing, and the coarsening of the rhombus precipitate.

Automated summary

The study successfully prepared AZ80 supersaturated solid solution using annular channel angular extrusion technology, followed by investigation on mechanical properties variation at different aging temperatures. Results showed that precipitate morphology, size, area fraction, and PFZs width all played a role in affecting the age-hardening behavior of the alloy.