Effect of cooling rate on microstructure and compressive performance of AZ91 magnesium alloy
(1.辽宁省沈阳市沈阳工业大学材料科学与工程学院
2.School of Materials Science and Engineering, Shenyang University of Technology,Shenyang 110023, China)
2.School of Materials Science and Engineering, Shenyang University of Technology,Shenyang 110023, China)
Abstract: Effect of cooling rate on both microstructure and room temperature compressive performance of the AZ91 magnesium alloy was investigated. The experimental results show that with increasing cooling rate, the quantity of the solid solution phase increases and the fraction of secondary phase Mg17Al12 decreases. The almost single solid solution phase can be obtained with using liquid nitrogen as a coolant. The compressive strengths of the rapid solidified AZ91 magnesium alloys are higher than those of normal cast alloy, and decrease with increasing cooling rate. After artificial aging treatment for 14 h at 168 ℃, the compressive strength of the rapidly solidified AZ91 magnesium alloy cooled in liquid nitrogen increases from 253.5 to 335.3 MPa, while the compressive yield strength increases from 138.1 to 225.91 MPa. The improvement in the compressive strength of the rapidly solidified AZ91magnesium alloys can be attributed to the hardening effect from fine secondary phase.
Key words: magnesium alloy; cooling rate; microstructure, compressive performance