高能超声与稀土钇复合作用对AZ91铸态组织的影响

Effect of Addition of Y with Ultrasonic Field Assistance on as-Cast Microstructure of AZ91 Alloy

摘要:

以AZ91-Y为反应体系，对熔体施加高能超声，利用Miedema混合焓模型预测了合金析出相主要为Al-Y金属间化合物，结合X射线衍射结果, 表明析出相为Al2Y。对材料显微组织形貌分析，结果表明: 不施加超声，稀土Y加入量超过1.0%(质量分数)时，析出相Al2Y逐渐长大并团聚，晶粒细化效果不明显；当在850 ℃对AZ91-Y熔体超声2 min后，Al2Y颗粒变细，分布均匀，材料组织中的β相Mg17Al12由连续状变为断续状或颗粒状，晶粒变小，材料的显微组织明显细化

Abstract:

The effects of addition of Y with ultrasonic field assistance on as-cast microstructure of AZ91 alloy were studied. The predominant precipitated phases of AZ91-Y alloy system were worked out to be Al-Y intermetallics by Miedema’s model, and the new precipitated phases were verified to be Al2Y by the result of XRD. The phases and microstructure of the composites were also analyzed. The result shows that when the content of Y in AZ91 alloy exceeds 1.0%, the precipitated phases Al2Y grow up and agglomerate gradually, the grain refinement effect is not obvious. After the AZ91-Y melt are treated by ultrasonic for 2 min at 850 °C, Al2Y particles are refined and distribute uniformly, and the morphology of β-Mg17Al12 changes from continuous to discontinuous or spherical morphology, while the grain and microstructure of the alloy are refined obviously