机械研磨工艺对AZ91D镁合金显微结构的影响

Effects of Surface Mechanical Attrition Treatment Technique on Microstructure of AZ91D Magnesium Alloys

目的研究不同机械研磨处理条件对AZ91D镁合金表面晶粒细化行为与机制的影响。方法采用不同直径的弹丸对密排六方结构的AZ91D镁合金进行不同时间的表面机械研磨处理,对处理试样的表面显微结构进行对比和表征,分析晶粒细化机制。结果通过表面机械研磨处理可以实现AZ91D镁合金的表层晶粒细化。在一定范围内,弹丸直径越大,处理时间越长,表层晶粒细化就越明显,晶粒尺寸可细化至约24 nm。结论 AZ91D镁合金表面机械研磨处理晶粒细化是孪生和位错滑移的综合结果。选择弹丸直径16 mm,处理时间180 min的工艺参数,AZ91D镁合金表面机械研磨处理的效果最好。

Objective To investigate the influence of surface mechanical attrition treatment technique on the grain refinement behavior and mechanism of AZ91 D magnesium alloys. Methods The AZ91 D magnesium alloy in hexagonal-closet-packet structure was treated by surface mechanical attrition treatment（ SMAT） with different ball diameters and handling time,and the microstructure of surface deformed layer was characterized and compared. Results The grain of AZ91 D magnesium alloys was obviously refined by surface mechanical attrition treatment. In a certain range,as the balls diameter or handling time increased,the grain size became smaller,and could finally reach about 24 nm. Conclusion The grain refinement mechanism of AZ91 D magnesium alloy by surface mechanical attrition treatment was the results of twinning and dislocation slip. When the diameter of balls was 16 mm and the handling time was 180 min,surface mechanical attrition treatment has the highest efficiency.