中文摘要：

在消失模-熔模铸造AZ91D镁合金的凝固过程中施加机械振动,研究在不同浇注温度、振幅和振动频率下消失模-熔模铸造AZ91D镁合金组织的变化。结果表明,施加机械振动后获得组织中的树枝晶明显减少,随着浇注温度的降低镁合金组织逐渐被细化,但浇注温度过低不利于机械振动发挥最佳效果,在730℃时获得组织较为理想,晶粒主要呈等轴状。随着振动频率的增大,合金组织细化,当振动频率为100Hz时细化效果最好,初生α相的晶粒尺寸仅为166.4μm,β相也基本以细小颗粒状分布。增大振幅能使镁合金晶粒尺寸明显减小,在振幅为1.0mm时获得的晶粒最为细小、圆整。

英文摘要：

The mechanical vibration was applied on the AZ91 Dmagnesium alloy prepared by the expendable pattern shell casting,and effects of pouring temperature,vibration frequency and amplitude on microstructure of AZ91 D magnesium alloy prepared were investigated.The results show that the dendritic structure is reduced significantly by the mechanical vibration,and microstructure of AZ91 D magnesium alloy is refined with decreasing in the pouring temperatures,however,over-low pouring temperature is weaken to mechanical vibration to play the best effect,and a favourable microstructure of AZ91 D magnesium alloy can be observed at 730 ℃,and grains exhibit equiaxed structure.With the increase of vibration frequency,the microstructure of AZ91 D magnesium alloy is refined gradually.When the vibration frequency is 100 Hz,grain size of the primaryαphase is only 166.4μm,and theβphase is distributed in form of fine granular shape.The microstructure of AZ91 D magnesium alloy can be refined with the decrease of the vibration amplitude.When the amplitude is 1.0mm,the fine and spherical grain can be prepared.