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以AZ91D镁合金为试验材料,采用双螺旋半固态浆料制备装置,研究了在液相线附近施加不同搅拌速度时,镁合金熔体凝固过程中非枝晶组织的形成机理及演变特征。结果表明:搅拌温度为605℃,搅拌速度950 r/min时,坯料组织中初生α-Mg变得细小圆整,主要以球状晶为主,由于强烈的搅拌使得熔体内部温度场与浓度场均匀,有利于晶核生长成球状;搅拌温度为590℃时,在较低的搅拌速度下就可以观察到球状初生α-Mg晶粒,且随着搅拌速度的提高,组织中初生α-Mg数量增多,晶粒逐渐变得细小、圆整,主要由于搅拌速度的增大对球晶的生长起到了抑制作用。
Using AZ91D magnesium alloy as experimental materials, the formation mechanism and evolution characteristics of non-dendritic structure during the solidification of magnesium alloy melt were studied by using a twin-screw semi-solid slurry preparation device with different stirring speeds. The results showed that the primary α-Mg became fine and round when the stirring temperature was 605 ℃ and the stirring speed was 950 r / min. The main spheroidal crystals were spherulites. Due to the strong stirring, the internal temperature field and the concentration field Uniform and conducive to the growth of the nucleus into a spherical shape; stirring temperature of 590 ℃, at a lower stirring speed can be observed spherical primary α-Mg grains, and with the stirring speed, the organization primary α-Mg Increasing the number of grains gradually become small, round, mainly due to the stirring speed increases the growth of spherulites played a restraining effect.