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采用新型的自孕育法制备AZ91D镁合金半固态浆料,研究了导流器在半固态组织形成中的作用。结果表明,合金熔体加入孕育剂并经导流器浇注后,导流器吸收大量过热,使合金温度迅速降低至液相线附近;合金液在导流器表面流动时,导流器促进了熔体中非均质形核及游离晶粒的产生,使合金凝固时晶粒增殖。导流器表面凝固组织从上至下依次为树枝晶、细小树枝晶、等轴晶;倾斜角度影响合金流动方式及传热效果,角度过大和过小均不利于晶粒增殖,角度为45°时冷却效果和剪切作用最佳,此时合金有效形核数量最多,半固态浆料组织初生相细小且分布均匀。
The AZ91D magnesium alloy semi-solid slurry was prepared by a new self-inoculation method and the effect of the flow director on the semi-solid structure formation was studied. The results show that after the alloy melt is added into the inoculant and poured through the flow guide, the flow guide absorbs a large amount of overheating and the temperature of the alloy drops rapidly to the vicinity of the liquidus. When the alloy liquid flows on the flow guide surface, the flow guide promotes Heterogeneous nucleation and free grains in the melt result in grain growth during solidification of the alloy. The surface of the deflector solidified from top to bottom followed by dendrites, fine dendrites, equiaxed grains; tilt angle affect the alloy flow and heat transfer effect, the angle is too large and too small are not conducive to grain growth angle of 45 ° When the cooling effect and the shearing effect is the best, the number of the effective nucleation alloy is the most, the semi-solid slurry primary phase is fine and evenly distributed.