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利用超声振动法制备AZ91合金半固态浆料,在不同温度区间和冷却速率下对熔体进行超声处理,研究冷却条件对AZ91半固态浆料微观组织的影响。结果表明:在形核阶段,熔体在超声振动引发的空化和声流效应作用下,能够获得细小、近球状的初生α-Mg固相颗粒;在固液相线温度区间内,随着超声温度下限的降低,半固态浆料的固相率和固相颗粒的平均尺寸增加;在超声振动过程中,随着冷却速率的提高,半固态浆料的固相率增大,固相颗粒的平均形状因子降低。在本实验条件下,适宜的超声振动温度区间为605°C到595°C或590°C,合适的冷却速率为2~3°C/min。
The AZ91 alloy semi-solid slurry was prepared by ultrasonic vibration method. The melt was sonicated at different temperature range and cooling rate to study the effect of cooling conditions on the microstructure of AZ91 semi-solid slurry. The results show that in the nucleation stage, the fine and nearly spherical primary α-Mg particles can be obtained under the action of cavitation and acoustic flow caused by ultrasonic vibration. In the solid-liquid line temperature range, The lower the ultrasonic temperature lower limit, the solid fraction of semi-solid slurry and the average size of solid particles increase; in the ultrasonic vibration process, with the increase of cooling rate, the solid fraction of semi-solid slurry increases, The average shape factor decreased. Under the experimental conditions, suitable ultrasonic vibration temperature range of 605 ° C to 595 ° C or 590 ° C, the appropriate cooling rate of 2 ~ 3 ° C / min.