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利用添加质量分数为0.4%的Al-Ti-B中间合金来改善Mg-20Al-0.8Zn镁合金的铸态组织,研究了该合金在半固态等温处理过程中的组织演变以及非枝晶组织的制备与控制。结果表明,Al-Ti-B能显著减小铸态Mg-20Al-0.8Zn合金的晶粒尺寸,且经过Al-Ti-B细化处理的Mg-20Al-0.8Zn合金在半固态等温热处理过程中可获得更加均匀、细小的球状固相颗粒,固相颗粒的粗化速度较慢。试验得到的半固态组织中固相颗粒的平均尺寸为55～65μm。试验表明,采用等温处理(450℃+保温90～120min;465℃+保温90min或485℃+保温60～90min)能够得到更适合触变成形的半固态浆料,其半固态浆料的组织更加均匀、晶粒更加细小。
The as-cast microstructure of Mg-20Al-0.8Zn magnesium alloy was improved by adding Al-Ti-B master alloy with mass fraction of 0.4%. The microstructure evolution and microstructure of the alloy during the semi- Preparation and control. The results show that the grain size of the as-cast Mg-20Al-0.8Zn alloy can be significantly reduced by Al-Ti-B, and the grain size of Mg-20Al-0.8Zn alloy refined by Al-Ti- The treatment process can be more uniform, small spherical solid particles, solid particles coarsening slower. The average size of the solid particles in the semi-solid microstructure tested was 55-65 μm. The results show that the semi-solid slurry more suitable for thixoforming can be obtained by isothermal treatment (450 ℃ + 90 ~ 120min; 465 ℃ + 90min or 485 ℃ + 60 ~ 90min) More uniform, the grain is more small.