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针对半固态成形中需要具有细小颗粒均匀分布的非枝晶坯料以获得流变特性,采用控制形核的方法,制备了具有触变特性的半固态坯料.亚共晶Al—Si合金以不同的浇注温度浇注到永久模中,随着浇注温度的增加,晶粒尺寸和形状成柱状晶的趋势增加.带有金属丝网的试验表明,低温浇注时型壁形核机理起重要作用.675℃以下浇注时,型壁形核的生存率决定了最终结构, 包括晶粒尺寸和形貌;浇注温度高于675℃时,其他的形核机理起决定作用.
In order to obtain the rheological properties of non-dendritic billets with uniform distribution of fine particles in semi-solid forming, semi-solid billets with thixotropic properties were prepared by controlled nucleation method.The hypoeutectic Al-Si alloys with different Pouring temperature is poured into the permanent mold, with the pouring temperature increases, the grain size and shape of the columnar crystal tendency to increase with a wire mesh test shows that the type of walled nucleation mechanism plays an important role at low temperature .675 ℃ The survival rate of the wall nucleation determines the final structure, including grain size and morphology, at the following pouring; other nucleation mechanisms play a decisive role at pouring temperatures above 675 ° C.