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采用自行研制的流变装置进行瞬态流变试验 ,研究了剪切停留对液固温区 A35 6合金初生 α相聚合重构过程及其瞬态流变行为的影响。结果表明 ,随剪切停留时间的增加 ,瞬时峰值表观粘度增加 ,说明剪切停留期间半固态合金初生α相逐渐聚合重构。通过半固态合金初生α相的形态观察可知 ,剪切停留促使初生α相发生了“团聚”或“合并”,而且初生α相形态变化的程度取决于剪切停留时间和初生α相的退化程度。以试验结果为依据 ,借助反应动力学原理推导出描述半固态合金峰值表观粘度与停留时间关系的瞬态流变方程 ,为描述半固态合金在成形过程中的流变特征提供了理论依据
The transient rheological tests were carried out with a rheometer which was developed by ourselves. The influence of shear residence on the rheological behavior and rheological behavior of primary α-phase polymerization of A356 alloy in liquid-solidified zone was studied. The results show that with the increase of shear residence time, the apparent viscosity of instantaneous peak increases, which indicates that the primary α phase of semisolid alloy gradually polymerizes and remodels during the shear residence. According to the morphological observation of the primary α phase in the semi-solid alloy, the primary residence of α causes “agglomeration” or “consolidation” of the primary α phase, and the degree of primary α phase change depends on the shear residence time and the degree of degeneration of the primary α phase . Based on the experimental results, a transient rheological equation describing the relationship between peak apparent viscosity of semi-solid alloy and residence time was deduced by means of reaction kinetics, which provided a theoretical basis for describing the rheological characteristics of semi-solid alloy in the forming process