摘要
文章研究了用同轴双筒流变仪测定在 Couette 剪切流动中Sn-15％Pb 合金部分凝固时的流交性质。结果表明:当固相分数接近极限固相分数时,半固态浆液具有宾汉流体的流变学特征:宾汉屈服现象和剪切应力与切变速率曲线线性化。这是由于固相颗粒形成了不连续网。而当浆液中固相分数较低时,它的流变性更象假塑性流体。研究发现:在一定的剪切条件下,固相颗粒不是彼此分离的,而是存在聚集。在等温剪切流动中固相颗粒群的形成与崩溃,对部分凝固合金的流变性质有重要影响。
The theological features of partially solidified Sn-15% Pb alloy in Couette shear flow have been studied by using a concentric cylinder viscometer. The results show that when the volume fraction of the primary solid approaches to its limit value, the semi-solib slurry is of Bingham fluid characteristies, i. e. there exists Bingham yielding and a linear relationship between the shear stress and shear rate. This is attributed to the formation of discontinous networks of solid particles. However, when the slurry has lower solid volume fraction, the theological behavior is more like that of a pseuooplastic fluid. It is found that under certain shearing conditions solid partidles are not separated from each other, but become aggregated. The formation or collapse of the aggregates in the isothermal shear flow affects the theological features of partially solibified alloys significantly.
