RHEOLOGICAL BEHAVIOR OF SN-15 PCT PB IN CRYSTALLIZATION RANGE
RHEOLOGICAL BEHAVIOR OF SN-15 PCT PB IN CRYSTALLIZATION RANGE
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DOI：
10.1007/bf02642580
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发表时间：
1972-01-01
期刊：
影响因子：
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通讯作者：
MEHRABIAN, R
中科院分区：
文献类型：
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作者：
SPENCER, DB;FLEMINGS, MC;MEHRABIAN, R
用Couett型粘度计研究了Sn-15Pct铅合金在凝固范围内的流变行为。在剪切前部分凝固的样品中，变形是局部的，主要是沿晶的。固体分数大于0.15的样品有一个“表观屈服点”，约为每平方厘米106达因，并且随着固体分数的增加而增加。当合金从液相线上方冷却到所需的最终固体分数时，如果连续进行剪切，流动所需的剪应力将减少约三个数量级。固体-液体混合物现在表现为流体浆体。结构检查表明，剪切发生在样品的整个横截面上，固体以细颗粒悬浮液的形式存在。流动行为可以用粘度来描述，粘度依赖于固相分数，随着剪切速率的增加而减小，当剪切速率改变时表现出滞后现象。对于剪切速率为200s的−1，在固体分数为0.40时，粘度约为5泊泊，相当于常温下重质机械油的粘度。浆料在大比例固体中是高度流动的，这一事实表明在新的和现有的金属铸造工艺中有潜在的应用。
Rheological behavior of Sn-15 pct Pb alloy in the solidification range has been investigated using a Couette type viscometer. In samples partially solidified before shearing, deformation is localized and primarily intergranular. Samples containing more than about 0.15 fraction solid exhibit an “apparent yield point” which is on the order of 106dyne per sq cm and increases with increasing fraction solid. When shearing is conducted continuously while the alloy is cooled from above the liquidus to the desired final fraction solid, shear stresses required for flow are reduced by about three orders of magnitude. The solid-liquid mixture now behaves as a fluid slurry. Structural examination shows that shear takes place throughout the cross section of the specimen and that the solid is present as a fine grained particulate suspension. Flow behavior can be described by a viscosity which depends on fraction solid, decreases with increasing shear rate and exhibits hysteresis when shear rate is changed. For shear rates of 200 sec−1, at 0.40 fraction solid, viscosity is about 5 poise which is equivalent to that of heavy machine oil at room temperature. The fact that the slurry is highly fluid at large fractions solid suggests potential applications in new and existing metal casting processes.