论文部分内容阅读
利用自制的小型单晶连铸设备，成功的制造出自径８ｍｍ，长８—１０ｍ的单晶Ａｌ线材．该技术的关键是用一个加热铸型和一个与之分离的冷却器代替传统连铸中的水冷结晶器使加热铸型内壁温度保持在熔点以上某一温度，避免型壁形核，同时在冷却器与铸型出口之间造成一个轴向温度梯度，形成定向凝固条件铸锭在离开铸型出口后的一小段距离内，表面仍呈液体状态，凝固后的铸锭表面光滑，呈镜面状态，故该技术属于一种Ｎｅａｒ－Ｎｅｔ－Ｓｈａｐｅ生产技术．由于凝固过程中固液界面呈向液态中凸出的形状，即铸锭中心先于表面凝固，可避免铸链中心缩孔缩松的产生，便于排除气体和夹杂，铸锭内部质量高，而且这种凸出的固液界面形状有利于晶体生长过程中的竞争生长，加速晶粒的淘汰过程，易于生产单晶线材单晶连铸棒材的抗拉强度比金属型多晶铸棒低约３８％，屈服强度持平，屈强比提高９３％，延伸率提高１１７％单晶试样拉伸断口收缩成针尖状．加工硬化程度很小，可以预言其塑性加工性能很高．由于组织致密，无铸造缺陷，气体和夹杂含量低，更重要的是无横向晶界，故导电率高测定结果表明单晶连铸铝棒材的电阻率为２６．４５５ｎΩｍ，而金属型铸棒表面细晶区和中心粗晶区的电阻率分别为２９．４９２和２８．?
The use of self-made small single crystal continuous casting equipment, successfully manufactured from diameter 8mm, length 8-10m single crystal Al wire. The key to this technique is to replace the traditional water-cooled crystallizer in a continuous casting with a heated mold and a separate cooler to maintain the inner temperature of the heated mold above a certain temperature above the melting point, to avoid wall nucleation, An axial temperature gradient is created between the mold and the exit of the mold to form a directional solidification condition. The ingot is still in a liquid state after leaving the exit of the mold. The surface of the ingot after solidification is smooth and mirror-like, Therefore, the technology belongs to a Near-Net-Shape production technology. As the solid-liquid interface in the solidification process is convex to the liquid shape, ie, the ingot center is solidified before the surface, shrinkage of the shrinkage cavity at the center of the casting chain can be avoided, the gas and inclusions can be easily eliminated, the ingot interior has high quality, This convex solid-liquid interface shape is conducive to the competitive growth of the crystal growth process, to speed up the grain out of the process, easy to produce single crystal wire single crystal continuous casting rod tensile strength lower than the metal polycrystalline casting rod 38%. The yield strength is flat, the yield ratio is increased by 93%, and the elongation is increased by 117%. The tensile fracture of the single crystal specimen shrinks into needle-like shape. The degree of work hardening is small, it can be predicted that its plastic processing performance is high. Due to its compact structure, no casting defects, low gas and inclusion content and, more importantly, no transverse grain boundaries, the high conductivity measurements show that the resistivity of single crystal continuous cast aluminum bars is 26.455 nΩm, The resistivity of the surface fine grain region and the center coarse grain region are respectively 29.492 and 28. ?