Influence Of RE On The Structure And Performance Of Directionally Solidified Al-4.5% Cu Alloy

With the development of society, people's wishes that materials have more excellent performance becomes more urgent, thus the method used more and more extensive by obtaining the ideal structure method through the preparation course of controlling the material . Controlling the course of solidifying already becomes an important way to improve the traditional material's performance and discover new materials. Directional solidification technology is a technical course that use certain equipment to make directional structure material with excellent performance at determinate conditions.In my paper I did directional solidification experiment with Al-4.5%Cu alloy under the 5kg crucible directional solidification stove. With the same temperature grads and draw velocity, Make a series of samples which have directional solidification structure with different kind and different RE qulity. Then we incised the sample to a little bit and analysed under the optical microscope and SEM.The result shows: The directional solidification structure has obvious orientation and the structures grow along with the draw direct. With determinate temperature grads, different RE percent have different structure. The structure changed with the change of the draw velocity; When the draw velocity is small, the solidification structure is bulky cystiform; When the draw velocity is large, the structure is obvious dendrite; And with the growth velocity added gradually, the dendrite structure minished rapidly-, At the same time when the growth velocity continue to add and exceed to a critical number ,we can obtain the obvious fine cystiform structure.When we put in 0.31% La, its primary dendrite spacing obtained the minimum 410.4395μm at the same series. When we put in 0.29% Ce, its primary dendrite spacing obtained the minimum 440.9562μm at the same series. When we put in 0.39% multiple RE, its primary dendrite spacing obtained the minimum 384.5887μm at the same series and this is the minimum of all sample which has fine structure and excellent performance.