Study On Iron-Aluminum Bimetal Casting Technology And Their Interface

On account of the combination of different materials’advantages, composite materials have been playing a more and more important role in nearly every area in this world. Therefore, the investigation of composites is attracting an increasing amount of experts and scholars. Among the various kinds of conposites, bimetal casting composites has a bright future for its simple process and low cost. However, with such a short contact time and a high cooling rate during the casting process, it usually does not has a good interface, which has been the bottleneck in the production and application of casting composites. So how to improve the interface quality and other properties is the concentration of our investigation.In order to get aluminum-iron composite wire through casting and reduce the cost of ACSR/AC(aluminum conductor aluminum clad steel reinforced), the process of aluminum-iron compound casting is proposed. In this experiment, the solid iron wire was dipped into liquid aluminum for some time and then aluminum metallic of800℃was cast around it through the casting mould specially designed. A cohesion area about10μm-30μm composed by aluminum and iron was achieved after this process in which the aluminum content can be up to66.67percent. Meanwhile, the microhardness is over HV250. The cohesion area is mainly composed of Fe2Al5and FeAl according to thermodynamic data. In contrast, without the hot dipping treatment, a10μm wide gap between the two metals was observed under SEM and verified by results of energy spectrum analysis and microhardness test. The results suggest that a metallurgical interface was achieved between aluminum and iron via casting, which contribute to the investigation of producing aluminum-iron composite wire by the method of casting.To increase the diffusion level between iron and aluminum and to improve the interface quality of bimetal cast, we did more research. Commonly used alloy elements like Ni, Cr and Zr was added to the hot dipping melt respectively with a mass fraction of1%-2%. And all the other experimental parameters keep the same. The results of morphological observation, component analysis and properties tset showed that the alloy elements do boost the diffusion ability of both iron and aluminum, so the width of the interface increased greatly to200-400μm, which is also made up of FeAl, Fe2Al5and FeAl3. Moreover, iron-aluminum intermetallic was found in the aluminum area. While with the existence of Cr, dispersion distribution of globular new phase separating out, which is of great benefit to the matrix..To solve the problem that aluminum alloys used for automobile engine cylinder do not have a high strength and high wear resistance, our work focused on the HT250-ZL101A bimetal casting technology. In this experiment, the solid HT250was dipped into liquid aluminum alloy ZL101Afor5min, lOmin,15min,20min separately and then ZL101A metallic of750℃was cast around it through the casting mould specially designed. From the results we can learn that along with the growth of the time, transition zone begin to form and widen.After casting all the samples mentioned abo.ve were undertaken the same heat treatment technology. That is to be in500℃for4hours and in200℃for6hours. All the Fe-Al bimetal cast’s transition zone become wider, especially the one whose hot dipping melt containing Cr. Its transition become much more smooth and its width can be hundreds of micrometers.