Preparation and Structural Characterization of Rapidly Solidified Al-Cu Alloys

Rapidly solidified Al100-x—Cuxalloys(x = 5,10,1 5,25,35 wt%) were prepared and analyzed.High cooling rate increased the Cu solubility in 9.-AI matrix.The influence of the cooling rate on Cu solubility extension in Al was experimentally simulated.Thus the pouring was performed in metallic die and by melt spinning-low pressure(MSLP) technique.Melt processing by liquid quenching was performed using a self-designed melt spinning set-up which combined the cooling technology of a melt jet on the spinning disc with the principle of the mold feeding from low pressure casting technology.The thickness of the melt-spun ribbons was in the range of30—70 μm.The cooling rate provided by MS-LP was within 105—106K/s after the device calibration.The obtained alloys were characterized from structural,thermal and mechanical point of view.Optical microscopy and scanning electron microscopy were employed for the microstructural characterization which was followed by X-ray analysis.The thermal properties were evaluated by dilatometric and differential scanning calorimetric measurements.Vickers microhardness measurements were performed in the study.In the case of the hypereutectic alloy with 35 wt%Cu obtained by MS-LP method,the microhardness value increased by 45%compared to the same alloy obtained by gravity casting method.This was due to the extended solubility of the alloying element in the α-AI solid solution.