No abstract

Al-Si alloy at eutectic region as the research object, Electric pulse modification (EPM) were used to achieve simultaneous refinement and modification of eutectic silicon phase, in order to analyze the mechanism of electrical pulse modification to the alloy and analyzed how the EPM affects the solidification structure and the corresponding properties. We get the conclusion by observing the microstructure of the sample, measuring the hardness, calculating the volume fraction and the average size of primary silicon at different pulse frequency and voltage. By using this process the particle size of primary silicon was reduced from 50 µm to a range of 5-20µm and the shape changes from acicular to fine fiber when compared with the conventional casting process. Also, the result of mechanical test showed that the hardness increase from 105HV-156HV with the change in pulse voltage at 700V peak value it therefore increased with 49% and at 1000V decline to 144HV with increased by 37% with homogeneous distribution of eutectic silicon.

An online production technique was designed and automated for control system of the three-phase induction motor based on programmable logic controller (PLC) technology and a simplified system was used to carry out a material testing. The microstructure morphologies were observed by the optical microscopy and hardness test. The results have shown that electric pulse treatment significantly accelerated the recrystalliazation annealing of HSi65-1.5 alloy due to the short treating time, high heating rate and accelerated nucleation and lower final dislocation density and the optimum parameters where found to be annealing at 300°C, pulse voltage of 700V, pulse frequency of 15Hz and pulse time of 120s.