Papers by Author: Zhi Hu

Abstract: SiC nanoparticles reinforced AZ61 magnesium composites were fabricated by Ultrasonic method. The distribution of nanoparticles in the matrix and the fracture morphology of the composites were observed by SEM, and the mechanical properties of the composites were tested at room temperature. Experimental shows that SiC nanoparticles were dispersed well in the matrix with the pretreatment method. Compared with the matrix, the tensile strength and hardness of the composites were improved respectively. Meanwhile, the ductility of the composites didn’t be obviously decreased. The enhancement function of nano composites was predicted with the dislocation strengthening and Orowan dispersion strengthening mechanisms. The predicted results coincided well with experimental ones.

Abstract: The perfect semi-solid magnesium alloy had been prepared using ultrasonic stirring method. The effect of technological parameters such as melt temperature, ultrasonic power and ultrasonic treatment time on the microstructure of semi-solid AZ61 alloy had been investigated. The results showed that the better refined and well-distributed globular semi-solid magnesium alloy had been acquired with the increasing of output power of ultrasonic stirring when melt temperature and ultrasonic treatment time were at a certain range.

Abstract: The technology of computer numerical simulation on casting process is an important frontal field of material science and technology. The numerical simulations of camera shell in the pressure die casting process were carried out. The distributions of temperature and solidification time in the filling process were obtained. Based on the simulated results and the Niyama criterion G/ R , the positions of slack were predicted, which were agreement with the practical result. Consequently, an improved scheme was presented, in which the workpiece defects were obviously reduced. So it’s significant for the application of numerical simulation on improving the quality of the casting, shortening the period of producing, reducing the cost and guiding the engineer for taking reasonable method to optimize the technological design.