In order to reduce serious tendency of the shrinkage porosity in ZL205A alloy, the design of experiment technique, Taguchi method is introduced to optimize the process parameters of cylindrical shell ZL205A alloy parts produced by low-pressure die casting in this article. The effect of pouring temperature, filling time and packing pressure on the shrinkage porosity in ZL205A castings is investigated using the orthogonal array and Advanced Porosity Model in ProCAST to calculate the volume of shrinkage porosity. The effectiveness of selected casting parameters in reducing the shrinkage porosity in cylindrical shell ZL205A casting is verified through analysis of signal-to-noise ratio and analysis of variance. Numerical results indicate that the optimized process parameters, including a pouring temperature of 725 °C, filling time of 20 s and packing pressure of 175 kPa, can be used to reduce the formation of shrinkage porosity in ZL205A castings.

In this paper, the thermal diffusion behavior of Fe/Cu/Ni multilayer coatings was investigated by molecular dynamics. The results show that the Fe, Cu, and Ni elements can diffuse each other at 1250 K. Meanwhile, the intrinsic diffusion coefficients and interdiffusion coefficients of the Fe, Cu, and Ni were calculated. Besides, the diffusion mechanism for high melting-point elements of Fe and Ni at 1250 K was analyzed in the paper. According to the simulation result, the Fe and Ni lattices were disturbed by the active Cu particles. Fe and Ni particles at higher energies may move out of their original positions and migrate into the Cu lattice randomly. Thus, the Fe and Ni elements were involved in the thermal diffusion. This can be confirmed by the decrease of the peak and the disappearance of the secondary peak in the radial distribution function curves. However, the position of the curve peaks did not change. Thus, the lattice structure was still maintained during the whole diffusion process. The thermal diffusion of the three elements was carried out by particle substitution at the lattice positions. It was a solid phase diffusion process. Furthermore, there was a clear particle diffusion asymmetry at the original interface of the element. It was consistent with the diffusion asymmetry of diffusion-couple experiments. The primary reason for this diffusion asymmetry was the difference in the interaction potential of the three elements. This asymmetry was ultimately reflected in the intrinsic diffusion coefficient and the interdiffusion coefficient of each element. For the Fe–Cu–Ni ternary system, the largest diffusion coefficient was copper and the smallest was iron at 1250 K.