Solidification Of Sn-Pb Alloy Research Articles

Effect of permanent magnet stirring on solidification of Sn-Pb alloy

An experimental investigation has been conducted with respect to the influence of permanent magnet stirring (PMS) under different rotation speeds (ω=60, 120 and 150r/min) and center magnetic flux densities (B=757 and 1080Gs) on the solidification of Sn-20wt%Pb alloy. The magnetic field was generated by a pair of arc-shaped NdFeB permanent magnets with a gap that could be adjusted to obtain the required magnetic flux density. The effects of different values of ω and B were investigated by analyzing the driven flow intensity, surface and internal quality, macrostructure, microstructure and tensile properties. It was observed that with increasing ω and B there was significant improvement in the flow intensity of the liquid, surface pinholes, grain refinement and tensile properties. The results obtained have important implications for industrial metal casting processes.

Study on the Solidification of Sn-Pb Alloy under Direct Current Field by Synchrotron X-Ray Radiography

In this paper, synchrotron X-ray radiography was used to study the grain refining performance of direct current (DC) during the solidification of Sn-50 wt.% Pb alloy. Based on the radiographs, the variations of equiaxed grain number and dendrite growth rate with time were measured and analyzed. It is shown that DC mainly affects the microstructure formation through changing the nucleation behavior and the dendrite growth rate. When DC was applied during the whole process of solidification, the nucleation was enhanced and the dendrite growth was suppressed, which resulted in significant grain refinement.

Experimental Analysis of Seed Effect on the Directional Solidification of Sn-Pb Alloy

In this paper, an experiment model for the directional solidification of Lead/Tin alloy is built and the effects of different-shape seeds on the microstructures on the solidification microstructure are investigated. In a casting process, the temperature and concentration fields will affect the microstructures of materials and this influence is the key point of improving their mechanical and physical properties. It is not easy to control the morphology of solidifying microstructures. The scheme of directional solidification can make the microstructures grow along a fixed direction and it is also the base of single-crystal growth. In the experiment, a poly-grain seed with the same initial concentration of the solidifying casting is used to induce the columnar growth at the bottom portion of the casting, which could avoid the equiaxed growth due to the high undercooling or cooling rate there. In the experimental analysis, we studied the influences of different geometry seeds on the constrained growth, the preferential growth direction of dendrite, the grain size, the temperature gradient, the growth rate, the primary arm spacing and the secondary arm spacing. From the microstructure observation, the adding seed casting reduced the chill-affected and extended the directional solidification zone. This is expected to have the better or more complete structure of directional solidification. Keywords: Directional Solidification, Seed, Heat Transfer and Microstructure