Effects of Aging Temperature and Time on Crystallinity and CrystalGrowth of Sn/Sb Peritectic Alloy

Abstract

The effect of annealing conditions in terms of temperature and time on the structure growth of Sn- 5wt%Sb pritectic solder alloy has been investigated for thirteen samples. These samples were melted at 650°C, and treated at 50, 70,and 100°C for 2,4,6 and 8 hours. The microstructure observation before and after heat- treatment has been studied using X-ray diffraction and optical microscope techniques. The Results showed that, there are two major phases, β- Sn tetragonal solid- solution and SbSn hexagonal intermetallic compound phases. The parameters of microstructure in detailed were accurately determined. At higher aging time there is a little shifting toward a small angle of diffraction and the peaks became sharper. This means that at larger aging time, the d-spacing is greater than that at low aging time, especially for the lines (200),(101),(211),(112),(301) and (420). This may be attributed to the preferred orientation of the structure growth. Also, the particle size and micro-strain change with time for all temperatures examined. The changes in the particle size and grain boundaries were observed by increasing temperature and time. This is attributed to the recovery and crystalline growth processes with preferred
orientations. The reduction in dislocation density has been observed with increasing aging time and temperature. In the heat-treatment process, the changes in microstructure are strongly depending on the variations in dislocation density. As time increases, the more equilibrium phase-distribution is observed.