Influence of permanent magnet stirring on dendrite morphological and elastic properties of a novel Sn–Ag–Cu–Sb–Al solder alloy by ultrasonic pulse echo method

Abstract

Preventing columnar β-Sn grains forming during manufacture have undoubtedly become major challenges. Columnar grains are commonly considered as unfavorable as their existence can relocate defects of solidification and deterioration in mechanical properties; however, the practical application of permanent magnetic stirring (PMS) during manufacture assuredly makes columnar grains easy to avert. In this published work, we studied the influence of PMS application on the solidification microstructures (growth morphology), elastic properties using pulse echo overlap (PEO) method, electrical resistivity and tensile properties of SAC(0505)–Sb–Al solder alloy. The direct result shows that the equiaxed β-Sn grains produced with applying PMS instead of higher aspect ratio columnar β-Sn grains was expected due to the induced Lorentz force. Hence, both the elastic modulus and hardness are typically decreased as the ratio of Poisson increased with applying PMS. In addition, the Pugh ratio has elucidated the ductility behavioral of the alloy sample. The tensile testing results exhibited possible enhancement in ductility by PMS, which could tremendously increase the elastic compliance of bulk solders. The electrical resistivity displays increase in the ionic contribution with PMS. These remarkable results offer innovative methods for predicting the final microstructure to properly control dendritic growth in metallic alloys.