Formation of Whisker in Pure Sn under Tensile Stress and a Method of its Suppression

Effect of dislocation behavior on formation of whisker in pure Sn has been investigated. Slip system in β-Sn was determined; slip plane is , and Burgers vector b is . The magnitude of Burgers vector is larger than the smallest interatomic spacing in β-Sn. This means that there is broad space under the extra half plane of edge dislocation. It sould be noted that pipe diffusion along the edge dislocation is enhanced in β-Sn, resulting in easy supply of Sn atoms at the root of Sn whisker [1, 2]. Si-bearing particles, which precipitate on surface of bulk Sn by heat-treatment in quartz tube, suppress the accumulation of both edge and screw dislocations to same area. It is greatly effective for the suppression of the nucleation of Sn whisker.