Effect of Zinc Addition on the Microstructure, Thermal and Mechanical Properties of Indium-Tin-xZinc Alloys

摘要

The effect of different Zn content on the microstructure, thermal and mechanical properties of In-Sn-xZn alloys was investigated. The microstructure of the alloys was analyzed by optical microscopy, x-ray diffraction, transmission electron microscopy, scanning electron microscopy and energy dispersive spectroscopy. The results indicated that the alloys consisted of , and Zn phases. The phase was generated from the decomposed supersaturation phase in the peritectic structure, with less than 2.0wt.% Zn content, characterized by a 120 degrees C phase transition temperature. And a close mutual lattice relation was maintained between and phases. The alloys, with Zn content from 3.0wt.% to 6.0wt.% and a melting point at 108 degrees C, had an eutectic structure. Studies indicated that the morphology and distribution of the Zn phases were significantly affected by the phase. The primary Zn tended to grow along the vertical crystal orientations and to form a cube-shaped block in the phase. Other Zn existed in the form of a precipitate particle phase in the phase. Most of Zn was excluded from the phase region, which had an effect on the phase boundary of /. And the phase relationship between and in In-Sn-4Zn is [01121],(111)//(210). The performance of the material was significantly enhanced by Zn. When Zn content was 6.0wt.%, microhardness and elongation of the material were increased by about 160% and 100% respectively, compared with those of In-49Sn-1Zn. Under coupling of the melting interval and the hard phase, the wetting performance of the alloy decreased as the Zn content increased. And the increase of Zn content in the solder made the diffusion distance of Cu longer, which promoted the growth of intermetallic compound (IMC).