STUDY OF THE STRUCTURE AND PROPERTIES OF LEAD-FREE RAPIDLY SOLIDIFIED ZINC-BASED ALLOYS DURING A HEAT TREATMENT

Abstract

The results of studies of the effect of ultrahigh melt cooling rates, equal to at least 10^5 K/s, on the properties of rapidly solidified alloys of the Zn-Sn system are presented. The upper region of the foil, in contact with the crystallizer during solidification, had more dispersed particles of the second phase, and as the distance from the upper layers increased, the particle sizes increased. At room temperature, the decomposition of a supersaturated solid solution proceeds with the release of dispersed particles. Additional heat treatment leads to the coarsening of the particles of the second phase, and helps to reduce the microhardness. Rapidly solidified foils with a maximum zinc concentration are characterized by the presence of a (0001) texture, which weakens as the tin content in zinc increases, and upon alloying up to 30 wt. % Sn is rearranged to (10 10) texture. Heat treatment up to 160 °C does not change the texture.

Keywords

• rapidly solidification
• lead-free solders
• zn-sn alloy
• microhardness
• unit cell
• isochronous annealing
• decomposition
• solid solution