GRAIN-BOUNDARY WETTING BY SECOND SOLID PHASE IN Zn-Al POLYCRYSTALS AND BY Al-BASED SOLUTION IN Zn BICRYSTALS

摘要

The microstructure of Zn-5 wt.% Al polycrystals was investigated in the temperature range from 250 to 375°C. The structure of interlayers of the Al phase at individual grain boundaries in Zn bicrystals was also studied. It was shown experimentally that, depending on the annealing temperature and the grain-boundary energy, the second (Al) solid phase forms either a chain of individual lens-shaped inclusions or continuous homogeneous interlayers at grain boundaries in Zn. Therefore, a phase transition with grain-boundary wetting by the solid phase occurs in the Zn-Al alloy. Thermo dynamically, this transition is similar to the phase transition with grain-boundary wetting by a liquid phase. A tie line of the phase transition with grain-boundary wetting by the solid phase is plotted in the conventional bulk Zn-Al phase diagram.