EN
The peak counting rate, F(T), for Bi_{40}Sn_{60} alloy in the temperature range from room temperature to 400°C was measured in three consecutive heating-cooling runs. Significant changes in F(T) were observed in the temperature interval between the solidus and liquidus temperature. The magnitude of these anomalies systematically diminishes in consecutive heating-cooling runs. Noticeable changes of values of F(T) parameter in the liquid alloy were observed, too. These effects were connected with trapping of positrons at the grain boundaries-defects and in the short-range ordered regions in the liquid alloy. Also microscopic structure of sample before and after measurements cycles was observed.