Electrical resistivity and positron lifetime studies of precipitation effects in Al-Cu-based alloys

The improved workability of the commercial automatic machine designed alloy Al-Cu-Bi-Pb is guaranteed by the presence of Pb. Nevertheless, the toxic e lement Pb reduces some of the alloy properties. Therefore new Pb-free machi nable Al-based alloys are developed. The Al-Cu-Bi-Sn alloy belongs to these non-traditional materials. The contribution deals with the investigation o f precipitation effects in Al-Cu-Bi-Sn alloy during step-by-step isochronal annealing up to 500 degrees C after previous solution heat treatment by me ans of positron annihilation spectroscopy completed with electrical resisti vity measurements and results of independent transmission electron microsco py studies. The used combination of experimental methods gives the possibil ity to detect separately the redistribution of Sn and Cu atoms in the matri x and to study the influence of vacancies on this process.