MECHANICAL ALLOYING IN THE AL-BI ALLOY SYSTEM

Mechanical alloying (MA) was carried out to investigate the MA behavio ur of the immiscible Al-10, 30 at % Bi alloys. After the MA processing , the Al and Bi were finely and homogeneously alloyed. The Bi crystall ite size decreased to 25 nm and 30 nm in the Al-10 at % Bi and Al-30 a t % Bi alloys, respectively. By increasing the MA time, the hardness i ncreased up to a value of 80 H-v, which is larger than that obtained f rom the rule of mixtures. The lattice parameter of Bi decreased by abo ut 0.27%, which shows the formation of a non-equilibrium hcp Bi super- saturated solid solution. The extended solubility of Al in Bi was 1.9% in the Al-30 at % Bi alloy. Due to the extended solubility, depressio n of the melting temperature of hcp Bi was confirmed in the mechanical ly alloyed Al-Bi alloys. The maximum depression in the temperature was about 10 K. The measured values corresponded well with those estimate d from the extrapolation of the solidus line.