Liquid gallium penetration along grain boundaries in pure Al and Al-based alloys.

The kinetics of liquid Ga penetration along grain boundaries in pure At, Al-Mn (50 ppm Mn) and Al-Ga alloys (with concentration 0.7, 1 and 3% mass. Ga) was studied. It was shown that crack-like channels filled by liquid Ga were formed along all grain boundaries. Their width was about 1-3 mu m. Investigation of quenched state showed that in all samples, channels had grown with linear kinetics, and that the propagation rate depended on impurity concentration in alloys: 35 mu m/s for Al-Mn alloy, 14 mu m/s for pure At and 9 1 mu m/s for At with (0.7-3) % Ga alloys. The difference in penetration rates of pure At and At based alloys are discussed in terms of internal stress and mechanical properties.