PHASE-EQUILIBRIA FOR THE ALUMINUM-RICH REGION OF THE AL-RU SYSTEM

Measurements by scanning electron microscopy, X-ray diffraction, and thermal analysis show that the aluminum-rich end of the published phase diagram for the Al-Ru system is incorrect. A new phase diagram is proposed for the aluminum-rich end of the diagram. The main differences from the previous diagram are as follows: (1) Al//1//3Ru//4 melts peritectically at 1403 degree C rather than at 1200 degree C, (ii) Al//6Ru melts peritectically at 723 degree C rather than congruently at 1340 degree C, and (iii) we find no evidence for the phase Al//1//2Ru, reported earlier. The kinetics of phase formation in this system are discussed with reference to the synthesis of metastable structures such as the icosahedral phase.