Markus Eumann

Re-evaluation of phase equilibria in the Al - Mo system

Abstract Phase equilibria and homogeneity ranges of the intermetallic phases in the Al–Mo system have been determined. The microstructures of samples of fixed composition and of diffusion couples were investigated by light-optical and scanning electron microscopy, the crystallographic structures and lattice constants were established by X-ray diffraction and the compositions of the phases were determined by electron probe microanalysis. In addition, transition temperatures were determined by differential thermal analysis. The homogeneity ranges of the Al-rich intermetallic phases are narrow, with about 0.1 to 0.4at.% widths. The phases and phase equilibria as established in previous studies have been confirmed with the exception of the phase Al3+xMo1–x, which has not been detected. The congruent melting point of Al8Mo3 was found at 1546±3°C and the Al-rich phase boundary for AlMo3 has been determined between 800 and 1200°C.