Phase equilibria of the Mo–Al–Ho ternary system

Abstract

Investigation into the reactions and phase equilibria of transition metal elements (i. e. Mo, Zr, Cr, V and Ti), Al and rare earths is academically and industrially important for the development of both refractory alloys and lightweight high-temperature materials. In this work, the equilibria of the Mo–Al–Ho ternary system at 773 K have been determined by using X-ray powder diffraction and scanning electron microscopy equipped with energy dispersive X-ray analysis. A new ternary phase Al4Mo2Ho has been found and the other ternary phase Al43Mo4Ho6 is observed. Ten binary phases in the Al–Mo and Al–Ho systems, including Al17Mo4 rather than Al4Mo, have been determined to exist at 773 K. The homogeneity ranges of AlMo3 and Al8Mo3 phase are 7.5 at.% and 1 at.%, respectively. According to the phase-disappearing method, the maximum solubility of Al in Mo is about 16 at.%.