High-temperature phase equilibria with the bcc-type β (AlMo) phase in the binary Al–Mo system. (April 2017)

• Record Type: Journal Article
• Authors: Kriegel, Mario J.; Walnsch, Alexander; Fabrichnaya, Olga; Pavlyuchkov, Dmytro; Klemm, Volker; Freudenberger, Jens; Rafaja, David; Leineweber, Andreas
• Is Part Of: Intermetallics. Volume 83(2017:Apr.)
• Page Start: 29
• Page End: 37
• Publication Date: 2017-04
• Subjects: Intermetallics (aluminides) -- Thermodynamic properties -- Phase stability -- Thermal stability -- Differential thermal analysis -- Electron microscopy, transmission; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2016.12.004
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: The binary system Al–Mo is a key system for the development of refractory aluminides. This development involves the thermodynamic modeling of multicomponent materials systems such as TiAl- and NiAl-based systems. Due to inconsistencies within the literature data, the phase equilibria with the high-temperature β (AlMo) phase were re-investigated with alloys in the as-solidified state and after heat-treatment at 1773 K using complementary experimental methods such as metallography, electron-probe microanalysis (EMPA), X-ray diffraction (XRD) and thermal analysis. The obtained results show the congruent formation of β at nearly equiatomic composition and a good agreement with the phase equilibria at 1773 K, which were determined in an earlier work. In addition, the structural disorder in this high-temperature phase was confirmed by means of XRD and transmission electron microscopy (TEM) measurements. The diffuse scattering observed in the electron diffraction patterns taken at quenched β (bcc) alloys indicate a soft phonon mode behavior of this phase, which differs substantially from the vibrational characteristics of the bcc Mo-rich solid solution. Graphical abstract: Highlights: The β (AlMo) phase forms congruently upon solidification. Diffraction methods confirmed the disordered nature of the high-temperature β phase. Diffuse scattering indicates a soft phonon mode behavior of quenched bcc β alloys.