Critical evaluation of the Aluminium–Tantalum–Titanium system

Experimental study and thermodynamic re-assessment of the binary Al–Ta system

“…The phase close to equiatomic TaAl (in the present work designated as 4) was reported in [14,17,19,34]. Although Subramanian et al [14] claimed the peritectic reaction L p þ s 4 4 to take place at 2043 K, this phase never was found in as-cast alloys [17].…”

“…The width of the Ta 48 Al 38 -phase (4) at 1733 K was identified to range from 50.7 to 56.6 at.% Ta. This phase was originally named b in [24] but to avoid confusion in the ternary Al-Ta-Ti system, where b usually denotes the (b-Ti,Ta) solution phase (see [34]) it is designated here as 4. The s-phase was unambiguously identified in the Ta-rich side for a wide concentration range including the ideal composition Ta 2 Al [6,7,14,19,20,24,29,31,32,44,47].…”

“…1) was based on CALPHAD modeling of available phase equilibria data (mainly [19,20,32]) and thermodynamic properties [35]. It was used in later works for ternary systems [33,34] and in Landolt-Bö rnstein encyclopaedic issues [36,37]. An overview of literature data on phase structure and equilibria is presented below.…”

Experimental study and thermodynamic modelling of the ternary Al–Ta–Ti system

“…It was observed both in bulk alloys annealed at 1373 K and also in some of the diffusion couples [10]. However, it was not taken into account in the assessments [11,13,15]. Recently, the ternary compound close to the stoichiometric composition Ti 4 TaAl 3 has been observed by Lapin et al [27] in Tie46Ale8Ta (at.%) after long-time aging at 1023 K. As it was established by XRD, the crystal structure of this phase corresponds to B8 2 [27] and is identical to the s-phase of the AleNbeTi system [12].…”

“…The authors of Refs. [11,13] provide a critical evaluation of experimental data on phase relationships in the AleTaeTi system and a recommended set of internally consistent phase diagrams, accepting the constituent binary AleTa, AleTi and TaeTi phase diagrams from Refs. [16,6,8], respectively.…”