Reaction Scheme and Liquidus Surface of the Ternary System Aluminum-Chromium-Titanium

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 40; no. 12; pp. 2980 - 2986
• Main Authors: Chen, Hailin, Weitzer, Franz, Krendelsberger, Nataliya, Du, Yong, Schuster, Julius C.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.12.2009; Springer; Springer Nature B.V
• Subjects: Alloys; Applied sciences; Binary system; Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystal structure; Exact sciences and technology; Materials Science; Metallic Materials; Metallurgy; Metals. Metallurgy; Nanotechnology; Solid solutions; Structural Materials; Surfaces and Interfaces; Thin Films; Peritectic Reaction; Solid Solution Phase; TiAl3; Isothermal Section; Differential Thermal Analysis; Chromium; Ternary system
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-009-0014-z

The constitution of the ternary system Al-Cr-Ti is investigated over the entire composition range using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), differential thermal analysis (DTA) up to 1500 °C, and metallography. Solid-state phase equilibria at 900 °C are determined for alloys containing ≤75 at. pct aluminum and at 600 °C for alloys containing >75 at. pct Al. A reaction scheme linking these solid-state equilibria with the liquidus surface is presented. The liquidus surface for ≤50 at. pct aluminum is dominated by the primary crystallization field of bcc β (Ti,Cr,Al). In the region >50 at. pct Al, the ternary L1 2 -type phase τ forms in a peritectic reaction p max at 1393 °C from L  + TiAl. Furthermore, with the addition of chromium, the binary peritectic L  +  α (Ti,Al) = TiAl changes into an eutectic L  =  α (Ti,Al) + TiAl. This eutectic trough descends monotonously through a series of transition reactions and ternary peritectics to end in the binary eutectic L  = Cr 7 Al 45  + (Al).