Phase transformations and phase equilibria of a Ti-46.5Al-16.5Nb alloy. (5th July 2016)

• Record Type: Journal Article
• Authors: Xu, Shuai; Xu, Xiangjun; Xu, Yong; Liang, Yongfeng; Lin, Junpin
• Is Part Of: Materials & design. Volume 101(2016)
• Page Start: 88
• Page End: 94
• Publication Date: 2016-07-05
• Subjects: TiAl alloy -- Phase equilibrium -- CALPHAD -- Phase transformation -- Phase diagram; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2016.03.131
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: The isothermal sections of the phase diagram and the liquid projection of the Ti-Al-Nb ternary system as well as the phase transformations of a Ti-46.5Al-16.5Nb alloy were calculated using Pandat software. The solidification sequence and subsequent phase transformations of the alloy were verified by microstructural observations and thermo-analysis (TA). The tie-triangle of the three-phase region of α + β + γ at 1300 °C and the tie line of the α and β phases at 1400 °C were identified using electron probe microanalysis (EPMA). Neither the phase equilibria of the α, β and γ phases at 1300 °C nor the tie line of the α and β phases at 1400 °C are in agreement with the calculated phase diagrams reported in the literature. The solidification sequence and subsequent solid-state phase transformations of this alloy were determined as follows: liquid → liquid + β → β → α + β → α + β + γ → β + γ (The β phase and the B2 phase were not differentiated in the present paper.) The phase transformation temperatures were also measured by differential scanning calorimetry (DSC). Graphical abstract: Highlights: The tie-triangle of the α, β and γ phases at 1300 °C is validated. The tie line of the α and β phases at 1400 °C is validated. The constituted phases of the Ti-46.5Al-16.5Nb alloy are identified. The phase transformations of Ti-46.5Al-16.5Nb alloy are determined.