Phase equilibria and multi-element interaction study in the metal-rich side of the Nb–Ti–Si–Al quaternary system. (May 2020)

• Record Type: Journal Article
• Authors: Sun, Zhiping; Wu, Wenqing; Tian, Xiaodong; Zhang, Fengying; Ai, Cheng; Zhang, Xuemin; Li, Yuqin; Guo, Xiping
• Is Part Of: Intermetallics. Volume 120(2020:May)
• Publication Date: 2020-05
• Subjects: Phase equilibria -- Thermodynamic -- Alloying -- Multi-element interaction -- Microstructure -- Nb–Ti–Si–Al; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2020.106760
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: The knowledge of phase diagram is theoretical principle for compositional design. Since Ti and Al are important alloying elements for Nb–Si alloys, and Nb and Si are important alloying elements for Ti–Al alloys, Nb–Ti–Si–Al phase equilibria is prerequisite for optimal microstructural design of both Nb–Si and Ti–Al systems. In this work, key alloys were selected firstly according to calculated isothermal section based on extrapolated thermodynamic description, then key alloy ingots were prepared by arc-melting and heat treated to reach equilibrium state. Currently obtained phase equilibria data coupled with critically reviewed literature data were employed to study the element interaction of relative phases (α-Nb5 Si3, β-Nb5 Si3, Ti5 Si3, Nb3 Al and TiAl et al.) in the Nb–Ti–Si–Al system. Thermodynamic parameters of these phases were modified accordingly to reproduce the determined phase relationships. Finally, the important phase equilibria features of the Nb–Ti–Si–Al system were described with several isothermal sections. The phase equilibria extending from ternary systems and new phase equilibria appearing in the quaternary space were demonstrated in this work. Highlights: Main two phase equilibria in metal-rich side of Nb-Ti-Si-Al quaternary were Bcc+α-Nb5 Si3, Bcc+(Nb, Ti)3 Si and Bcc+Ti5 Si3 . Main three phase equilibria in metal-rich side were Bcc+α-Nb5 Si3 +(Nb, Ti)3 Si, Bcc+α-Nb5 Si3 +Ti5 Si3 and Bcc+α-Nb5 Si3 +Nb3 Al. Main four phase equilibria in metal-rich side were Bcc+α-Nb5 Si3 +Ti5 Si3 +Nb3 Al and Bcc+α-Nb5 Si3 +Ti5 Si3 +(Nb, Ti)3 Si.