Eur. Phys. J. B (2016) 89: 280
https://doi.org/10.1140/epjb/e2016-70326-9

Regular Article

Investigating the effects of phosphorus in a binary-phase TiAl-Ti₃Al alloy by first-principles: from site preference, interfacial energetics to mechanical properties

¹ Department of Physics, Beihang University, Beijing 100191, P.R. China
² Beijing Key Laboratory of Advanced Nuclear Materials and Physics, Beihang University, Beijing 100191, P.R. China
³ Beijing Institute of Control and Electronic Technology, Beijing 100038, P.R. China

^a e-mail: hbzhou@buaa.edu.cn

Received: 24 May 2016
Received in final form: 2 November 2016
Published online: 21 December 2016

Abstract

We investigate the site preference of phosphorus (P) and its effects on the mechanical properties of the binary phase TiAl-Ti₃Al alloy using a first-principles method in combination with empirical criterions. We show that P is energetically sitting at the substitutional Al site in the Ti₃Al layer of the TiAl/Ti₃Al interface, which can be understood from the difference of electronegativity between P and Ti/Al. Both the cleavage energy (γ_cl) and the unstable stacking fault energy (γ_us) decrease with the presence of P, which indicates the strength of the TiAl/Ti₃Al interface will be weaker and the mobility of the dislocation will be easier induced by P. Further, we demonstrate that the ratio of γ_cl/γ_us of TiAl/Ti₃Al interface with P is 5.03, 0.19% lower than that of the clean TiAl/Ti₃Al interface, suggesting that the P impurity will slightly reduce the ductility of the TiAl/Ti₃Al interface.