In Situ Synchrotron Study of B19 Phase Formation in an Intermetallic γ-TiAl Alloy

Abstract

A multitude of phases exists in the binary Ti–Al phase diagram and even greater numbers are formed in structural TiAl alloys, which contain additional alloying elements to improve their properties. In the current study, a Ti–45 Al–3 Mo–0.1 B (in at%) alloy was investigated with respect to the phases occurring in chemical non-equilibrium. In situ high-energy X-ray diffraction experiments enabled to identify a transient phase to be of the B19 type and to determine its temperatures of formation and dissolution.

In situ high-energy X-ray diffraction experiments were conducted on a heat-treated and quenched Ti–45 Al–3 Mo alloy. As shown in the image, B19 phase was formed as a transitional phase during the α₂ → γ phase transformation upon heating. In this work, the temperatures of B19 formation and dissolution are given and the structural similarities which facilitate the transformation via a transitional phase are elaborated.