Powder Metallurgical TiAlNb Alloy with Modulated γ/α2/B19 Microstructure

In TiAl alloys with additions of beta stabilizers (Nb, Mo, V) the formation of an orthorhombic B19 phase has been observed by high-energy x-ray diffraction and transmission electron microscopy. According to previous studies the incorporation of the B19 phase into a modulated microstructure results in a good combination of strength and ductilty which motivates further studies of this phase.

The B19 phase is closely related to the hexagonal (Ti3Al) alpha2 phase and to the tetragonal (TiAl) gamma phase.  Synchrotron measurements during in-situ heating illustrate that B19 forms by small atomic displacements in the basal plane of the parent alpha2 phase and allow to monitor the stability of the B19 phase with time and temperature.

In an effort to develop a PM TiAl alloy with a modulated B19 containing microstructre we explore the effect of alloying and heat treatments onto the microstructure of Ti 45Al 5Nb alloys.