In Situ TEM Heating Study of the γ Lamellae Formation inside the α2 Matrix of a Ti-45Al-7.5Nb Alloy
In-situ heating transmission electron microscopy (TEM) was employed to investigate the initial stage of lamellae formation in a high Nb containing γ-TiAl based alloy. A Ti-45Al-7.5Nb alloy (at %), which was heat treated and quenched in a non-equilibrium state such that the matrix consists of ordered a2 grains, was annealed inside a TEM up to 750 °C. The in-situ TEM study reveals that g laths precipitate in the a2 matrix at ~ 750 °C possessing the classical Blackburn orientation relationship, i.e. (0001)a2 // (111)g and [11-20]a2 // <110]g. The microstructure of the in-situ TEM experiment is compared to results from ex-situ heating and subsequent TEM studies.
Sihai Jiao, Zhengyi Jiang and Jinglong Bu
L. M. Cha et al., "In Situ TEM Heating Study of the γ Lamellae Formation inside the α2 Matrix of a Ti-45Al-7.5Nb Alloy", Advanced Materials Research, Vols. 146-147, pp. 1365-1368, 2011