In situ diffraction study on decomposition of Ti2AlN at 1500–1800°C in vacuum

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The susceptibility of Ti2AlN to thermal dissociation at 1500–1800°C in high-vacuum has been studied using in situ neutron diffraction. Above 1500°C, Ti2AlN decomposed to TiNx primarily through the sublimation of aluminium (Al). The kinetics of isothermal phase decomposition at 1550°C was modelled using a modified Avrami equation. An Avrami exponent (n) of 0.338 was determined, indicative of the highly restricted out-diffusion of Al between the channels of Ti6N octahedra. The characteristics of thermal stability and phase transition in Ti2AlN are discussed. Characterisation of surface compositions and examination of cross-sectional microstructures of decomposed Ti2AlN, using synchrotron radiation diffraction and SEM, respectively, verify the findings of the neutron diffraction; that Ti2AlN decomposes to TiNx at the surface primarily via the sublimation of Al from grain boundaries. © 2010, Elsevier Ltd.
Neutron diffraction, Decomposition, Dissociation, Aluminium, Phase transformations, Scanning electron microscopy
Pang, W. K., Low, I. M., Kennedy, S. J., & Smith, R. I. (2010). In situ diffraction study on decomposition of Ti2AlN at 1500–1800°C in vacuum. Materials Science and Engineering: A - Structural Materials Properties Microstructure and Processing, 528(1), 137-142.