In situ diffraction study on decomposition of Ti2AlN at 1500-1800 degrees Celcius in vacuum

Authors

Wei Kong Pang, Curtin University of TechnologyFollow
It-Meng Low, Curtin University of Technology
Shane Kennedy, ANSTO
R I. Smith, Harwell Science And Innovation Campus

RIS ID

88680

Publication Details

Pang, W. K., Low, I. M., Kennedy, S. J. & Smith, R. I. (2010). In situ diffraction study on decomposition of Ti2AlN at 1500-1800 degrees Celcius in vacuum. Materials Science and Engineering A: Structural Materials: Properties, Microstructure and Processing, 528 (1), 137-142.

Abstract

The susceptibility of Ti2AlN to thermal dissociation at 1500–1800 degrees celcius 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 degrees celcius 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.