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Role of Pore Microstructures on the Decomposition Kinetics in MAX-Phase Composites

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Authors
Low, It Meng
Pang, W.
Date
2012
Type
Conference Paper

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Low, I.M. and Pang, W.K. 2012. Role of Pore Microstructures on the Decomposition Kinetics in MAX-Phase Composites, in M. Jaafar, A. R. Azura, K. H. Leong and A. Y. L. Leong (ed), 8th Asian-Australasian Conference on Composite Materials (ACCM-8), Nov 6-8 2012. Kuala Lumpur, Malaysia: AACM.
Source Title
Proceedings of the 8th Asian-Australasian Conference on Composite Materials
Source Conference
8th Asian-Australasian Conference on Composite Materials (ACCM-8)
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Abstract

In this paper, the role of pore microstructures on the susceptibility of MAX- phase composites to thermal dissociation at 1300-1800 °C in high vacuum has been studied using in-situ neutron diffraction. Positive activation energies were determined for the decomposition of MAX phases except for Ti3AlC2 where negative activation energy of 71.9 kJ mol-1 was obtained due to formation of fine pores on TiCx. An Avrami exponent (n) of < 1.0 was determined, indicative of the highly restricted diffusion of Al or Si between the channels of M6X octohedra. The pore microstructure of decomposed MAX phase has been shown to play a vital role in the kinetics of decomposition with coarse-pores facilitating the decomposition process but the fine-pores hindering it.