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Self‐Propagating High‐Temperature Synthesis of Ti 3 SiC 2 : II. Kinetics of Ultra‐High‐Speed Reactions from In Situ Neutron Diffraction
Author(s) -
Riley Daniel P.,
Kisi Erich H.,
Hansen Thomas C.
Publication year - 2008
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2008.02637.x
Subject(s) - nucleation , neutron diffraction , materials science , activation energy , kinetic energy , phase (matter) , kinetics , avrami equation , stoichiometry , diffraction , thermodynamics , analytical chemistry (journal) , crystallography , chemistry , crystal structure , physics , crystallization of polymers , organic chemistry , chromatography , quantum mechanics , optics
In situ neutron diffraction data at 0.9‐s time resolution during the self‐propagating high‐temperature synthesis of Ti 3 SiC 2 from stoichiometric 3Ti+SiC+C mixtures have been further analyzed to give the phase quantities during all five stages of the identified reaction [(i) preheating, (ii) α→β phase transformation in Ti, (iii) preignition reactions, (iv) intermediate phase formation, and (v) rapid nucleation and growth of Ti 3 SiC 2 ]. The phase quantities thus determined have been used, in conjunction with temperatures estimated from lattice parameters and thermal expansion data, to determine the kinetic parameters for the nucleation and growth stage using a nonisothermal form of the Avrami kinetic equation. The analysis gave an Avrami exponent, n , close to 3 in agreement with nucleation and the observed two‐dimensional growth of Ti 3 SiC 2 crystals. An activation energy of ∼45 kJ/mol was also estimated.