Seite - 183 - in Advanced Chemical Kinetics

systemusing electrothermography. Their results showed that the reactions occur first through grain boundarydiffusion, followedbydiffusion of the solidmetal into the liquidphase [109]. Finally,Mukasyan et al. examined theNi/Al systemusing a combination of TRXRDandETE, showing that the reaction mechanism itself changes based on the structure, this work is highlighted inanabovesection[116]. Thuswemay conclude that althoughawidevariety of studieswere conducted on theNi/Al systemwith many different experimental and structural conditions, the reported values of activation energies vary drastically. Additionally, therewould be great benefit to combining utilizing multiple methods simultaneously to bridge understanding between the different experimental techniques. 11.Futuredirections inSHSkinetics More complete understanding on the kinetics of SHS reactions is vital for both fundamental scienceandalso forpracticalor industrial reasons.Tobetterunderstandthekinetics, combina- tionsof techniquesmustbeutilized, specifically coupling techniques thatgive informationon thekineticswhile simultaneously examining thephase transformations that areoccurring. To further understand the reaction mechanisms, additional studies must be conducted on the relationshipbetweenthestructureandtheresultingkinetics.Additionally,workmustbedone to compare the different methods of studying kinetics and their interrelationships. In the limited caseswhere there is data available for the same system across different techniques, Figure10. Arrheniusplots for reactions inAlcladbyNisystemsbeforeandafterhighenergyballmilling.Adaptedfrom Shteinbergetal. [12]. Kinetics of Heterogeneous Self-Propagating High-Temperature Reactions http://dx.doi.org/10.5772/intechopen.70560 183