Kinetics of High Temperature Reaction in Ni-Al System: Influence of Mechanical Activation

Abstract

High temperature (>1000 K) reaction kinetics in the stoichiometric (1:1 by molar ratio) Al-Ni system was investigated by using the, so-called, electrothermal analysis (ETA) method. ETA is the only technique that allows studying kinetics of a heterogeneous gasless reaction at temperatures above the melting points of the precursors. Special attention was focused on methodological aspects of the ETA method. Two different reaction systems were studied: (i) initial Al/Ni clad particles; (ii) the same powders but after 15 min of high energy ball milling. Analysis of the obtained results leads to the conclusion that such mechanical treatment decreases the apparent activation energies of the reaction in the Ni-Al system, from 47 +/- 7 kcal/mol for the initial powder to 25 +/- 3 kcal/mol after ball milling. Comparison of these data with those reported previously was also made.

Combustion synthesis in nanostructured reactive systems

“…It is more important that these phases 339 possess high contact surface area and are devoid of oxygen [35]. 340 This leads to a significant decrease of reaction activation energy, 341 which was experimentally confirmed both by TGA/DTA and elec-342 tro-thermal explosion methods [40,41] and thus in some sense, a 343 mechanical activation process (MAP) of the reaction takes place. 344 However, one more microstructural aspect, which shows the for-345 mation of zones with the characteristic size of Ni and Al phases 346 in nanometer range is important (Fig.…”

Molecular dynamics simulations of the reaction mechanism in Ni/Al reactive intermetallics

“…These materials are fast burning [1] and reach high combustion temperatures [2] without significant volume expansion or the formation of gaseous products. Such characteristics make IRCs promising candidates for applications where strong, localized sources of heat are required.…”

Preparation and Reactivity of Gasless Nanostructured Energetic Materials

“…It was recently shown [6][7][8][9][10][11][12] that a number of gasless heterogeneous reactive systems (Ni+Al, Ti+C, Ti+B) that form intermetallic or refractory compounds could also be considered as energetic materials. The energy densities (kJ/cm 3 ) of those systems are closer or higher than that of TNT ( Table 1).…”