Effect of microstructure control on the reaction characteristics in Al/Ni reactive
powder
Sang-Hyun Jung
1
*, Kibong Lee
1
1
The 4
th
Research and Development Institute-2
nd
Directorate, Agency for Defense
Development, Daejeon, 34060, Korea
Abstract
A microstructure and reaction characteristics that appear in Al/Ni reactive
materials and the correlation between those were investigated. 3 types of Al/Ni
reactive material powders, that are clearly distinguishable in terms of
microstructure, were prepared by using 3 kinds of mixing processes (i.e. turbula
mixing, attrition milling, and planetary milling). The Al/Ni powder prepared by
using turbula mixer shows that the shape was maintained from initial state of raw
Al and Ni powder. In contrast, the Al/Ni powder prepared by using attrition mill
shows that the shape was distorted and grain size largely decreased from the raw
materials. And the powder prepared by using planetary mill was completely deformed
from the initial state of raw materials and represents a new type of
microstructure (i.e. nano-lamella structure). To compare the reaction initiation
temperatures of these powders, differential scanning calorimetric analysis was
performed. As a result, the initiation temperature varied more than 200
o
C
according to the changes in microstructure. In order to compare reaction rate, 3
types of compacts which is consolidated from the different powders were also
observed for their reaction characteristics by high speed camera at a condition of
10,000 fps (frame per seconds). And it was found that the reaction rates also
varies greatly depending on the microstructure of the powders. These results
suggest that reaction characteristics of reactive materials can be controlled by
tailoring their microstructure.
Keywords: reactive materials, mechanical alloying, nano-lamella, Al-Ni reactive
powder, self- propagating reaction
*Corresponding author: Sang-Hyun Jung (sanghyun@add.re.kr
); Tel: +82-42-821-4282;
Fax: +82-42-823-3400-16265
1. Introduction
Recently, the studies have been attracting attention to use Reactive Materials
(RM) and Reactive Material Structures (RMS) for military purposes [1]. RM are
usually classified into two categories. One is an intermetallic system in which an
intermetallic reaction occurs between a metal and a metal such as Al-Ni [2], Al-Zr
[3], and Al-Ti [4] and the other is a thermite system in which a thermite reaction
occurs between a metal and a metal oxide such as Al-CuO [5], Al-MoO3 [6], and Al-
Fe2O3 [7]. The RMS are usually prepared by structuralizing RM of a powder state.
For structuralizing, cold isostatic pressing and cold spray techniques are
generally used.
RMS are also called as HDEM (High Density Energetic Materials) in a sense that
