461832 High Density Reactive Composite Powders
density and strength. Tungsten components may be even more attractive in kinetic projectiles if their
rapid oxidation could be triggered by impact. However, igniting tungsten is difficult, probably because
of its high heat capacity and relatively high ignition temperature. This study is aimed to prepare and
characterize composite powders comprising tungsten, titanium, and boron. The targeted density of the
composite material was that of steel, 8050 kg/m3. Both boron and titanium have high heats of
combustion; more importantly, they are also capable of a highly exothermic intermetallic reaction
producing TiB and TiB2. This reaction is expected to be very rapid, and cause fast temperature increase
of composite particles, assisting ignition of tungsten. Further, it is expected that at high temperatures
all metals will proceed to oxidize producing thermodynamically favorable oxides as the final combustion
products. In this study, composite materials were prepared by mechanical milling. In order to achieve
fine mixing, tungsten was first balled milled with boron. Both metals are hard and produce a finely
mixed composite. This composite was then milled with titanium to produce the targeted ternary
compound. SEM imaging showed that the produced powder includes equiaxial fine particles with all
three components mixed on the submicron scale. Particle size distributions were measured using low-
angle laser light scattering. The mean particle size was 11.2 µm and the standard deviation was 1.7 µm.
Differential Thermal Analysis was performed for milled binary B·Ti composite as a reference, and for the
ternary W·B·Ti powders. Results showed an exothermic reaction between boron and titanium occurring
in the temperature range of 700-1400 K. XRD analyses of powders heated to 1400 K confirmed
formation of multiple new phases including all three elements. Powders were fed into a CO2 laser beam
and burned in air. Burn times of the particles and their combustion temperatures were measured.
Results will be presented and discussed in this talk.