Self-ignition of amorphous alloys activated by exothermic crystallization

Increasing importance has been paid to ignition and combustion of metals for their wide engineering ap-plications. However, the ignition temperatures of pure metals are much higher than their melting points, leading to long ignition delays, agglomeration before ignition, slow burning rates and incomplete combus-tion. Here, we report on the ignition of amorphous alloys activated by exothermic crystallization, which is weakly dependent on oxygen. It is found that, though the crystallization enthalpy of an amorphous alloy is a constant value under different heating rates, its maximum available exothermic transition spe-cific power (Pmax T, trans, W/g) during crystallization is considerably enhanced by several orders of magnitude due to a high-rate heating. For example, Pmax T, trans of the Zr60Al15Ni25 amorphous alloy is magnified from 2.96 W/g at a heating rate of 1 K/s to-2.70 x10 4 W/g at a heating rate of 3.0 x 10 3 K/s. It is such a high Pmax T, trans that triggers a self-propagating exothermic solid-state reaction; as a result, a self-ignition is activated. Our finding sheds light on the ignition mechanism of amorphous alloys, which is scientifically important for their engineering applications as metalized energetic and reactive materials.(c) 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.