纳米铝熔化过程的分子动力学模拟

Molecular dynamics simulation of melting process on nano-aluminum

运用Compass力场的分子动力学方法,研究了含氧化层的纳米铝球颗粒熔点的变化规律。通过对铝球升温,探索了铝球粒径及氧化层厚度对其熔点的影响,以及含氧化层纳米铝球颗粒的熔化过程。铝粉粒径很小时,其表面形成的氧化层较薄,热膨胀作用使氧化层逐渐破裂。当粒径较大及氧化层较厚时,若温度升至氧化层熔点,由于铝球内核压力的协同作用导致氧化层突然破裂,铝原子与空气接触发生爆燃。结果表明:同一粒径的纳米铝粉,氧化层厚度越厚,氧化层熔化时爆裂现象越严重。

Molecular dynamics simulation with Compass force field was used to investigate the variation of the melting point of nano-aluminum wrapped by oxidized layer. By heating the nano-aluminum balls, the impact on melting points with different particle diameter of nano-aluminum balls and thickness of the oxidized layer, as well as melting process on nano-aluminum were explored. When the particle diameter was small, the thickness of the oxidized layer was thin; the hot expansion gradually made the oxidized layer to crack. As the particle diameter was large, the oxidized layer was thick and the temperature approached the melting point of oxidized layer, the pressure in in-core aluminum made the oxidized layer suddenly outburst. The released A1 atoms contacted with air and resulted in deflagration. It was indicated that for the same size of nano-aluminum particle, the thicker the oxidized layer was, the more severe the melting oxidized layer outburst was.