冲击加载过程中苯的液—固相转变

Solidification transformation of benzene under quasi-isentropic compression

利用一级轻气炮加载技术和最近发展的一种透光性测量技术,在线观测到液态苯在多次冲击压缩过程中透光性随时间变化特征.分析表明,导致透光性下降的原因是局部发生液—固相变而引起的光散射效应,且散射特征反映了相变过程的时间弛豫和空间积累特性.结果澄清了苯在冲击条件下液—固相变是否发生的争论,对冲击相变动力学研究提供了重要实验依据.

Kinetics of solidification of liquid benzene under high pressure has attracted much attention of scientists, and it is also one of long-standing disputes. In the present work, the gas-gun technique is combined with a recently developed measurement method of light transmittance, and the time dependence of light transmittance of liquid benzene is directly observed during successive multiply shock-compressions. The analysis shows that the transmittance decrease is caused by light scattering effects in a non-uniform optical medium, which is formed by local phase transformation of liquid-solid, and that the scattering feature reflects both the time relaxation and the spacial accumulation of transition process. The argument whether the liquid-solid phase transformation happens under multi-shock compression is clarified, and important experimental evidence is provided for the study of phase transformation Kinetics.