摘要
在透射电镜实验结果的基础上,提出了Bi-2212相向Bi-2223相转变的位错管扩散机制模型.根据固体扩散相变理论结合位错动力学公式,计算了在高温下Bi-2223相形核所需要的能量和生长速率.计算结果表明:(1)在850℃附近位错管扩散相变所需要的驱动力与室温下位错滑移所需要的驱动力在同一数量级,扩散速度可达到几十μm/s.(2)Bi-2223相形核所需要的能量远远大于其长大所需要的能量,这说明形核所需要的时间要比其长大所需要的时间长得多.
According to a vast amount of TEM observation results, a diffusion model through dislocation pipe for phase transformation from Bi- 2212 to Bi- 2223 has been proposed. Combining dislocation dynamics with diffusion theory, the nucleation energy and the growth rate of the Bi - 2223 phase have been calculated at the same time. The calculation results ： （ 1 ） Requisite force for the Bi - 2223 phase growth in the diffusion model at near 850℃ is roughly the same as that of the edge dislocation slip at room temperature. The growth rate may go beyond 10 μm per second. （2） The requisite energy of the nucleation for Bi - 2223 phase is much more than that of its growth. This suggested that requisite time of the nucleation during Bi -2212 to Bi -2223 phase conversion is longer.
出处
《材料与冶金学报》
CAS
2008年第4期293-298,共6页
Journal of Materials and Metallurgy
基金
美国能源部材料科学局
基础能源办公室资助课题
合同号DE-AC02-76CH00016
