γ-TiAl基双相合金片层组织不连续粗化的驱动力与动力学

Driving Force for Discontinuous Coarsening of the Primary Lamellar Structure in Twophase γTiAl Based Alloys

应用金相显微镜、扫描电镜测定了Ｔｉ４５ａｔ％Ａｌ合金的初生片层组织发生不连续粗化时的转变速度及片间距。利用亚正规溶体模型计算了不连续粗化时的自由能变化。结果表明，不连续粗化的转变驱动力主要来自化学自由能项；不连续沉淀模型对描述初生片层的不连续粗化仍是有效的，但此时粗化片层前沿界面的互扩散系数将大为降低，接近体扩散系数。

During the discontinuous coarsening (DC) of the primary lamellar structure (PLMS) in the Ti45at% Al alloy, growth rate and space distance of DC were measured by optical microscopy and SEM The change of free energy is calculated by the subregular solution model The results show that the driving force for DC is provided mostly by the chemical free energy The model of discontinuous precipitation is still useful to describe the DC of PLMS, in which case the interdiffusion coefficient at the frontal interface is considerabrably decreases, and approaches to the lattice diffusion coefficient