The Role of Interfacial Structure in the Evolution of Precipitate Morphology

本研究通过岩壁机制的概念探讨了沉淀的成核和生长。用热段透射电镜测定了镍铬合金中面心立方/体心立方相界面边界上生长边缘的形成速度。将经典成核理论预测的岩壁形成速率与实验测量的岩壁形成速率进行了比较。评价了溶质过饱和度、应变能和相间边界能对岩壁成核的贡献。确定了生长过程中相间析出相/基体边界处错配位错的作用。这些结果应该在用不变线模型解释析出相形状的几何方法和析出相生长的物理机制之间提供联系。

This investigation explores nucleation and growth of precipitates through the concept of ledge mechanisms. The formation rate of growth ledges on the face-centered cubic/body- centered cubic interphase boundaries of facetted precipitates is measured in nickel-chromium alloys by hot stage transmission electron microscopy. Ledge formation rates predicted from classical nucleation theory are compared to those measured experimentally. The contributions of solute supersaturation, strain energy, and interphase boundary energy to ledge nucleation are assessed. The role of misfit dislocations at interphase precipitate/matrix boundaries during growth is determined. These results should provide a connection between the geometric approach to explaining precipitate shape employed by the invariant line model and the physical mechanism of precipitate growth.