蠕变镍基单晶高温合金微观结构与界面特征的X射线小角散射研究

摘要

The two-dimensional scattering patterns for micro-structural changes during creep observed by SAXS are different from that obtained by SANS technique. The changes in morphology and size characteristics of different regions of the secondary γ＇ precipitates have been demonstrated by the variation of SAXS scattering intensity. The results show that the secondary γ＇ precipitates have two types of feature sizes, which have similar trends of change during the creep process characterized by decreasing in the first and second stage and increasing in the final stage. As comparison shows, the larger γ＇ precipitates have more noticeable changes. The elements of the secondary γ＇ precipitates diffuse seriously in the second stage with the character of creep 15 h, the surfaces of γ＇ phase are blurred, and interfaces of two-phase become clear again in the final stage. Due to the increasing size or the reducing number of the secondary γ＇ phase, the total ares of interfaces between the secondary γ＇ precipitates and matrix phase then decreases.%利用SAXS技术对蠕变过程中不同尺度范围的微观结构变化分析表明X射线小角散射(SAXS)与中子小角散射(SANS)测量的二维散射图具有明显的差异,由散射强度曲线的变化说明了蠕变过程中二次析出γ'相形貌和不同区域尺寸特征的改变情况.分析结果表明二次析出γ'相存在两类特征尺寸,在蠕变过程中沿[100]或[010]方向的变化趋势类似,均是在第一和第二阶段有所减小,在第三阶段又有所增大,相较而言,特征尺寸较大的γ'相变化也较为显著.二次析出γ'相在蠕变第二阶段元素扩散最严重,相表面最粗糙,在第三阶段两相界面又进一步明锐;进一步分析表明随蠕变时间增加由于颗粒增大或总量减小,二次析出γ'相与基体相的界面总面积逐渐减小.