中文摘要：

对原始T91钢及在650℃下时效50-1700h的T91钢试样进行SEM观察以及能谱分析，着重对析出相进行了分析。结果表明；在时效过程中。析出相主要沿晶界析出，析出相主要由铬、钼元素组成，析出物颗粒总数随时效时间增加呈先减少后增加再减少的变化规律，析出相颗粒的尺寸则是先增大后减小最后球化长大的规律，析出相面积分数随着时效时间延长符合二次函数变化规律。

英文摘要：

The original specimen of T91 and specimens aged for 50-1 700 h at 650 ℃ were studied by scanning electron microscopy （SEM） and energy dispersive spectrometer（EDS）, and their precipitated phases were analyzed as a key point. Results show that the phases precipitated along grain-boundfiry were composed of Cr and Mo mainly; the account of precipitated phase firstly decreased, then increased, and decreased again; the average size of precipitated phase firstly increased, then decreased and spheroidized finally; the relationship between area fraction of precipitated phase and aging time fittd well with a ,quadratic function.