冷却-等温-冷却处理过程硼的晶界偏聚

Grain Boundary Segregation of Boron during Cooling- Isothermal Holding-Cooling Process

用径迹显微照相技术研究了含硼 10× 10 - 6和 30× 10 - 6的 Fe- 40 % Ni合金在模拟冷却 -等温 -冷却处理过程后硼的晶界偏聚特征。结果表明 ,在从 115 0℃以 2℃ / s冷速分别冷却到 110 0℃ ,10 0 0℃ ,90 0℃ ,80 0℃和 70 0℃保温 2 min,然后再以 2℃ / s冷速冷却到 6 0 0℃水淬的冷却 -等温 -冷却过程中 ,硼在晶界会形成明显的偏聚 ,晶界偏聚量随等温温度的下降先有所减少后增加 ,最低值在 10 0 0℃左右出现。含硼 10× 10 - 6 合金在 80 0℃以上温度等温后冷到 6 0 0℃时 ,试样晶界偏聚包括连续硼偏聚带及一定量含硼析出相 ,其它试样沿晶硼偏聚带中硼主要以析出相形式存在。实验还观察到在晶内亚晶界上也有明显的硼偏聚存在 ,并在偏聚带两侧存在有贫硼区。在晶粒晶界与亚结构相交处 。

The grain boundary segregation of boron in Fe 40%Ni alloy with 10×10 -6 and 30×10 -6 boron during cooling isothermal holding cooling process was investigated by particle tracking autoradiography technique The results indicate that during cooling isothermal holding cooling process cooling from 1150℃ to 1100℃, 1000℃, 900℃, 800℃, 700℃ respectively at 2℃/s and isothermal holding for 2 min and then cooling to 600 ℃ at 2℃/s , the boron atoms segregate to grain boundaries obviously and the amount of segregating boron atoms first decreases then increases with the isothermal holding temperature decreased, and the lowest point is at about 1000 ℃ The grain boundary segregation of boron of samples with 10×10 6 boron isothermal holding at temperatures above 800℃ are mainly continuous pit belts with some amount boron precipitates, and that of the other samples are mainly boron precipitates It is also observed that obvious boron segregation exists on sub structures and boron depletion zone can be seen At the intersections of austenitic grain boundaries and sub grain boundaries, boron atoms preferably segregate to austenitic grain boundaries