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研究了镍基高温合金在1123K,392MPa下周期持久断裂过程中晶界针状碳化物的析出过程。分析了它的形成原因,实验采用二种热处理工艺,得到二种不同的晶界状态:直晶和弯晶。透射电镜分析结果表明,无论何种晶界状态,晶界碳化物都有一个由颗粒状碳化物向针状碳化物转化的过程。而弯晶处理的合金,首先发生由弯晶向平直晶界的转变,即尺寸较大且不规则状的晶界碳化物逐渐断裂成颗粒状排列的晶界碳化物,该过程所需时间较长,这就解释了弯晶合金比如直晶合金针状碳化物量少的原因。提出了一个由颗粒状碳化物向针状碳化物转化的模型。
The precipitation process of the grain boundary carbides during the permanent fracture of the Ni-base superalloy at 1123K and 392MPa was studied. The reasons for its formation were analyzed. Two kinds of heat treatment processes were used in the experiment, and two different grain boundary states were obtained: straight grain and bent grain. Transmission electron microscopy results show that, regardless of the grain boundary state, the grain boundary carbides have a transformation from granular carbides to acicular carbides. In the case of the as-bent alloy, the transformation from the bent crystal to the flattened grain boundary occurs first, that is, the large and irregularly shaped grain boundary carbides gradually break into grain-like grain boundary carbides, and the time required for the process Longer, which explains the reason for the small amount of acicular carbide such as straight-chained alloys. A model for the conversion of granular carbides to acicular carbides is proposed.