GH220合金中晶界针状碳化物的成因

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。

Research on Formation Rule of G.B. Plate-Like Carbide in GH220 Ni-Base Wrought Superalloy

The transition process of grain boubary (G.B.) plate-like carbides have been researched in a Ni-base wrought superalloy under cyclic creep condition of temperature 1123 K, stress 392 MPa and hold time 8 (min). Its formative rule has been analyzed. Two kinds of different heattreatment method are used for getting different kinds of G.B. alloy, (straight G.B. and zigzag G.B.). The results of TEM analysis show that there are same process of transition particle carbides to plate-like carbides in both of G.B. alloy. There is a transition process from zigzag G.B. to straight G.B. before above process, i.e. the greater carbides which is not rule in size are broken up to particle G.B. carbides, (or straight process in brief). This process would take a long time. And so, the reason has been explained that plate-like carbides of zigzag G.B alloy are less than that of straiht G.B. alloy. A mode of transition zigzag G.B. to straight G.B. and of transition particle carbides to plate-like carbides is assumed in this paper.