一种单晶镍基合金蠕变期间γ'相的定向粗化机制

A DIRECTIONAL COARSENING MECHANISM OF THE γ＇-PHASE DURING CREEP OF A SINGLE CRYSTAL NICKEL-BASE SUPERALLOY

对[001]取向单晶镍基合金恒载拉伸蠕变不同阶段的组织形貌进行了SEM，TEM观察和EDAX成分分析，研究了γ＇相定向粗化过程及机理结果表明：蠕变初期，两相邻γ＇相呈侧平面对接方式，沿垂直于应力轴方向定向生长为类似筛网的核状组织，外加应力使γ＇／γ界面共格应变减少，应变能降低，释放的能量是促使合金元素定向扩散形成筏状γ＇结构的驱动力．

The microstructures of a [001] single crystal nickel--base superalloy at differentstages of the constant loading tensile creep were observed by means of TEM and SEM, and thechemical compositions of γ and γ＇ phases were analyzed by EDAX in order to investigate theprocess and mechanism of the directional coarsening of γ＇ phase. The results showed that themesh--like rafts were formed along the direction normal to the stress axis in a mode of side--planelink in primary creep. The applied stress resulted in the decrease of the coherent strain and theenergy of the γ＇/γ interfaces. Thus, the energy released was supposed to be the driving force forthe directional diffusion of elements, leading to the formation of the γ＇ rafts.