材料期刊网

研究了［００１］取向单晶高温合金ＣＭＳＸ—４在１２５３Ｋ，３５０ＭＰａ拉伸蠕变中γ＇沉淀沿垂直于外应力轴方向的粗化过程及其机理。发现在定向粗化期间立方形γ＇沉淀的边缘部分优先生长，γ—γ＇界面呈内凹形方式推进，进而封闭了与之相邻的垂直基体通道（平行于［００１］）；相互连接的γ＇沉淀逐渐消耗并最终耗尽被封闭的残余垂直通道而发展成完整的筏形组织。定向粗化导致了γ＇沉淀沿［００１］方向的尺寸逐渐减小，水平基体通道（垂直于［００１］）的宽度大幅度增加。对γ＇沉淀的特殊生长方式和两共格相形貌的演变特征进行了分析与讨论。

The coarsening of γ'precipitates along the direction perpendicular to the externally applied stress axis was investigated for [001]-oriented single crystal superalloy CMSX-4 under 1253 K, 350 MPa tensile creep test. It is found that the portion of edge areas of cuboidal γ'precipitates grew preferentially and the γ-γ'interfaces progressed concavely,which was followed by the enclosure of the adjacent vertical matrix channels (parallel to [001]), and the linked γ'precipitates gradually exhauseted the retained vertical channels and finally developed into rafted plates. The directional coarsening led to a decrease in the size of γ'precipitates in the [001] direction and to an increase in the width of the horizontal matrix channels (perpendicular to[001]). The specific growth manner of the γ'precipitates and the characteristics of the morphological evolution of the two coherent phases in the tested samples are discussed.