定向凝固钴基高温合金的低周疲劳行为──Ⅰ.室温疲劳及其机制

LOW CYCLE FATIGUE BEHAVIOR OF A DZX40M DIRECTIONALLY SOLIDIFIED Co-BASED SUPERALLOY──Ⅰ.Fatigue and Its Mechanism at Room Temperature

对一种定向凝固的钴基高温合金（DZX40M）在总应变控制下，在室温进行低周疲劳实验，结果显示：循环硬化出现在循环应力曲线的头几周，随即被在疲劳寿命中占主导地位的饱和阶段所代替。TEM分析表明：室温的起始硬化是由于层错交割对层错运动的阻碍引起层错塞积所致、室温的饱和阶段是（111）面上的层错转化为（111）面的密排层错带造成的。

Low cycle fatigue behavior of a DZX40M directionally solidified Co-based superalloy has been investigated at room temperature in air under different total strain amplitudes ranging from 2.5 × 10(-3) to 6.0 × 10(-3). The results show that the cyclic hardening of the alloy appears at the first few cycles in the initial hardening stage, and then the saturation stage which is the major part of the whole fatigue life begins. Examination by TEM indicates that the initial hardening of the alloy is caused by the pile-up of the stacking faults at the intersection of stacking fault, while the saturation of the alloy during low cycle fatigue is arising from the transition of the stacking fault on the (111) to the closely spaced stacking fault ribbon on the (111).