单晶高温合金中γ′筏形组织的形成及转动

FORMATION AND ROTATION OF γ' RAFTS IN Ni-BASE SINGLE CRYSTAL SUPERALLOY NASA IR100

研究了ＮＡＳＡＩＲ１００单晶在高温持久变形中γ′筏形组织的形成及其在缩颈区内的转动，发现γ′沉淀在持久变形初期即沿着垂直于拉伸应力轴的方向相互连结，变形大约５０ｈ后形成了完善的γ′筏形组织，对拉断试样的纵截面进行了扫描电镜观察，发现缩颈区内的γ′筏形组织不再垂直于应力轴，而是绕着应力轴转动，初步提出了γ′筏形组织的形成及转动机理。

The formation of γ' rafts and their rotation in the necking zone during high temperature stress-rupture tests of NASA IR100 single crystal superalloy were investigated.It was found that γ' precipitates linked each other in the direction of perpendicular to the stress axis just after the beginning of the stress-rupture test. Perfect and regularγ' rafts formed when the stress-rupture test lasted for about 50 h. After observing the longitudinal sections of ruptured bars by SEM the γ' rafts in the necking zones were found to be not perpendicular to the stress axis, but rotated around the stress axis. The mechanisms of γ' raft formation and rotation were put forward in this paper.