Creep deformation related to dislocations cutting the γ' phase of a Ni-base single crystal superalloy

摘要

The microstructures of a Ru-containing single crystal superalloy have been characterized after creep deformation at 1000 ℃ under 270 MPa, 290 MPa and 310 MPa and at 1140 ℃ under 120 MPa, 137 MPa and 150 MPa. Detailed analysis demonstrates that the width of the rafted y' phase at 1140 ℃ is wider than that at 1000 ℃. The gradually disappeared γ matrix has been observed at 1000 ℃ in the ruptured specimens; however, this case has been rarely observed at 1140 ℃. On the other hand, the topological inversion has taken place under present creep conditions. Furthermore, under all the creep conditions conducted in this work, the a_0 <010> superdislocations in the γ' phase have been observed in this experimental alloy. These superdislocations usually possess non-compact core which consists of two a_0/ 2<101> dislocations with different Burgers vectors. At 1000 ℃, only the long dislocations which mainly orientate the <110> directions (dislocation line direction) have been observed; however, at 1140 ℃, both the long and zigzag (partial with non-compact core and mainly orientated the <101> and <101> directions) superdislocations have been observed. Apart from that, a special superdislocation with two segments of compact core and two segments of non-compact core has been observed, which has been rarely reported previously. At last, a very interesting observation is that a superdislocation array presents in the rafted γ' phase after creep at 1140 ℃ under 150 MPa. The formation process and configuration of this dislocation array have been analyzed in detail, which has also been rarely reported previously.