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通过蠕变性能测试、组织形貌观察及位错组态的衍射衬度分析,研究了镍基单晶高温合金在中温/高应力稳态蠕变期间的变形机制.结果表明,在760℃,760 MPa和800℃,650 MPa蠕变期间,剪切g′相的位错可发生分解,分解后领先的a/3<112>超点阵Shockley不全位错切入g′相,拖曳的a/6<112>Shockley不全位错滞留在g′/g相界面,2个不全位错之间形成超点阵内禀堆垛层错(SISF);此外,剪切进入g′相的超点阵位错可由{111}面交滑移至{100}面,形成具有非平面位错芯结构的K-W锁,可抑制位错的滑移和交滑移,提高合金的蠕变抗力.在850℃,500 MPa蠕变期间,合金中的层错消失,部分剪切进入筏状g′相的a<110>超点阵位错可分解形成“2个a/2<110>不全位错加反相畴界(APB)”的组态,而合金中K-W锁的消失是由高温热激活致使立方体滑移的位错重新交滑移至八面体所致.
The deformation mechanism of nickel base single crystal superalloy during steady-state creep at medium temperature / high stress was studied by means of creep test, microstructure observation and diffraction contrast analysis of dislocation configurations. The results show that at 760 ℃, The dislocations of the cleaved g ’phase can be decomposed during 760 MPa, 800 ° C and 650 MPa creep. The dislocated Shockley dislocated into the g’ phase after the decomposition of the leading a / 3 <112> superlattice, the a / 6 <112> Shockley incompletely stagnates at the g ’/ g interface and forms a super-lattice intrinsic stacking fault (SISF) between two incomplete dislocations. In addition, shearing enters the g’ phase superlattice The dislocations can be cross-linked from the {111} plane to the {100} plane to form a KW lock with a non-planar dislocation core structure, which can suppress the slip and cross-slip of dislocations and improve the creep resistance of the alloy. During 500 MPa creep, the stacking faults in the alloy disappear and a <110> superlattice dislocations that partially shear into the raft g ’phase can decompose to form “2 a / 2 <110> Anti-phase boundary (APB) ”configuration, and the disappearance of the KW lock in the alloy is caused by the high-temperature thermal activation resulting in dislocations of the cube sliding back to the octahedron.