新型Cr18Ni31NbAl铁镍基合金的高温蠕变行为

High Temperature Creep Behavior of New Type Fe-Ni Based Cr18Ni31NbAl Alloy

研究了新型Cr18Ni31Nb Al铁镍基合金650℃时在不同应力条件下的蠕变性。结合OM、SEM及TEM等表征手段,对该合金在650℃、280 MPa下蠕变各个阶段进行分析。结果表明:在蠕变初始阶段,基材上出现少量析出物;稳态蠕变阶段析出物明显增多且位错增殖;破坏阶段,第二相粗化显著、位错减少。蠕变过程中晶界附近析出大量M_(23)C_6(Cr为主),晶内沉淀细小NbC颗粒,这种弥散析出物有效提高了合金的蠕变强度。断口微观形貌为颗粒状脆性断口,属于典型的沿晶断裂。

Th e creep behaviors of new Fe-Ni based alloy Crl8Ni31NbAI under different stress at 650℃ were investigated. Three stages of creep behaviors at 650℃, 280MPa were investigated using OM, SEM, and TEM. The results show that a few of precipitates distribute uniformly on the matrix when the creep begins. At steady-state stage, the dislocations and precipitates increase significantly. During the failure stage, the secondary phase coarsenes significantly, accompanied with the decrease of dislocations. Additionally, it is found that there are （Cr,Fe）23C6 particles and fine NbC particles precipating around grain boundary in creep, which can remarkably improve the creep strength of Crl8Ni31NbAI alloy. The micro-morphology of fracture is granulated brittle fracture and it belongs to the typical intergranular fracture.