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本文用电子金相观察了GH49合金两种不同的晶界状态,试样在蠕变断裂过程中位错组态的变化,并研究了位错与晶内γ′相及晶界碳化物沉淀间的相互作用。研究表明:平直晶界试样,晶内蠕变主要是位错攀移越过γ′相所引起,晶界运动受控于晶界滑动。而弯曲晶界试样,晶内蠕变是位错攀移越过r′相及位错切割γ′相所引起,晶界运动受控于晶界滑动与弯曲段内的“回复”移动。因而,弯曲晶界提高了晶内蠕变速率而降低了晶界滑动速率。这就有效地阻止了裂纹的连接、扩展,大幅度地提高了蠕变第三阶段的断裂抗力,从而延长了蠕变寿命及蠕变断裂塑性。
In this paper, two different grain boundary states of GH49 alloy were observed by electron metallography, and the dislocation configurations of the samples were observed during creep rupture. The relationship between dislocation and intragranular γ ’phase and intergranular carbide precipitation Interaction. The results show that the grain creep in the flat grain boundary is mainly caused by the displacement of the disordered γ ’phase, and the grain boundary movement is controlled by the grain boundary sliding. However, the grain boundary creep is caused by the displacement of the dislocation across the r ’phase and the γ’ phase of the dislocation cutting, and the grain boundary movement is controlled by the “recovery” movement within the grain boundary sliding and bending sections. Thus, bending the grain boundaries increases the intragranular creep rate and decreases the grain boundary slip rate. This effectively prevents the crack from being connected and expanded, improves the fracture resistance in the third stage of creep drastically, and prolongs the creep life and creep rupture plasticity.