析出相对GH4141合金蠕变持久断裂行为的作用机制

Effect of precipitates on the creep rupture behavior of GH4141 superalloy

研究了析出相与GH4141合金蠕变持久断裂行为的交互作用,涉及蠕变裂纹萌生和扩展。表征手段采用二次电子和电子背散射衍射技术,重点关注了析出相(包括MC、M_(6)C、M_(23)C_(6)型碳化物和γ′弥散强化相)、孔隙和晶界裂纹,同时分析了晶粒塑性变形和强化机制。孔隙主要发生在晶界与M_(6)C和M_(23)C_(6)碳化物的界面处,相邻孔隙聚合形成涟漪形貌,裂纹生长加剧了其前端区域的塑性变形。晶粒内部强化涉及γ′析出相对位错运动的抑制,由于应变激活多个滑移系统,加快了位错塞积和缠结现象,起到强化晶粒的效果。

This study focused on the effect of precipitates on the creep rupture behavior of GH4141 superalloy,involving creep crack initiation and propagation.Microstructures including carbides,γ′precipitate hardening phase,void and intergranular crack were characterized by SE and EBSD.Meanwhile,plastic deformation and hardening mechanisms for crystal grains were analyzed.Voids occurred at the interfaces of grain boundary and carbides.Voids coalescence with wavy morphology were observed.The increase in crack length enhanced plastic deformation degree in front of the crack tip.The crystal grain strengthening was caused by the suppression of dislocation motion resulting from γ′pinning effect.Due to the activation of multiple glide systems,dislocation piled up and tangled to enable crystal grain strengthening.