【摘要】 对[001]取向单晶镍基合金进行压应力处理,获P-型筏状结构后,对其进行拉伸蠕变性能测试及SEM形貌观察,研究了P-型筏状结构的粗化特征及影响因素。结果表明:由于应力场的差别,样品不同位置筏状γ′相粗化程度及特征不同,近断口处筏状γ′相扭曲且粗化程度加剧,随离断口距离增加,γ′相粗化程度减弱。有限元分析认为:外加载荷改变了水平和垂直γ基体通道中的错配应力分布,并使立方γ′相不同界面晶格发生挤压或扩张应变,这可以促进元素的互扩散和γ′相的定向生长,是形成P-型筏状组织的主要原因。在高温及拉应力作用下,P-型γ′相端部沿垂直于应力轴方向优先生长和相互横向连接,并进一步形成折叠的层状组织。更多还原

【Abstract】 Coarsening features and influence factors were investigated by creep properties measurement and SEM observation for the P-type rafted structure of nickel base single crystal superalloy with [001] orientation obtained by compressive creep.Results showed that various coarsening features were displayed at different regions of the tensile sample due to the difference of stress field.The γ ’ rafts near the fracture displayed a heavily twisted and coarsened feature,but less pronounced far from the fracture.Finite elements analysis indicated that the applied loading changed the distribution of misfit stress within the vertical and horizontal matrix channels,and resulted in the extrusion or expansion strain of lattices on the different interfaces of cubic γ ’ phase.It may promote the elements diffusion and directional growth of γ ’ phase to form the P-type rafted structure.The P-type γ ’ phase edge grew prior to the direction perpendicular to the stress axis and linked each other to form a layer structure with folded feature at high temperatures and in tensile stress fields.更多还原