镍基单晶合金基体相γ在不同应力状态蠕变的扩散分析

Diffusing Analysis of Matrix γ in Nickel-base Single Crystal Superalloy During Different Stress Creep

对镍基单晶合金材料DD3的[001]取向试样进行950℃、278 MPa/250 MPa两种载荷水平的3个时间阶段的单轴拉伸蠕变试验。采用扫描电镜(SEM)观察各试验阶段试样的γ/γ'两相微观组织。通过抽样统计得到基体相γ通道水平宽度在三个蠕变时间阶段的概率密度函数,其概率分布服从对数正态分布。分析了在同一温度下两种载荷水平对γ相水平宽度变化的影响,并结合蠕变寿命曲线分析了微观γ相水平宽度与蠕变时间的函数关系。结果表明,外加载荷是影响基体相γ通道水平宽度增长速率的重要因素,但对在蠕变断裂后最终的γ相宽度值的影响不显著。

The tensile creep tests of a nickel-base single crystal superalloy DD3 were carried out under the condition of 950 ℃ and 278 MPa/250 MPa load.The microstructure of γ/γ ＇ phase at different creep stages was observed by SEM.The probability distribution of the γ-channel width during different stress creep was obtained by sampling microstructure pictures of the γ/γ ＇ phase,which follows lognormal distribution.The influences of two stresses on the γ-channel width were analyzed.Considering to the creep life curves,the change trend of microcosmic γ-channel width during stress creep was analyzed.The results show that the applied stress is one of the important factors that affects the growth rate of the γ-channel width,but in-apparently affects the last γ-channel width after creep fracture.