[111]取向镍基单晶合金在蠕变期间组织演化的有限元分析

采用弹塑性应力-应变有限元方法计算了111]取向镍基单晶合金中γ/γ′两相共格界面的von Mises应力及应变能密度分布,研究了施加拉应力对γ/γ′两相界面von Mises应力分布及γ′相定向粗化规律的影响.结果表明:111]取向镍基单晶合金经热处理后,组织结构是立方γ′相以共格方式嵌镶在γ基体相中,沿(100)方向规则排列.当沿111]取向施加拉应力蠕变期间,与近(010)γ′晶面的基体通道相比,近(001)γ′和(100)γ′晶面的基体通道有较大的von Mises应力,在主应力分量的作用下,(100)和(001)晶面分别沿001],010]和010],100]方向发生较大的晶格扩张应变,可诱捕较大半径的Al和Ti原子,这是促使γ′相在(010)面沿001]和100]方向定向生长成为层片结构的筛网状筏形组织的主要原因.

MICROSTRUCTURE EVOLUTION AND FEM ANALYSIS OF[111]ORIENTED SINGLE CRYSTAL OF A NICKELBASED SUPERALLOY DURING TENSILE CREEP

The distribution of von Mises stress and strain energy density in regions near interfaces ofγ/γ’ phases was calculated by an elastic-plastic stress-strain finite element method (FEM),and the influences of applied stress on the von Mises stress distribution and coarsening regularity ofγ’ phase in a111]oriented single crystal nickel-based superalloy were also investigated. The results show that,after heat treated,the microstructure of the111]oriented single crystal superalloy consists of a cubicalγ’ phase embedded coherently inγmatrix,and the cubicalγ’ phase is regularly arranged along(100) direction.When tensile stress is applied along111] direction,compared to(010)_γ’ plane,larger expanding lattice strain occurs on(100)_γ’ and(001)_γ’ planes under the action of principal stress component,which may trap Al,Ti atoms with bigger radius to promoteγ’ phase directionally growing along010]and100]orientations on(010) plane, this is thought to be the main reason ofγ’ phase grown directionally into a mesh-like rafted structure along(010) plane.