摘要
为研究γ'相定向粗化现象,采用有限元方法(FEM)计算了单晶 Ni基γ和γ'双相合金有/无外加载荷时的热错配应力及应变能密度.结果表明:外加载荷改变了γ和γ'相内的von Mises应力及应变能密度分布,与弹性应变相联系的共格应变能变化是γ'相定向粗化的驱动力.外加拉伸或压缩应力,引起立方γ'相不同界面晶格发生挤压或扩张应变,晶格的挤压应变可排斥γ'相中原子半径较大的AI,Ta等溶质元素;扩张的晶格可诱捕这些元素,以促进γ'相的定向生长,因此,沿(100)方向扩张晶格的法线方向是γ'相形筏的生长方向.随γ'相弹性扩张晶格应变及γ相粘滞塑性流变的增加,元素扩散及γ'相形筏速率提高。
By means of finite elements analysis, an investigation has been made for the directional coarsening of γ' precipitates in a single crystal nickel-base superalloy with [001] orientation during tensile or compressive creep at 1040℃.Results show that the strain energy change related to the elastic strain in the cubic γ'phase is the driving force for the γ'rafting. The elastic strain in the cubic γ' lattice results in the solid solubility change of the elements Ta and Al with bigger atomic radius. The extrusion or expansion strain in the lattice of the cubic γ' interfaces may repel or trap these atoms to promote the directional growth of the γ' phase.The normal direction of the enlarging lattice is the growing one of the γ' rafts.The rafting rate of γ' is enhanced with the increase of the viscoplastic flow in the γ phase and the elastic strain in the γ' phase, respectively.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2000年第5期465-471,共7页
Acta Metallurgica Sinica
关键词
单晶Ni基高温合金
蠕变
定向粗化
有限元
γ'相
single crystal nickel-base superalloy,creep,directional coarsening, FEM analysis