两次时效GH80A合金的组织特征

Microstructure Characteristic of GH80A Alloy Treated with Two Aging Process

采用光学显微镜和透射电镜观察了两次时效的GH80A合金的显微组织 ,其特征为 :①晶内存在大小两种尺寸的γ′ ;②晶界析出不连续的近球形M2 3C6碳化物 ;③晶界存在尺寸较大的γ′相。

:GH80A is a typical nickel base superalloy.It is wide used in turbine engine for aeroplane and power plant.But GH80A treated with standard heat treatment process 1080℃×8h AC+700℃×16h AC has severe notch sensitivity.Exeperiments show that solid solution plus two aging heat treatment can eliminate the notch sensitivity of GH80A.Microstructure of GH80A treated with two aging heat treatment was observed with optic microscope and transmission electron microscope.The results show that,① there are two types of γ′ (larger cubes and smaller particles)phase precipited in innergrain;② near sphere like M 23 C 6 carbide are precipited in grainboundary discontinuously;③ there exist larger cuboid γ′ phase in grainboundary.It is proposed that the above microstructure characteristic is the main contribution to the excellent properties of GH80A treated with two aging heat treatment process.