摘要
采用相同的熔炼工艺和定向凝固工艺,制备了直径分别为15mm和30mm的单晶高温合金圆柱形试样,测试了两种铸件尺寸合金在980℃/250MPa的持久性能和800℃的高周疲劳性能。采用光学显微镜、扫描电子显微镜与透射电子显微镜对不同直径单晶铸件试样的枝晶形貌、铸态与热处理γ′相组织、显微孔洞、持久与高周疲劳断口和断裂组织进行了研究。结果表明:随着铸件尺寸增大,合金的一次枝晶间距增加,铸态组织和热处理组织中γ′相尺寸增大,显微孔洞数量和尺寸增加;同时,合金在980℃/250MPa条件下的持久性能降低,其断裂机制无明显变化,均为韧窝断裂;随着铸件尺寸增大,持久断裂组织中显微裂纹数量和尺寸增加,γ′相筏排厚度增加,合金的高周疲劳性能降低,其断裂机制均为类解理断裂。最后讨论了合金性能与其显微组织的关系。
The cylindrical specimens of a single crystal superalloy with diameter of 15mm and 30mm were prepared using the same melting process and directional solidification process.The stress rupture properties at 980℃/250MPa and high cycle fatigue properties at 800℃of the alloy with two casting dimensions were tested.Dendrite microstructure,the as-castγ′phase,heat treatedγ′phase,micropore,stress rupture and high cycle fatigue fractograph and fracture microstructure of the alloy with different casting dimension were examined by OM,SEM and TEM.The results show that with the increase of casting dimension,the primary dendrite arm spacing,the size of as-cast and heat treatedγ′phase,and the size and volume fraction of micropore increase.The stress rupture properties of the alloy decrease,the fracture mechanism has no obvious change and is dimple model with casting dimension increasing.The quantity and size of micro-crack and theγ′raft thickness on the stress fracture microstructure increase with the casting dimension increasing,while high cycle fatigue properties of the alloy decrease.At last,the relationship between the property and microstructure of the alloy is discussed.
作者
刘晓功
姜楠
郝齐赞
罗亮
史振学
骆宇时
LIU Xiao-gong;JIANG Nan;HAO Qi-zan;LUO Liang;SHI Zhen-xue;LUO Yu-shi(Science and Technology on Advanced High Temperature Structural Materials Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,China;Aviation Military Representative Office of Military Aviation Bureau of the Army Equipment Department in Beijing,Beijing 100012,China)
出处
《真空》
CAS
2022年第3期80-85,共6页
Vacuum
关键词
单晶高温合金
铸件尺寸
显微组织
性能
single crystal superalloy
casting dimension
microstructure
property
