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研究Hf含量为0.34%和0.10%Hf的第二代单晶高温合金DD6在700°C的高周疲劳行为;采用扫描电镜对疲劳裂纹的萌生与失效机制进行分析,采用透射电镜研究变形后的显微组织。结果表明:含0.34%Hf的DD6合金比含0.10%Hf的合金的疲劳寿命稍有降低;疲劳裂纹萌生于试样表面、亚表面,沿{111}面扩展,而并不沿垂直应力轴方向扩展;断口上有典型的疲劳条带;Hf含量为0.34%和0.10%的DD6合金的高周疲劳断裂机制为类解理断裂。透射电镜分析表明,合金在循环变形中形成了不同形式的位错。
The high cycle fatigue behavior of the second generation single crystal Superalloy DD6 with Hf content of 0.34% and 0.10% Hf at 700 ° C was studied. The mechanism of fatigue crack initiation and failure was analyzed by scanning electron microscopy. Microstructure. The results show that the fatigue life of DD6 alloy containing 0.34% Hf is slightly lower than that of alloy containing 0.10% Hf. The fatigue crack initiation occurs on the subsurface and the {111} plane of the sample, not along the direction of the vertical stress axis The fatigue cycles of the DD6 alloy with Hf content of 0.34% and 0.10% are type-cleavage fracture. Transmission electron microscopy analysis showed that the alloy formed different forms of dislocations in the cyclic deformation.