FGH95粉末镍基合金的组织结构与蠕变特征

Microstructure and Creep Features of FGH95 Powder Nickel-base Superalloy

通过蠕变曲线的测定及组织形貌的观察,研究了FGH95粉末镍基合金的蠕变行为及变形特征。结果表明:FGH95粉末镍基合金在试验的温度和应力范围内,具有明显的施加温度和应力敏感性,并测算出合金的蠕变激活能和应力指数。合金的组织结构由一次、二次、三次γ′相及弥散分布的碳化物组成,在粉末颗粒之间具有较宽的晶界。蠕变期间,在合金晶粒内的变形以单取向或双取向滑移方式进行,并在滑移迹线附近有细小碳化物析出,而较宽的晶界由于剧烈变形可发生碎化形成细小晶粒。合金在蠕变期间的微观变形机制是位错发生双取向滑移,其中(1/2)〈110〉位错在γ基体相中运动,〈110〉超位错存在于γ′相内,而层错的形成是由于〈110〉超位错分解为(1/3)〈112〉超肖克莱不全位错所致。

By means of the measurement of creep curves and microstructure observation,an investigation has been made into the creep behaviors and deformation features of FGH95 powder nickel-base superalloy.Results show that,in the range of the experimental temperatures and stresses,FGH95 powder nickel-base superalloy displays an obvious sensibility of the applied temperatures and stresses.Microstructure of the alloy is made up of the various sizes γ′ phase and carbide particles,and the wider grain interfaces situated in between the powder particles.During creep,the single orientation and double orientations slipping are activated within the grains of the superalloy,and the finer carbide particles are precipitated near the regions of the slipping trace lines.The original grain interfaces with the wider size are made into the finer grains due to the effect of the bigger deformation.The deformation mechanism of the superalloy during creep is that the double orientation slipping of dislocation are activated in the alloy,including that(1/2)〈110〉 dislocation and 〈110〉 super-dislocation are activated,respectively,within the γ matrix phase and the γ′ phase.In the further,it is the reason of the stacking fault contrast appeared in the alloy that the 〈110〉 super-dislocation is decomposed into(1/3)〈112〉 super-shockleys dislocation,which results in the formation of the stacking fault.