通过进行蠕变曲线测定和组织形貌观察,研究了FGH95粉末镍基合金的微观组织结构与蠕变行为.结果表明:合金经高温固溶、盐浴冷却处理后,组织结构是由细小的γ′相弥散分布在γ基体所组成,其细小(Nb,Ti)C碳化物在晶内及沿晶界不连续析出.在试验的温度和施加应力范围内,合金表现出明显的施加温度敏感性,并测算出合金在稳态蠕变期间的蠕变激活能和应力指数分别为Q=542.07kJ/mol和n=14.8.合金在蠕变期间的变形特征是孪晶和位错在晶内发生双取向滑移,其切入γ′相内的<110>超位错可分解形成(1/3)<112>超肖克莱不全位错+层错的位错组态,发生孪晶变形的孪晶面为(111)晶面.晶界及沿晶界不连续析出的细小(Nb,Ti)C型碳化物可有效阻碍位错运动,是使合金具有较高抗蠕变能力的主要原因.
By means of the measurement of creep curves and microstructure observation, an investigation has been made into the microstructure and creep behaviors of FGH95 powder nickel-base superalloy. Results show that, after solution treated, microstructure of the alloy consists of the finer γ′ phase and γ matrix, and the finer (Nb,Ti)C carbide particles is discontinuously precipitated within the grains and grain boundaries. In the range of the applied temperatures and stresses, the alloy displays an obvious sensibility of the applied temperatures, and the creep activation energy and stress exponent of the alloy during steady state stage are calculated to be Q=542.07kJ/mol and n=14.8, respectively. The deformation mechanism of the alloy during creep is that the double orientation slipping of dislocation are activated in the alloy. The <110> super-dislocation which shears into γ′ phase may be decomposed into two of (1/3)<112> super-shockleys dislocation to form the dislocation configuration of the partial+stacking fault. And in the further, the twinning plane activated during twinning deformation is determined as (111) plane. The boundaries and (Nb,Ti)C carbide particles which is discontinuously precipitated along the grain boundary may effectively hinder the movement of dislocation, which is thought to be one of the main reasons for the alloy displaying a better creep resistance.
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