FGH95粉末镍基合金组织结构对蠕变机制的影响

Influence of Microstructure on Creep Mechanism of FGH95 Powder Ni-based Superalloy

通过对热等静压态FGH95合金进行完全热处理、组织形貌观察、点阵常数测定和蠕变曲线测定,研究了FGH95镍基合金的组织结构和蠕变机制。结果表明:合金经热等静压成型后,粗大相沿原始颗粒边界不连续分布,经高温固溶和时效处理后,晶粒尺寸无明显变化,粗大相数量减少,且细小相和MC碳化物在合金中弥散析出,可提高合金蠕变抗力,同时由于相形成元素Al、Ti溶入基体,经XRD谱线测定,相的平均点阵常数减小,而基体相平均点阵常数增加,致使/两相晶格错配度减小;在实验温度和应力范围内,测得合金的蠕变激活能为630.4kJ/mol。在蠕变期间,FGH95合金的蠕变机制是位错在基体中运动或剪切相,其中,蠕变位错以Orowan机制绕过相,而<110>超位错切过相发生分解形成(1/3)<112>超肖可莱不全位错+层错的位错组态。

The microstructure and creep mechanisms of FGH95 nickel-base superalloy were investigated by full heat treatment, microstructure observation, lattice parameters determination and creep curves. Results show that after the alloy is HIP treated, coarse γ＇ phase discontinuously distribute along the previous particle boundaries. After solution treatment at high temperature and twice aging, the grain size has no obvious change, and the amount of coarse γ＇ phase decreases. Moreover, the fine γ＇ phase and MC carbides dispersedly precipitate in the grain, which can enhance the creep resistance of the alloy. Because the formation elements of γ＇ phase （Al and Ti） are dissolved into the γ matrix, the lattice parameter of γ＇ phase increases while the g phase decreases at the same time by XRD spectral line measurement, which results in the lattice misfit of γ/γ＇ phases decreasing. In the ranges of experimental temperatures and applied stresses, the creep activation energy is about 630.4 kJ/mol. During creep, the mechanisms of FGH95 alloy are dislocation moving in the matrix or shearing into the γ＇ phase. Thereinto, the creep dislocations move over theγ＇ phase by Orowan mechanism; however, the 〈110〉 super-dislocation shearing into the γ＇ phase is decomposed to form the configuration of （1/3）〈112〉 super-Shockleys partials plus the stacking fault.