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利用SEM和物理化学相分析方法研究了5种Hf含量的FGH97粉末高温合金中γ’相和MC型碳化物形貌、化学组成及含量.结果表明:Hf促进γ’相和MC相析出,改变γ’相和MC相的化学组成,对MC相的尺寸和形貌影响不大,显著影响γ’相的尺寸和形貌,促使γ’相的形态失稳,导致立方状γ’相发生分裂,使γ’相更快地进入稳定的立方状择优形态.在FGH97合金中添加Hf,可通过改变错配度d,从而改变γ’相发生分裂的临界尺寸Dc.建立了Dc与Hf含量w(Hf)的关系式:Dc=315.4+640.2w(Hf)-358.2[w(Hf)]2.随着Hf含量的增加,|d|逐渐变小,Dc增大.γ’相长大到临界尺寸时,γ’相由立方状分裂为八重小立方体状.
The morphology, chemical composition and content of γ ’phase and MC type carbides in five Hf FGH97 powder superalloys were studied by means of SEM and physical-chemical phase analysis. The results show that Hf can promote the precipitation of γ’ phase and MC phase, The chemical composition of γ ’phase and MC phase has little effect on the size and morphology of MC phase, and significantly affects the size and morphology of γ’ phase, which leads to the instability of γ ’phase and the splitting of cubic γ’ phase , So that the γ ’phase into a more stable cubic shape preferential morphology in the addition of Hf FGH97 alloy, by changing the degree of mismatch d, thereby changing the γ’ phase split critical size Dc established Dc and Hf content w (Hf): Dc = 315.4 + 640.2w (Hf) -358.2 [w (Hf)] 2. As the content of Hf increases, | d | becomes smaller and Dc increases. At the critical dimension, the γ ’phase is split into cuboid cubes by a cubic shape.