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利用微观组织分析及化学相分析的方法研究了9种不同Mo、W含量的汽轮机叶片用GY200镍基合金中碳化物及γ’强化相的析出规律。结果表明,合金中出现MC、M_6C、M_(23)C_6型碳化物,MC相由一次未溶TiC和少量二次析出的TiC组成,MC相含量随W、Mo添加量增加而增加。M_6C在1080℃就开始析出,对于GY200镍基合金,M_6C析出条件可由Cr/(Cr+Mo+0.7W)≤0.847(at%)经验公式来表达。Mo添加后,M_(23)C_6含量随W添加量的增加有减少趋势。Mo促进TCP相析出的动力学比W元素的要强,利用W来替代部分Mo,能够减少Laves相、TCP相的析出。W添加4%以内将明显改善合金高温强塑性。
The precipitation regularities of carbides and γ ’strengthening phases in GY200 nickel-base alloy for steam turbine blades with nine different Mo and W contents were studied by means of microstructure analysis and chemical phase analysis. The results show that MC, M_6C and M_ (23) C_6 carbides appear in the alloy. The MC phase consists of primary undissolved TiC and a small amount of secondary precipitated TiC. The content of MC phase increases with the addition of W and Mo. M_6C begins to precipitate at 1080 ℃. For GY200 nickel base alloy, M_6C precipitation condition can be expressed by empirical formula of Cr / (Cr + Mo + 0.7W) ≤0.847 (at%). With the addition of Mo, the content of M_ (23) C_6 tends to decrease with the increase of W content. The kinetics of the TCP phase precipitation promoted by Mo is stronger than that of the W element, and the substitution of some Mo by W can reduce the precipitation of Laves phase and TCP phase. W added within 4% will significantly improve the high temperature plasticity of the alloy.