新型718合金的元素强化作用及组织稳定性研究

Investigation on Strengthening Effect of Elements and Structure Stability of Novel Developed 718 Alloys

通过对718合金中沉淀强化元素Al,Ti以及固溶强化元素W含量的调整,研究了δ相形成规律及合金中γ′′/γ′复合析出组织的形成条件,同时分析了合金的微观组织与力学性能之间的关系。结果表明,维持理想的(Al+Ti+Nb)含量(at%)及(Al+Ti)/Nb原子分数比可以显著减少针状δ相的析出,得到稳定的γ′′/γ′复合析出组织并提高合金的拉伸强度、持久及硬度等多项力学性能。而在718合金基础上,采用W强化的合金与原型718合金相比也显现出了更为优异的力学性能。

The precipitation behavior of δ phase, γ″and γ′ phase was studied through adjusting precipitated strengthening elements Al, Ti and solution strengthening element W in 718 alloy. The relationship between microstructure and mechanical properties were also investigated. Experimental results indicate that maintaining of optimum level of （Al＋Ti＋Nb）at% and （AI＋Ti）/Nb atomic ratio in 718 alloy is benificial to the formation of γ″/γ′ compact precipitation, obviously restrains the trend of long needle-like δ precipitation and improves mechanical properties such as high temperature tensile strength, stress rupture life and hardness. In addition, the alloy based on conventional 718 alloy strengthening by addition of W element shows much better mechanical properties than that of conventional 718 alloy.