Alloy Design and Development of INCONEL718 Type Alloy
The effect of the alloying elements Al, Ti, Nb, W and Co in INCONEL 718 type alloy on phase precipitation behavior has been investigated employing the Thermo-Calc software. The calculated results show that the solvus of γ phase could be raised with increasing the content of Al, which also increases the fraction of γ phase. When Al content is beyond 1.5％, σ phase begin to precipitate. Increase Ti content also can greatly increase γ solvus, however a certain amount of η phase can form when Ti content is greater than 1.0％. Increase of Al and Ti content both can remarkably decrease the fraction of δ phase. W addition promotes Laves phase formation.Microstructure at as-heat treated condition and after aging at 680℃ for 1000h of newly developed 718 type alloys with different contents of Al were studied via SEM, TEM, XRD and quantitative determination of precipitated phases by micro-chemical analyses. The results indicate that at as-heat treated condition, the fraction of g￠￠ and γ increases obviously while δ phase decreases with the increasing of Al content. The morphology of δ phase gradually evolves from needle-like into globular with the increase of Al content. After aging at 680℃ for 1000h, the separately precipitated g￠￠ and γ in conventional 718 alloy coarsen rapidly while the coarsening rate of associated precipitation of g￠￠ and γ in newly developed 718 type alloys with higher content of Al is much lower than that of the former.Based on thermodynamical and experimental results, the optimum content of Al, Ti and Nb of the developed 718 type alloy without W and Co additions has been obtained to be 1％, 1％ and 5.5％, respectively.
alloy design 718 type alloy Thermo-Calc γ′′ γ δ phase
Shuhong FU Jianxin DONG Maicang ZHANG Xishan XIE
High Temperature Materials Research Laboratories,University of Science and Technology Beijing, Beijing 100083, China
国际会议
郑州
英文
2007-10-23（万方平台首次上网日期，不代表论文的发表时间）