【摘要】 用透射电子显微镜研究了改型与常规粉末７１８合金长期时效过程中γ″，γ′，δ相的析出、粗化行为．结果表明：改型合金与常规合金中γ″，γ′的析出行为不同，前者γ″和γ′主要以包覆及复合组织析出，后者γ″和γ′则多以单独、分离形式析出．在６５０℃等温１００００ｈ时效过程中，改型合金的γ″粗化速率低于常规合金，表现出良好的稳定性．经过７５０℃，１０００ｈ时效，两种合金均发生δ相的大量析出，但δ相在两个合金中析出的形貌、数量不同．更多还原

【Abstract】 The precipitation and coarsening behaviours of γ", γ’ and δ phases in powder manufactured modified 718 alloy with variation of chemical composition and heat treatment at 650 ℃ aging, up to 10000 h as well as 750℃, 1000 h, have been studied in comparison with that in conventional 718 alloy by TEM. Experimental results show that the precipitation behaviour of γ" and γ’ phase in the modified alloy is different from that in conventional one. In the former, γ" and γ’ phases precipitate in compact morphology and composite structure and in the later, γ" phase andγ’ phase precipitate independently. The coarsening rate of γ" phase in the modified alloy at 650 ℃ aging is slower than that in conventional one. The structure of modified alloy is more stable than coventional alloy. Large plates of δ phase precipitate in γ’ matrix of both alloys at 750℃, however the morphology and the amount of δ phases in two alloys are different.更多还原