固溶强化型镍基合金的时效析出行为

Aging Precipitation Behavior of Solid-Solution Strengthened Nickel-Base Alloys

为了给700℃超超临界机组选材提供技术参考,研究了2种固溶强化型镍基合金(617和625)经时效处理(时效)后的析出行为。结果表明:2种镍基合金760℃时效后,均析出M23C6、M6C碳化物和γ′相;M23C6、M6C碳化物分布于晶界和晶内,γ′相分布于晶内;γ″相在625合金晶界、层错处析出并向晶内生长。617合金时效3 000 h,晶界析出相不连续分布;时效5 000 h后晶界析出相聚集且连续分布,晶内析出相的尺寸基本稳定。625合金时效3 000 h的晶内析出相尺寸无明显变化,晶界M23C6颗粒聚集长大;时效5 000 h后M23C6转变为M6C碳化物。617合金和625合金时效后的冲击吸收能量均明显下降,时效后的625合金脆化程度较时效后的617合金严重。

Aging preeipilation hehavior of the two solid-solution strengthened Ni-based alloys （617 and 625） Ires been invesligated. The resuhs revealed thal the M23C6, and M6C, carbide particles precipitated both at the grain boundaries anti inside grains, and the γ phase particles were situated at intragranular sites in the process of aging al 760 ℃ for two alloys. In addition, γ phase precipitated at grain houndaries arid stacking faults in the aged alloy 625. The carbide partieles discontinuously dispersed at grain boundaries after aging for up to 3 000 h for alloy 617： however, the 5 000 h aging induced the coalescence of the tar＇hide particles. After aging up to 5 000 h, the size of precipihltes inside grains remained basieally stable for alloy 617. The carbides preeipitates dispersed continuously al inter-granular site were observed in the alloy 625 aged for 3 000 h and an incre, ase of aging lime resulted in the growth of carbide partitcles. The size of inlragranular parlieles kept almost unchanged after aging for up to 3 000 h for alloy 625; however, the presence of a nnmher of M6C partieles was visible for alloy 625 after 5 000 h. The impact absorbed energy obviously declined for two alloys after aging. Aging cmhrilllement of the alloy 625 is grealer than that hi＇the alloy 617.