Strain-induced Precipitation Behavior of 8 Phase in Inconel 718 Alloy

• Published in: 钢铁研究学报：英文版 Vol. 21; no. 3; pp. 375 - 381
• Main Author: Xian-ping WEI Wen-jie ZHENG Zhi-gang SONG Ting LEI Qi-long YONG Qing-cheng XIE
• Format: Journal Article
• Language: English
• Published: 2014
• Subjects: 718合金; PTT曲线; 动力学曲线; 应变诱导; 析出行为; 能量色散谱; 透射电子显微镜; 镍铁合金
• ISSN: 1006-706X; 2210-3988

To study the precipitation dynamics of 3 phase in Inconel 718 alloy, two-stage interrupted compression method was used in the region of cold deformation temperatures and the temperatures range from 875 to 975 ℃. The precipitation-time-temperature （PTT） curve of 3 phase was obtained by analyzing the softening kinetics curves. For verifying the type of the precipitates and confirming the validity of the test, the transmission electron microscopy （TEM）, scanning transmission electron microscopy （STEM） and energy dispersion spectrum （EDS） were em- ployed. Experimental results indicated that the PTT curve for 3 precipitation exhibited a typical ＂C＂ shape and the nose points of start and finish precipitation were about 5 s at 920 ℃ and 2 815 s at 940 ℃, respectively. In addition, the nucleation of δ was heterogeneous. The nucleation sites varied with temperatures, including dislocation, grain boundary and stacking fault within γ″ phase. And 3 particles grew quickly at higher temperature with lower density. Moreover, the driving force of nucleation was mainly including chemical free energy, interracial energy and disloca- tion distorted energy. And the dislocation distorted energy could decide the density of nucleation in the strain-induced process.