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将静电场应用于GH4169合金的时效过程,研究了静电场对合金σ相沉淀析出行为的影响规律,并探讨了其机理.结果表明,合金在850℃以8 k V/cm静电场强度进行15 min时效,σ相开始在晶界析出;时效1 h晶内分布大量γ“相.随时效时间延长,σ相尺寸增大、体积分数增加,γ”相尺寸亦增大.与未加静电场时效处理相比,静电场时效处理后合金中σ相体积分数降低、尺寸减小,γ“相体积分数升高;晶界σ相中Nb原子分数降低、Fe和Cr原子分数升高,晶界σ相点阵常数c减小、a和b增大.由于静电场时效处理后合金中平均空位浓度升高,促进了Fe和Cr原子扩散,同时Fe和Cr原子置换晶界σ相中Nb原子,Nb原子固溶入晶内.另一方面,空位浓度的升高增加了γ”相非匀质形核几率,促进γ“相析出.同时,空位亦可松弛基体γ相与γ”相的共格畸变,有效抑制了γ“相向σ相转变,增加了强化相γ”相的稳定性.
The electrostatic field was applied to the aging process of GH4169 alloy and the influence law of electrostatic field on precipitation behavior of alloy σ phase was studied and its mechanism was also discussed.The results show that the alloy is annealed at 850 ℃ with 8 kV / cm electrostatic field intensity min, the σ phase begins to precipitate at the grain boundaries, and a large amount of γ “phase is distributed within 1 h of aging. With the aging time prolonging, the size of σ phase increases, the volume fraction increases, and the phase size increases. Compared with the aging treatment in the electrostatic field, the σ phase volume fraction decreased and the size of the γ ”phase increased after the aging treatment in the electrostatic field. The Nb atomic fraction in the σ phase in the grain boundary decreased and the fraction of Fe and Cr increased , The lattice constant σ of the sigma phase in the grain boundary decreases and a and b increase.The diffusion of Fe and Cr atoms is promoted due to the increase of the average vacancy concentration in the alloy after the aging of the electrostatic field and the substitution of the Fe and Cr atoms for the σ phase On the other hand, the increase of vacancy concentration increases the probability of heterogeneous nucleation of γ “phase and promotes the precipitation of [gamma] ” phase. Meanwhile, the vacancy may also relax the matrix γ phase The coherent aberration with γ "phase effectively inhibits the γ phase transformation and increases the stability of γ phase.