电场处理对GH3044合金腐蚀行为的影响

EFFECTS OF ELECTRIC FIELD TREATMENT ON CORROSION BEHAVIOR OF GH3044 SUPERALLOY

将电场处理技术应用于镍基变形高温合金GH3044,研究了电场对合金组织及腐蚀行为的影响。结果表明,电场处理后合金耐晶间腐蚀能力得到提高,随电场处理时间的延长腐蚀速率减小。在800℃、6.4kV/cm条件下,电场处理10 h后合金腐蚀速率为2.06 mm/a,与未经电场处理状态相比,降低幅度达37.33%。电场处理过程中合金晶内大量退火孪晶的产生,使原始大角度晶界与退火孪晶相交处原子重新排列,随电场处理时间的延长,大量的原始大角度晶界被取代,呈连续分布的合金元素贫化网络被隔断,导致腐蚀沟前进受到阻碍,从而改善合金晶界的腐蚀行为,提高合金耐晶间腐蚀能力。同时,电场处理促进合金中原子扩散,使普通大角度晶界两侧Cr、Mo等合金元素的贫化趋势降低,也是合金耐腐蚀性能得以改善的重要原因。

Electric field treatment was performed on one of nickel-base superalloy GH3044 and the effects of electric field treatment on the microstructure and corrosion behavior of the alloy were investigated.The results show that the intergranular corrosion resistance of the alloy is improved by the electric field treatment and the intergranular corrosion rate decreases with the increasing treatment time.The intergranular corrosion rate is 2.06 mm/a when the alloy is electric field treated under the condition of 800℃and 6.4 kV/cm for 10 h,and the decreasing extent reaches 37.33%compared with the alloy untreated.The formation of the annealing twins during the electric field treatment cause the redistribution of atoms of the crossings between the original high angle grain boundaries and the annealing twins.With the increase of electric field treated time,a large amount of original high angle grain boundaries are replaced and the continuous distribution of depletion network of the alloying element is separated,those lead to the retardation of the corrosion ditches to go forward.The intergranular corrosion resistance of the superalloy is improved due to the improving of intergranular corrosion behavior of the grain boundaries.Moreover,the promotion effect of electric field treatment on atom diffusion rate decrease the exhaustion tendency of Cr and Mo elements on both sides of normal high angle grain boundary. Those can be considered as the reasons of improving the corrosion resistance after electric field treatment.