电场处理对一种镍基变形高温合金晶间腐蚀性能的影响

Effect of Electric Field Treatment on Intercrystalline Corrosion of Nickel-Based Superalloy

对一种航空发动机隔热屏用镍基变形高温合金进行电场处理,研究了电场对合金组织及晶间腐蚀性能的影响。结果表明,经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820℃、4kV/cm条件下,电场处理10h后合金晶间腐蚀速率为65.26mm·a-1,与未经电场处理状态相比,降低幅度达25.25%。电场处理过程中合金晶内退火孪晶的产生、长大,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。

Electric field treatment was performed on one of nickel-based superalloy as heat shield used in aeroengine and the effects of electric field treatment on the microstructure and intercrystalline corrosion behavior were investigated. The results show that the intercrystalline corrosion resistance is improved by the electric field treatment and the intercrystalline corrosion rate decreases with the increasing treatment time. The intercrystalline corrosion rate is 65.26 mm.a1 when the alloy is treated by electric field under the condition of 820 ℃ and 4 kV/cm for 10 h, and the decreasing extent reaches 25.25 % compared with the alloy untreated. The formation and growth 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 increasing electric field treatment 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, which leads to the retardation of the corrosion ditches to go forward. The intercrystalline corrosion resistance of the superalloy is improved due to the improvement of corrosion behavior of the grain boundary.