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本文报导了采用自行设计的液态锂静态腐蚀试验装置,对常用的5种高温合金(GH-30、GH-128、GH-37、GH-49和K-38)在800°、850°和900°进行了20小时对比筛选试验。用失重和晶界渗透深度来评价其抗蚀性;用扫描电镜(SEM)观察表面腐蚀形貌,并以能量色散谱仪(EDS)分析相成份;用电子探针(EMPA)和离子探针(IMA)鉴别晶界渗透腐蚀产物,结果表明;试验合金的腐蚀失重都随温度升高而增加;GH-49和K-38失重较小,GH-30失重较大。γ′相强化的合金(GH-37、GH-49和K-38)发生锂沿晶界渗透,并随温度升高而加深。固溶强化合金的腐蚀特征是镍的择优离析和Kirkendall效应,使基体产生空穴,最后形成α-Cr(Mo,w)骨架状多孔松散层。由γ+γ′两相组成的γ′相强化合金,晶界主要足由碳化物的γ′包膜组成,由于锂沿晶界渗透形成Li_2C_2等化合物,并发生γ′包膜的择优离析,使Li_2C_2两侧形成腐蚀深沟,这种包围着晶粒的深沟被打通后将使整个晶粒脱落,这是造成γ′相强化合金失重的主要原因。
This paper reports the use of a self-designed liquid lithium static corrosion test apparatus for measuring the corrosion resistance of five popular superalloys (GH-30, GH-128, GH-37, GH-49 and K-38) at 800 °, 850 ° and 900 ° ° A 20-hour comparative screening test was performed. The corrosion resistance was evaluated by weight loss and grain boundary penetration depth. The surface morphology was observed by scanning electron microscopy (SEM) and the phase composition was analyzed by energy dispersive spectroscopy (EDS). The electron probe (EMPA) and ion probe (IMA). The results show that the corrosion loss of the alloy increases with the increase of temperature. The weight loss of GH-49 and K-38 is smaller and the weight loss of GH-30 is larger. The γ ’phase strengthened alloys (GH-37, GH-49 and K-38) undergo lithium penetration along the grain boundaries and deepen with increasing temperature. The corrosion characteristics of the solid solution strengthened alloy are the preferential separation of nickel and the Kirkendall effect, resulting in cavitation in the matrix and finally the formation of a-Cr (Mo, W) framework-like porous loose layer. Γ ’phase alloy consisting of two phases of γ + γ’. The grain boundary mainly consists of the γ ’envelope of carbide. Due to the infiltration of lithium along the grain boundary to form compounds such as Li_2C_2 and the preferential separation of γ’ So that the formation of deep corrosion on both sides of Li_2C_2 ditch, this surrounded by the deep groove will be opened up after the entire grain off, which is caused by γ ’phase reinforcement of the main causes of weight loss.