GH4169合金热腐蚀组织的演化行为

Evolution Behavior of Hot Corrosion Microstructure of GH4169 Alloy

镍基高温合金的零部件服役过程存在热腐蚀现象,易加速服役工件失效,缩短服役寿命。文章采用表面涂盐方法,研究GH4169合金I型(850℃)及Ⅱ型(650℃)的高温热腐蚀时序演化行为,发现合金表面及截面的腐蚀程度整体随时间延长而加剧。低温下合金截面处内外腐蚀层之间可观察到一层连续Al_(2)O_(3)带,该氧化物带对腐蚀有阻碍效果,而高温下合金的氧化层剥落及腐蚀孔洞现象更严重,Al_(2)O_(3)呈点状分布,且I型腐蚀更严重。此外,在合金腐蚀表面检测到Cr_(2)O_(3)、Fe_(2)O_(3)、Fe_(3)O_(4)和NiCr_(2)O_(4)等物质,Ni、Al、Cr、Fe与O、S、Cl的吉布斯自由能计算结果与实验观察一致。

High temperature corrosion phenomena can be detected in Ni-based superalloy components,which can result into the failure of work pieces and shorten the service life.By adopting the method of surface coated salt,this paper studies the temporal evolution behavior of high temperature thermal corrosion of GH4169 alloy type I(850℃)and type II(650℃),and it is found that the corrosion degree of the alloy surface and cross-section as a whole increases with the extension of time.A continuous Al_(2)O_(3)band can be observed between the inner and outer corrosion layers at the cross-section of the alloy at low temperatures,and the oxide band has a hindering effect on the corrosion,whereas the oxide layer spalling and corrosion holes of the alloy are more serious at high temperatures,and Al_(2)O_(3)is distributed in pitting form,and the corrosion of type I is more serious.In addition,Cr_(2)O_(3),Fe_(2)O_(3),Fe_(3)O_(4),and NiCr_(2)O_(4)are detected on the corroded surfaces of the alloys,and the Gibbs free energy calculations of Ni,Al,Cr,and Fe with respect to O,S,and Cl are in agreement with the experimental observations.