单晶高温合金气膜孔氧化损伤的薄壁效应研究

Thin-wall Effect of Oxidative Damage on Film Holes of Single Crystal Superalloy

通过静态增重法对不同孔间基体尺寸的DD6单晶高温合金在1050℃的恒温氧化行为进行测定,并利用扫描电镜、能谱以及X射线衍射等对氧化产物进行分析。结果表明:含气膜孔的DD6单晶高温合金发生氧化损伤薄壁效应的临界尺寸为0.75 mm。由于电液束加工属于一种电化学腐蚀加工方法,在孔边的电解腐蚀层已渗入基体,并导致靠近基体最内层的Al2O3膜不完全连续致密,进而保护性变差,从而在孔边形成一定范围的氧化高速反应区。随着孔间基体尺寸的增大,高速反应区面积逐渐增大到最大值后不再变化,此后生长应力的作用成为主导因素,而生长应力的叠加效应随着孔间基体尺寸的增大逐渐减小,因此峰值点之后又呈下降趋势。

The isothermal oxidation behavior of DD6 single crystal superalloys with different interpore matrix sizes at 1050℃was investigated by the static weight gain method.The oxidation products were analyzed by scanning electron microscope,energy spectrum and X-ray diffraction analysis.The results show that the critical size of oxidative damage and thin-wall effect of DD6 single crystal superalloy with gas film pores is 0.75 mm.The electrohydraulic beam machining adopted in this study is an electrochemical corrosion processing method,which makes the electrolytic corrosion layer at the edge of the hole penetrate into the substrate.Thus,the Al2O3 film near the innermost layer of the substrate is not completely continuous and dense,which causes the poor protection,and the formation a certain range of high-speed oxidation reaction zone.As the size of the inter-pore matrix increases,the area of the high-speed reaction zone gradually increases to the maximum value and then no longer changes.After that,the effect of growth stress becomes the dominant factor.Tche superposition effect of growth stress gradually decreases with the increase of the inter-pore matrix size,so it shows a downward trend after the peak point.