一种单晶高温合金的高温抗氧化性能研究

Study on Oxidation Resistance of a Single Crystal Superalloy at High Temperature

在高温度梯度真空定向凝固炉中,采用螺旋选晶法制备了一种单晶高温合金试样,分别在1 050℃、1 100℃和1 140℃研究了合金抗氧化性能,采用扫描电镜、X射线衍射仪、能谱分析仪对氧化物进行了分析。结果表明,合金具有优异的高温抗氧化性能,不同温度的氧化动力学曲线基本遵循抛物线规律。合金1 050℃和1 100℃的氧化膜保持完好,1 140℃氧化膜少量剥落。合金不同温度的氧化产物基本相同,氧化膜分三层,外层为不规则球形Ni O,中间为混合氧化物,内层由深色的Al2O3组成。氧化物下面都形成了无γ′相和γ′相减少的区域。

A single crystal superalloy was cast by screw selecting method in the directionally solidified furnace. The oxidation resistance of the alloy at 1050 ℃, 1100 ℃ and 1 140 ℃ was studied. Morphology of oxidation layer was examined by SEM and their composition was analyzed by XRD and EDS. The results show that the alloy has excellent oxidation resistance and basically obeys parabolic rate law during oxidation of 100 h at different temperature. No spallation of the scale was observed on the surface after oxidation at 1050 ℃ and 1 100 ℃, while a little spallation was found on the oxide scale after oxidation at 1140 ℃. The oxidation products of the alloy at different temperature are basically same. The oxide scale is made up of an outer NiO layer, an intermediate layer composed of oxide mixture, inner Al2O3 layer. The γ＇-free layer and γ＇-reduce layer were formed under the oxide scale.