稀土Y对AISI430不锈钢抗高温氧化性能的影响

Effect of Rare Earth Y on High Temperature Oxidation Resistance of AISI430 Stainless Steel

通过离子注入的方式,在AISI430合金表面注入不同剂量的稀土Y对合金进行改性,研究了不同剂量的稀土Y对合金高温抗氧化性的影响。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱仪(XPS)分析氧化膜的物相构成、微观组织形貌、稀土Y的化学形态,并通过VL200DX超高温激光共聚焦显微镜对氧化过程进行原位观察。结果表明:合金表面注入稀土Y剂量为6×10^(17)ions/cm^(2)时具有最佳抗氧化性和抗剥落性,相比原始试样,单位面积增重量以及剥落量分别减少了43.7%,78.4%。合金表面注入Y优先氧化为Y_(2)O_(3),一方面促进氧化膜的形成,另一方面抑制了晶粒长大。此外,晶界处Y2O3阻碍了金属阳离子通过晶界向外扩散。重要地,部分Y3+取代了MnCr_(2)O_(4)尖晶石中Mn^(2+)、Cr^(3+)占位,产生空穴缺陷,缓解了氧化层内应力,减少裂纹和孔洞的产生,使氧化层与基体结合紧密。

Different doses of rare earth Y were implanted on the surface of AISI430 alloy by ion implantation and the effect of Y on the high temperature oxidation resistance of AISI430 alloy was investigated,.The characteristics of oxide scales were investigated by scanning electron microscopy(SEM),transmission electron microscope(TEM),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD).The oxidation process was observed in situ by VL200DX ultra high temperature confocal laser scanning microscope.The results s how that when the dose of rare earth Y implanted on the surface of the alloy is 6×10^(17)ions/cm^(2)the mass gain and the amount of spalling per unit area of Y-implanted samples reduce by 43.7%and 78.4%,respectively,compared with the un-implanted Y samples.Y ions on the alloy surface oxidize to Y_(2)O_(3) preferentially,which promotes the formation of oxide film and inhibits the grain growth.In addition,Y_(2)O_(3) at the grain boundary hinders the diffusion of metal cations through the grain boundary.Importantly,Y substitutes for Mn2+and Cr3+in MnCr_(2)O_(4)spine,resulting in the formation of vacancy defect.It relieves the internal stress of oxide layer and reduces the generation of cracks and holes,making oxide layer bond with the substrate closely.