对Al,Ta含量分别是6wt%Al,0wt%Ta;5wt%Al,4wt%Ta和6wt%Al,4wt%Ta三炉低Cr高W铸造镍基高温合金进行了静态空气下1100℃/2min～100h等温氧化试验,并对剥落氧化皮和合金试片表面氧化层进行X射线衍射分析,对氧化后的试片表面及横切面进行光学金相、定量金相、扫描电镜及能谱分析.结果表明:低Cr高W镍基高温合金的早期氧化主要表现为富难熔元素相MC,M6C碳化物和α(W,Mo)相的优先选择性氧化.6wt%Al,0wt%Ta合金和6wt%Al,4wt%Ta的合金经1100℃/100h氧化后的最终主要氧化产物均包含NiO,NiAl2O4和Ni-WO4,此外合金中还分别存在少量的NiNb2O6和Ni(Ta,Nb)2O6.合金的氧化动力学曲线遵循分段抛物线规律.Al量相同的情况下,Ta的加入通过增加共晶γ'量和减缓自由态硫对抗氧化的有害作用从而减少合金的氧化增重和延缓氧化皮剥落,提高合金的抗氧化能力.6wt%Al,0wt%Ta的合金与5wt%Al,4wt%Ta的合金具有相当的高温抗氧化能力,仅从高温抗氧化性能考虑,可以考虑以Al代Ta.
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