91W-6Ni-3Fe难熔合金、TiAl合金和铁基合金在熔铝中的耐腐蚀行为(英文)

采用静态浸没腐蚀试验研究91W-6Ni-3Fe难熔合金(91W)、TiAl金属间化合物和两种常用铁基合金(QT700和H13 钢)在750℃铝液当中的腐蚀性能。通过3D光学显微镜、SEM、EDS 和XRD研究样品的表面形貌,腐蚀界面和相组成。结果表明:91W具有最好的耐铝液腐蚀性能,QT700次之,H13再次之,TiAl合金的耐铝液腐蚀性能最差。四种金属材料的腐蚀失重均符合抛物线规律,材料在经过一开始的加速腐蚀阶段后,腐蚀速率趋于稳定。材料在铝液当中溶解遵循扩散-反应机制,91W材料在铝液当中的腐蚀主要由扩散这一速控步骤所决定,而TiAl合金的腐蚀性能差主要是由于TiAl-(TiAl3)-Al扩散偶反应具有较低的激活能。

Corrosion resistance of 91W-6Ni-3Fe refractory metal,TiAl compound and iron based alloys in molten aluminum

The corrosion behaviors of 91W-6Ni-3Fe (91W) refractory alloy, TiAl intermetallic compound and two types of iron based alloys (QT700 and H13 tool steel) in a liquid aluminum were investigated. Corrosion experiments or static immersion-tests were carried out in pure molten aluminum at 750 ℃. The surface micro-topographies, corrosion interfaces and phase compositions of the immersed samples were investigated by 3D optical microscopy, SEM, EDS and XRD. The results show that 91W exhibits the best corrosion resistance, followed by QT700, H13 and TiAl alloy, consequently. The corrosion mass loss of the four metallic materials adheres to parabolic criterion, and the corrosion rate trends to be stable after initial acceleration. The diffusion-reaction mechanism is proposed for the dissolution of materials in molten aluminum, and the diffusion process is the rate-determining step during the dissolution of 91W in molten aluminum, while the low activation energy for the reaction between TiAl-(TiAl3)-Al couple results in poor corrosion resistance of TiAl alloy in molten aluminum.