Abstract
The high-temperature oxidation behavior of novel Co-Cr-Nb-W carbide-strengthened wear-resistance alloys with different Al contents(1wt％,2wt％and 3wt％)at 950,1000 and 1050 ℃ was thoroughly investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy and field emission electron probe analyzer.The porous property of NbC in-situ oxi-dation products(Nb2O5,CoNb2O6 and Co4Nb2O9)induces a multi-layered oxide scale with micropores and cracks.Co-Cr-Nb-W alloy with 1 wt％Al undergoes catastrophic oxidation and spalling above 1000 ℃.The outward transportation of Cr and Co is effectively restrained by a continuous Al2O3 scale formed around NbC in-situ oxi-dation region when Al content reaches 3 wt％.The β-CoAl in Co-Cr-Nb-W alloy with 3 wt％Al has an oxidation priority over eutectic carbides and the alloy matrix which are both enriched with Cr,thereby preventing the formation of Cr-depletion area and improving the self-healing ability of the oxide film.A slight change in Al content has a remarkable influence on the cooperative effect of Al and Cr and multiplies the antioxidant capacity of Co-Cr-Nb-W alloy above 1000 ℃.
基金项目
National Key R&D Program of China(2022YFC3902002)
NETL
NSTL
万方数据