Study On High-temperature Oxidation Behavior Of The Multielement Copper And Nickel Based Alloy

The multielement copper and nickel based alloy were prepared by vacuum melting in this paper, and the alloy homogenization processing. By means of metallographic microscope, XRD, SEM and microhardness meter for multiple structure of copper and nickel base alloy, hardness and high temperature oxidation behavior were studied. The results showed that Si element can significantly increase the hardness of copper and nickel alloy, but can’t improve the high temperature oxidation resistance of copper and nickel alloy, Cr, Al, Zr, the high temperature oxidation resistance of rare earth elements on alloy have varying degrees of increase.(1) Cu-Ni-Cr alloy as-cast organization by α-Cu phase and The β phase rich Cr, after annealing, the alloy microstructure refinement, part of the Cr by solid solution in the α-Cu phase. Cu-Ni-Cr alloy was prone to oxidation in the process of high temperature oxidation loss, their poor oxidation resistance.(2) Cu-Ni-Cr alloy, aluminum element is added to the Al content is 4wt.%, the microstructure of a small amount of Ni Al phase, Ni Al phase as the Al content increases with the increase in the number of. When Al content is 8wt.%, Ni Al phase is dissolved in the matrix after annealing, Al element to add the beta build small particles uniformly distributed in the matrix. When Al content is 12 wt.%, Ni Al phase at the grain boundary can be seen after annealing. Experimental results show that the alloy add 8wt.% Al element is more appropriate, Oxidation Al2O3 film forms on the surface of the alloy, but discontinuous Al2O3 membrane, the antioxidant properties of the alloy has a little increase.(3) Cu-Ni-Cr-Al alloy, silicon is added to the generated Ni2 Si phase in the alloy organization, with the increase of Si in the alloy elements, Ni Al phase gradually reduce. Ni2 Si strength is higher than the matrix phase, have the effect of the second phase strengthening, the significant increase in the hardness of alloy. But alloy oxidation experiments showed that Si element added to the Cu-Ni-Cr-Al alloy doesn’t improve the oxidation properties of alloy Al alloy.(4) Cu-Ni-Cr-Al alloy, zirconium is added to the alloy weaving Zr element in the main gathered at the grain boundary. Test the temperature is 700 ℃, the aluminum oxide mainly θ-Al2O3 metastable phase exist, such as partial theta phase transformation in the process of oxidation for α-Al2O3, volume shrinkage, oxide cracking and peeling. Test temperature is 800℃, the alloy continuous Al2O3 rapid formation on the surface of the oxide film, under the oxide film formed granular rich Cr oxide inside oxide layer. Test temperature is 850℃ when Al2O3 oxide film and Cr in the thickness of the oxide layer increases. 850℃ temperature oxide, which is beneficial to θ-Al2O3 metastable phase quickly into α-Al2O3 or Al, O atoms to generate α-Al2O3 directly.(5) Cu-Ni-Cr-Al-Zr alloy to add a small amount of rare earth element Ce, Ce and alloy elements in the form of high melting point compounds, the compounds with very small particles suspended in the melt, the oxidation hinder the diffusion of Cr, Al and other elements, in the alloy surface quickly form a thin layer of Cr2O3 oxide film, can’t completely prevent the diffusion of metal atoms and oxygen diffusion and Al in the alloy to the surface. Cr2O3 on the surface of the oxide film formed on a layer of Al2O3 oxide film. Cr2O3 oxide film and Al2O3 very thin oxide film and substrate combine closely, improve the adhesion performance of the oxide film and the substrate alloys and high temperature oxidation resistance.