新型钴基与Nb-Si基高温合金扩散动力学研究进展
刘兴军, 魏振帮, 卢勇, 韩佳甲, 施荣沛, 王翠萍

Progress on the Diffusion Kinetics of Novel Co-based and Nb-Si-based Superalloys
LIU Xingjun, WEI Zhenbang, LU Yong, HAN Jiajia, SHI Rongpei, WANG Cuiping
表2 Nb-Si基高温合金中合金化元素的作用[29~36]
Table 2 Effects of alloying elements on Nb-Si-based superalloys[29-36]
ElementMicrostructure and mechanical propertyOxidation resistance property

Si

Alloy's strength increases, but its ductility and toughness decrease, due to the formation of Nb3Si and Nb5Si3

With increasing temperature over 1000oC, the resistance to oxidations decreases because of the reduction in the density of oxide films caused by a phase transformation in SiO2

Al

Inhibiting the formation of Nb3Si phase and promoting the formation of β-Nb5Si3. Toughness decreases, due to the formation of Nb3Al with a content of Al more than 6% (atomic fraction)

Resistance to the oxidation increases with formation of a dense layer of Al2O3

Cr

Inhibiting the formation of Nb3Si phase and promoting the formation of β-Nb5Si3. Formation of Nb9Si2Cr3 is be-neficial to creep resistance of the alloy, while the formation of NbCr2 phase has negative effectsEnhancing the oxidation resistance of the alloy above 1000oC by forming Nb9Si2Cr3, NbCr2 with high oxidation resistance and NbCrO4 which beneficial to improving adhesion of the oxide layer

Hf

Inhibiting the formation of Nb3Si phase and promoting the formation of β-Nb5Si3. High temperature creep properties decrease, due to the formation of Hf5Si3 intermetallic compound with a high content of Hf in alloysResistance to oxidations decreases because of embrittlement and cracking of the HfO2 layer with a high content of Hf

Ti

Stabilizing the Nb3Si phase. Toughness increases due to the increase in the diffusion rates of the atom and the growth of the phase Nbss caused by the addition of Ti

Enhancing the oxidation resistance of the alloy at a temperature below 800oC by forming dense TiO2 layers, and decreasing at a temperature above 800oC due to a phase transformation in TiO2

V

Stabilizing the α-Nb5Si3 phase and inducing the microstr-ucture transformation from dispersion to eutectic-like structure. Alloy's fracture toughness decreases, but its high temperature strength decrease, due to the softening of solid solution caused by thermal activation diffusion process

Resistance to oxidations decreases because of cracking of oxidation layers caused by the formation of V2O5 with a high content of V in alloys