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一种新型钛基钎料合金对γ-TiAl合金的钎焊性

Brazability of a novel Ti-based filler alloy on the γ-TiAl alloy

  • 摘要: 在钎焊温度范围为1050 ~ 1125 ℃下保温10 min,采用非晶Ti-Zr-Cu-Ni-Co-Mo钎料成功地实现了Ti-47Al-2Nb-2Cr-0.15B (原子分数,%)合金钎焊连接. 运用SEM,EDS,XRD,TEM和维氏硬度仪等分析研究了铸态和箔带钎料显微组织、温度(900 ~ 1125 ℃)和保温时间(0 ~ 15 min)对铸态钎料在TiAl基合金表面上润湿铺展面积的影响,以及钎焊接头中界面显微组织和维氏硬度在不同钎焊温度下的变化规律. 结果表明,随着温度和保温时间的增加,铸态钎料在TiAl合金母材表面润湿铺展面积的增幅先增大后减小. 钎焊接头界面组织主要包括TiAl母材层,α2-Ti3Al+AlCuTi (层Ⅰ)和γ-(Ti, Zr)2(Ni, Cu)+α-(Ti, Zr)(层Ⅱ). 钎缝中各区域的硬度均随着钎焊温度的增加而增加,1125 ℃时获得最大值为872(±8) HV,主要与钎缝中生成的硬脆金属间化合物(Ti, Zr)2(Ni, Cu)和α2-Ti3Al有关.

     

    Abstract: Ti-47Al-2Nb-2Cr-0.15B (at.%) alloy was successfully brazed at 1050 ~ 1125 ℃ for 10 min with amorphous Ti-Zr-Cu-Ni-Co-Mo filler. The microstructures of crystalline and amorphous fillers, the effects of brazing temperature (900 ~ 1125 ℃) and holding time (0 ~ 15 min) on the wettability and spreadability of the crystalline filler over the γ-TiAl alloy as well as the relationship between the microstructure and hardness of TiAl brazed joint at different brazing temperature were analyzed by SEM, EDS, XRD, TEM and Vickers hardness tester. Results showed that the increment of spreading area of the crystalline filler on γ-TiAl alloy increased firstly and then decreased with the increasing of temperature and holding time. The interfacial microstructure of γ-TiAl brazed joint mainly consisted of TiAl substrate layer, α2+AlCuTi (layer Ⅰ)and γ-(Ti, Zr)2(Ni, Cu)+α-(Ti, Zr) (layer Ⅱ). The hardness of the brazing seam increased with the brazing temperature and the maximum hardness of 872(±8) HV was obtained at 1125 ℃, which was mainly related to the hard and brittle (Ti, Zr)2(Ni, Cu) and α2-Ti3Al intermetallics generated in the brazing seam.

     

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