摘要
TiAl alloy and 316L stainless steel were vacuum-brazed with Zr−50.0Cu−7.1Ni−7.1Al(at.%)amorphous filler metal.The influence of brazing time and temperature on the interfacial microstructure and shear strength of the resultant joints was investigated.The brazed seam consisted of three layers,including two diffusion layers and one residual filler metal layer.The typical microstructure of brazed TiAl alloy/316L stainless steel joint was TiAl alloy substrate/α2-(Ti3Al)/AlCuTi/residual filler metal/Cu9Zr11+Fe23Zr6/Laves-Fe2Zr/α-(Fe,Cr)/316L stainless steel substrate.Discontinuous brittle Fe2Zr layer formed near the interface between the residual filler metal layer andα-(Fe,Cr)layer.The maximum shear strength of brazed joints reached 129 MPa when brazed at 1020℃ for 10 min.The diffusion activation energies ofα2-(Ti3Al)andα-(Fe,Cr)phases were−195.769 and−112.420 kJ/mol,respectively,the diffusion constants for these two phases were 3.639×10^(−6) and 7.502×10^(−10)μm^(2)/s,respectively.Cracks initiated at Fe2Zr layer and propagated into the residual filler metal layer during the shear test.The Laves-Fe2Zr phase existing on the fracture surface suggested the brittle fracture mode of the brazed joints.
采用Zr−50.0Cu−7.1Ni−7.1Al(摩尔分数,%)非晶钎料钎焊TiAl合金/316L不锈钢,并针对钎焊时间和温度对接头界面显微组织与剪切强度的影响进行研究。钎缝由两个扩散层和一个中间的残留钎料层组成。TiAl合金/316L不锈钢钎焊接头的典型结构为:TiAl合金母材/α2-(Ti3Al)/AlCuTi/残留钎料层/Cu9Zr11+Fe23Zr6/Laves-Fe2Zr/α-(Fe,Cr)/316L不锈钢母材,在残留钎料层和α-(Fe,Cr)层之间存在不连续的脆性Fe2Zr Laves相。钎焊参数为1020℃、10 min时接头剪切强度达到最大值129 MPa。α2-(Ti3Al)相和α-(Fe,Cr)相的生长激活能分别为−195.769和−112.420 kJ/mol,其扩散常数分别为3.639×10^(−6)和7.502×10^(−10)μm^(2)/s。断口分析结果显示,裂纹在Fe2Zr层中萌生,然后向残留钎料层扩展,断口呈现脆性断裂特征且在断口表面检测到Fe2Zr Laves相。
基金
financially supported by the National Natural Science Foundation of China(No.51674060)
Collaborative Innovation Center of Major Machine Manufacturing in Liaoning province,China。
