CNTs对TC4与C/C复合材料钎焊接头组织及力学性能的影响

刘多; 李星仪; 赵可汗; 宋延宇; 钟素娟; 宋晓国

doi:10.12073/j.hjxb.20191106005

CNTs对TC4与C/C复合材料钎焊接头组织及力学性能的影响

Effect of CNTs on microstructure and mechanical properties of TC4 and C/C composites brazed joint

摘要

摘要: 试验采用加入了碳纳米管(carbon nanotubes，CNTs)的AgCu4.5Ti + xCNTs (x为质量分数，%)复合钎料(简称AgCuTi_C复合钎料)，实现了TC4钛合金与C/C复合材料的真空钎焊连接. 通过SEM，EDS等分析手段确定了在CNTs含量为0.2%、钎焊温度为880 ℃、保温时间为20 min时接头的典型界面组织为TC4/扩散层/Ti₂Cu/TiCu/Ti₃Cu₄/TiCu₄/TiC + TiCu₂ + Ag(s.s) + Cu(s.s)/Ti₃Cu₄/TiCu₄/TiC/C/C复合材料；研究了CNTs含量对接头组织与性能的影响. 结果表明，随着CNTs含量的增加，钎缝宽度变化呈下降趋势，界面组织细化，界面中的Ti₃Cu₄与TiCu₄脆性化合物的含量降低、TiC与TiCu₂化合物的含量增加；接头的抗剪强度呈先上升后下降的趋势变化；当CNTs含量为0.4%时抗剪强度最高，达到44 MPa；CNTs的加入可使界面组织得到细化，有利于缓解钎缝中心区域与两侧母材之间存在的由于热膨胀系数不匹配而形成的较大残余应力，有效地提高了接头的抗剪强度.

Abstract: TC4 titanium alloy was brazed to C/C composite by using AgCu4.5Ti+xCNTs (x represents weight content, %) composite filler with CNTs added (Herein after referred to as AgCuTiC composite filler) metal in vacuum. With the CNTs content was 0.2%, under the condition of 880 ℃/20 min, the typical interfacial microstructure of the brazed joint was TC4/diffusion layer/Ti₂Cu/TiCu/Ti₃Cu₄/TiCu₄/TiC+TiCu₂+Ag(s.s)+Cu(s.s)/Ti₃Cu₄/TiCu₄/TiC/C/C composites, which was determined by SEM and EDS. The effect of CNTs content on the microstructure and properties of the joint was investigated. The results indicated that with the increase of CNTs content, the width of the brazed joint decreased, the interfacial microstructure refined, the content of brittle Ti₃Cu₄ and TiCu₄ compounds in the interface decreased, the content of TiC and TiCu₂ compounds increased,the shear strength of the joint show a trend of increasing first and then decreasing. The maximal shear strength of 44 MPa was obtained with the CNTs content was 0.2%. With the addition of CNTs, the interfacial microstructure can be refined, the residual stress caused by mismatch of the thermal expansion coefficient between the central area of the joint and the substrate materials on both sides can be released, which improves the shear strength of the joint effectively.

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