B4C陶瓷/1060 Al钎焊界面行为和力学性能研究

Investigation of the interfacial behavior and mechanical properties of B4C/1060 Al brazed joints

  • 摘要: 采用Al-Si-Mg-Bi活性钎料实现多层B4C/1060Al/B4C的钎焊连接。系统研究了钎焊温度和保温时间对钎焊接头组织及剪切强度的影响。确定最优钎焊工艺为650 ℃×20 min,此时接头的剪切强度为63 MPa,接头相组成为B4C/α-Al+Al2Si+AlB2+Al4C3/Al。随钎焊温度的升高与保温时间的延长,钎焊接头的剪切强度均呈现先升高后降低的变化规律,且所有工艺参数下的接头均表现为脆性断裂特征。其中,610 ℃×20 min工艺条件下,断裂失效发生于B4C陶瓷与钎料层的界面结合处;在650 ℃×20 min工艺参数下,断裂位置转移至1060Al与钎料层的界面;当钎焊温度过高或保温时间过长时,界面区域会过量生成脆性相Al4C3,同时伴随内应力的显著累积,最终造成钎焊接头的力学性能劣化。

     

    Abstract: The brazing connection of multi-layer B4C/1060Al/B4C was achieved by using Al-Si-Mg-Bi active brazing filler metal. The effects of brazing temperature and holding time on the microstructure and shear strength of brazed joints were systematically studied. The optimal brazing process was determined as 650 ℃×20 min. At this time, the shear strength of the joint was 63 MPa, and the phase composition of the joint was B4C/α-Al+Al2Si+AlB2+Al4C3/Al. With the increase of brazing temperature and the extension of holding time, the shear strength of the brazed joint first increases and then decreases, and all joints under different process parameters exhibit brittle fracture characteristics. Specifically, under the process of 610 ℃×20 min, fracture failure occurs at the interface between B4C ceramic and the brazing filler metal layer, while under 650 ℃×20 min, the fracture position shifts to the interface between 1060Al and the brazing filler metal layer. It is concluded that excessively high brazing temperature or overly long holding time leads to excessive generation of brittle phase Al4C3 in the interfacial region, accompanied by significant accumulation of internal stress, which ultimately causes the deterioration of the mechanical properties of the brazed joint.

     

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