以高能球磨态90W-10(Ni-Cr-Fe-Si-B)(质量分数,%)混合粉末为钎料中间层,分别采用1000、1050和1100℃,均保温60 min并加压5 MPa的工艺参数,对纯钨(W)和0Cr13Al钢进行真空扩散钎焊连接.利用激光粒度分析仪、SEM、EDS和电子万能试验机等研究混合粉末形态、接头的微观组织、成分、力学性能及断口特征.结果表明:接头中的混合粉末中间层通过液相烧结过程,实现钨与钢的扩散钎焊连接,并在接头中生成均匀致密的钨基高密度合金层.高能球磨制备混合粉末对钨基高密度合金层压力下的均匀化与致密化生成具有关键作用.连接温度越高,钨基高密度合金层的液相烧结组织特征越明显.钨/钢接头剪切强度在125~130 MPa之间,断裂均发生在钨基高密度合金层/钨母材的结合区,断口主要呈现为钨母材的脆性沿晶断裂和钨基高密度合金层粘结相与钨颗粒相的韧性脱离断裂.
Vacuum diffusion brazing between tungsten (W) and 0Cr13Al steel using 90W-10(Ni-Cr-Fe-Si-B) (mass fraction, %) powder mixture interlayer prepared by high energy ball milling, was carried out with 5 MPa at 1000, 1050 and 1100 ℃ for 60 min, respectively. The morphology of powder mixture was studied by laser particle size analyzer and SEM. The microstructures, composition and fracture characteristics of the joints were studied by SEM, EDS and the shear strength of the joints were tested by electronic universal testing machine. The results show that the tungsten heavy alloy layer forms on the tungsten matrix through 90W-10(Ni-Cr-Fe-Si-B) mixed powder liquid phase sintering, and good bonding between tungsten and steel is realized based on diffusion brazing mechanism. High energy ball milling plays key role in densification and homogenization of tungsten heavy alloy layer. At higher bonding temperature, the liquid phase sintering microstructure characteristics of the tungsten heavy alloy layer is more obvious. The shear strength of joints is between 125-130 MPa. The fractures all occur near the interface of tungsten matrix and tungsten heavy alloy layer, the former fracture is brittle intergranular fracture, while the latter fracture is ductile interface debonding fracture between tungsten phase and Ni-rich phase.
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