(中南大学 轻质高强结构材料国家级重点实验室，长沙410083)
摘 要: 复合阻隔扩散连接技术是制备高性能钨/钢异种金属结构件的有效方法。本文研究Ti/Ni复合中间层扩散连接钨与钢接头的断裂行为，分析金属间化合物和残余应力对钨/钢接头性能及断裂方式的影响。结果表明：在拉伸载荷作用下，钨/Ti/Ni/钢扩散连接接头呈现出界面断裂、反应层断裂和混合断裂等3种断裂模式；在较低的连接温度和较短的保温时间下，钨/钢接头发生W/Ti界面断裂，接头强度较低；随着连接温度升高，钨/钢接头断裂发生在钨基体和W/Ti界面的混合区域，接头强度在(950℃, 1h)时达到最高，受残余应力和界面强度共同控制；随着连接温度进一步升高，Ti/Ni界面硬脆金属间化合物Ti2Ni、TiNi和TiNi3不断长大，厚度过大造成钨/钢接头在Ti–Ni金属间化合物层断裂。最后，分析钨/钢接头发生解理断裂的微观机制。
关键字: 断裂；扩散连接；钨；复合中间层；残余应力
（National Key Laboratory of Science and Technology for National Defence on High-strength Structural Materials, Central South University, Changsha 410083, China）
Abstract:Composite isolation diffusion bonding technology is an effective method to fabricate high performance tungsten/steel dissimilar metal structural parts. In this paper, the joint fracture characterization of Ti/Ni composite interlayer diffused W-steel was studied, and the influences of intermetallic compounds and residual stresses on the properties and fracture modes of W-steel joints were analyzed. The results show that the W/Ti/Ni/steel diffusion joint presents three fracture modes under tensile load: interfacial fracture, reaction layer fracture and mixed fracture. Under low bonding temperature and short holding time, the main failure mode of W/steel joint is interface fracture, as the connection temperature increases, the fracture of the tungsten/steel joint occurs in the mixed area between the tungsten matrix and the W/Ti interface. The joint strength reaches its maximum at (950 ℃, 1 h), and is controlled by the residual stress and the interface strength. However, with the further increase of the connection temperature, the Ti/Ni interface hard and brittle intermetallic compounds Ti2Ni, TiNi and TiNi3 continue to grow, and the excessive thickness causes the tungsten/steel joint to break in the Ti/Ni intermetallic compound layer. Finally, the micro mechanism of cleavage fracture of W/steel joint is revealed.
Key words: fracture; diffusion bonding; tungsten; composite interlayer; residual stress
