Ni/Al爆炸焊接界面形成的分子动力学模拟

Molecular dynamics simulation on interface formation in Ni/Al explosive welding

基于分子动力学,从微观角度仿真模拟Ni/Al结合界面的爆炸焊接过程,分析结合界面形成的加载、卸载和冷却阶段的形貌和微观结构。结果表明:Ni、Al板碰撞后动能转变为内能,异种金属间互相熔合渗透形成结合界面;冲击速度越大,卸载和冷却阶段扩散变化较明显;由于极高的应变速率和热效应,Ni板、Al板和混合区分别形成了胞状位错结构、多边形位错结构、典型凝固结构;爆炸焊接中FCC、BCC结构可逆向转变,加载时初始温度越高,FCC结构的逆向转化率越高,冲击速度为1 500、1 750、2 000 m/s时,分别提高了7.0%、15.6%、28.0%。

Based on molecular dynamics,the explosive welding process of Ni/Al bonding interface was simulated from the microscopic point of view. Based on the simulated results,the morphologies and microstructure of the interfaces during loading,unloading and cooling process were analyzed. The results show that the kinetic energy of Ni and Al plates is transformed into internal energy after collision,and the dissimilar metals are fused and infiltrated with each other to form the interface. The higher the impact velocity,the more obvious the variation of diffusion at unloading and cooling stages. Due to the extremely high strain rate and thermal effect,cellular dislocation structure,polygonal dislocation structure and typical solidification structure are formed in Ni plate,Al plate and mixed zone,respectively. The FCC structure and BCC structure can be mutually conversed in explosive welding. The higher the initial temperature during loading,the higher the conversion rate of FCC structure. When the impact velocity is 1 500 m/s,1 750 m/s and 2 000 m/s,the conversion rate of FCC structure into BCC structure increases by7.0%,15.6% and 28.0%,respectively.