First-principles calculation of structural stability of intermetallic compounds in Cu-Al layered composites
When copper-aluminum layered composites are formed by solid-liquid composite casting and rolling,the intermetallic compounds generated by the interface reaction between solid copper and liquid aluminum at the contact surface are prone to cause grain boundary brittleness,intergranular cracks,or elastic distortion,leading to cracking and failure of the composites.Therefore,a strong and stable interface is crucial for the structural strength of the entire composites.To gain a deeper understanding of the chemical bonding,crystal structure,and stability of intermetallic compounds at the interface,first-principles calculations were conducted on the thermodynamic properties,mechanical properties,and electronic structure of common intermetallic compounds(Al4Cu9,Al2Cu and AlCu)in Cu-Al layered composites.The calculated effective thermodynamic values indicate that the the Al2Cu phase will first form at the interface during the initial diffusion stage,and then Al4Cu9 and AlCu will be sequentially generated after the formation of the initial Al2Cu phase.Al2Cu,Al4Cu9 and AlCu all meet the criteria for mechanical stability.Comparing their B/G values,Poisson's ratio and hardness,all three intermetallic compounds are brittle phases,with Al2Cu having the highest brittleness and hardness.By analyzing the band structure,density of states and Mulliken population,it is found that metal bonds have stronger ionic characteristics in Al2Cu and AlCu chemical bonds,while they have stronger covalent characteristics in Al4Cu9 chemical bonds,resulting in a closer interaction between Al and Cu atoms and more stable.
Cu-Al layered compositesenthalpy of formationbinding energyelectronic structuremechanical property
NETL
NSTL
万方数据
