Adhesion properties and damage tolerance of W-Fe graded interfaces from first-principles calculation

Transitional multilayers with a gradient change of compositions and structures have been developed for the bonding between tungsten and steel in the experiments, however, very few works have focused on the design of the layer amount and composition. In this work, the influences of layer amount and composition on adhesion strength, interface stability, fracture toughness, and damage tolerance of W-rich and Fe-rich W-Fe bilayers were thoroughly examined using a combination of first-principles calculations and thermodynamic modeling. It is found that keeping more graded layers of W-rich region can maintain interface adhesion and improve damage tolerance, and the specific bilayers of Fe₅W₃//Fe₆W₂ and Fe₆W₂//Fe₈ should be chiefly considered in the design of Fe-rich region. The derived results are in good agreement with the experimental observations, and provide a deep mechanistic understanding of the performances of the graded multilayers proposed in the present work.