Strain-stiffening of chemical bonding enhance strength and fracture toughness of the interface of Fe2B/Fe in situ composite

Abstract

Fe2B was widely used as the strengthening phase and wear-resistant skeleton in high boron iron-based composite. The weak interfacial bonding of Fe2B/Fe interface is one of the main reasons for the poor mechanical properties of the composite, which motivated us to develop a strain stiffening strategy of interfacial chemical bonds to improve the bond strength and elongation of the interface. The effects of alloying elements Ti, Cr, Mn, Co, Ni, Cu, Y, Nb, Mo, Ta, and W on Fe(001)/Fe2B(001) interface were investigated through first-principles calculations. The interface segregation energy and the work of adhesion showed that Ti, Cr, Mn, Ni, Y, Mo, Ta, and W can segregate at this interface, and the alloying elements Cr, Mn, Ni, Nb, Mo, Ta and W increase the interface bonding strength. The fracture mechanism of the interface resulted from the breaking of the FeFe bond of the bcc-Fe end near the interface. The alloying elements Cr, Mn, and Ni improved the ultimate strength and elongation of bcc-Fe(001)/Fe2B(001) interface. CrB bond displays the obvious strain stiffening in the interface. Therefore, it provides new thought and method for the design of new high boron alloys.