First-Principles Study Of The Effects Of Rare Earths On The Atomic Configuration And Formation Mechanism Of WC_p/Iron Composite Interface

The interface of particles/reinforced metal composites plays an important role in transferring load,adjusting stress distribution and connecting the particle s and matrix.In the preparation process of particle s/reinforced metal composites,the formation of the interface is affected by the preparation technology,preparation parameters,wettability of the particles and the matrix,distribution morphology of particles and many other factors,resulting in the interface reaction is difficult to control,the interface structure is complex,and the interface phase components are numerous,small and dispersed.It has brought a lot of difficulties to the research,but the mechanism of the interfacial reaction of particle s/reinforced metal composite s is still not clear.At the same time,many literat ures have reported that adding rare earth to composites can effectively improve t he interfacial bonding strength,and improve the strength and toughness of the material.Due to the great activity of rare earth,they are usually adsorbed on the interface in the form of oxides or intermetallic compounds,which makes the interface structure more complex,and the experimental study on the interface properties of the rare earth modified composites more inconvenient.Therefore,tungsten carbide particles/reinforced iron composites as the research object,first principles calculation and combination of the experimental analysis and performance characterization method,constructed doping interface cell structure,and the interface electronic structure and thermodynamic properties were analyzed.To enrich the large database of the research on the interface of tungsten carbide particles/reinforced iron composites,to provide a theoretical basis for the research on improving the interfacial bonding strength of particles/reinforced iron composites,and to lay a foundation for the research on rare earth modified particle reinforced iron matrix composites.The main research contents and results of this paper are as follows:(1)the low exponential plane was taken as tangent of the two bodies,and the interface of Fe(110)/WC(0001)-c was established through structural optimization and interface mismatch calculation.The charge density analysis at the interface shows that there is a strong ionic bond between the Fe-C at the interface,and the covalent bond also ACTS,so that Fe(110)/WC(0001)-c has a strong bond strength and stable interface configuration.(2)the main components of interfacial phase of tungsten carbide p articles/reinforced iron composites include Fe ₃W₃C,Fe,WC,W₂C,W and a small amount of C.The generation of Fe₃W₃C helps to regulate the difference in thermophysiological properties between matrix Fe and WC,thus slowing down the generation of thermal crack at the junction of matrix Fe and reinforced particle.(3)the most likely reaction mechanism of Fe ₃W₃C is3Fe+2WC+W2C?Fe3W3C+2C+W.This prediction can provide reference for the research on the interface reaction of particles/reinforced iron composites reinforced by tungsten carbide particles.(4)when replacing W atom,the interface binding strength of doped Nd is the largest and the interface is the most stable;when replacing Fe atom,the interface binding strength of doped Ce is the largest and the most stable.When only the substitution doped interface is considered,Nd and Pr are more inclined to rep lace W atoms,while Y,La and Ce are more inclined to replace Fe atoms.(5)the doping of rare earth to strengthen the charge transfer between the Fe,W and C atom at the interface,not only makes the interface bonding ways changed,also the bonding between the atoms and strengthening,the final performance of rare earth doped tungsten carbide particles/reinforced iron composites interface bonding strength increased.(6)two of the six rare-earth Nd,Y,La,Ce,Pr and Pm were successfully selected.When adding rare-earth to tungsten carbide particles/reinforced iron composites to improve the interface performance,Nd or Ce can be selected in preferen ce to improve the interface performance.