Influence Of Rare-earth Element Doping On Interface And Mechanical Properties Of WC Particles Reinforced Steel Matrix Composites

The interfacial wettability,interfacial reaction mechanism and stability of metal matrix composites are the key work of domestic and foreign,which research workers have been studying for a long time.The main roles of the interface were found to be transferring load,regulating stress distribution,and preventing crack extension;and in metal matrix composites,rare earth elements can improve the wettability between the metal matrix and the reinforcement.Therefore,in this paper,WC particle-reinforced steel matrix composites doped with rare earth elements Y,La,Ce,and Nd were successfully prepared by means of powder metallurgical sintering process and interfacial remelting process.The effects of rare earth doping on the interfacial and mechanical properties of the composites under the conditions of sintering process and remelting process were analyzed by XRD,SEM,EDS,microhardness,nanoindentation,and compression experiments.As well as the calculation of mechanical properties such as bulk modulus(B),shear modulus(G),Young's modulus(E),and Poisson's ratio(?)of Fe₃W₃C by the first-nature principle of rare earth element doping.of Fe₃W₃C.The following conclusions were drawn from the analysis.The doping of rare earth elements Y,La,Ce,and Nd can accelerate the interdiffusion of Fe,C,and W elements in the composites.This leads to the early formation of the interfacial reaction zone of the composites as well as increases the width of the interfacial reaction zone.At different sintering temperatures and different remelting temperatures,the phase composition of the rare earth-doped composites was mainly?-Fe,W₂C,WC,Fe₃W₃C,and the rare earth doping did not induce the formation of new phases in the interfacial reaction zone.The Fe₃W₃C of the doped composites with rare earth Y and Nd increased with the increase of remelting temperature.The doping of rare earth elements Y,Ce,La,and Nd can reduce the bulk modulus,shear modulus,and Young's modulus of Fe₃W₃C.Also the doping of rare earth elements can increase the anisotropy of Fe₃W₃C,as well as the brittleness and hardness of Fe₃W₃C.According to the results of nanoindentation experiments,the hardness of the interfacial reaction phase of the composite increases and the Young's modulus decreases after doping with rare earths.The calculated results show the same trend as the experimental results.The rare earths decreased the hardness of the interfacial reaction zone of the doped composites,where the hardness of the matrix surrounding the interfacial reaction zone increased.The hardness difference between the interfacial reaction zone and the substrate.Under remelting process conditions,the microhardness of the interfacial reaction zone of the composites decreases and decreases with increasing remelting temperature after doping with rare earth elements Y and Nd elements.Under the sintering condition at 1350?,the compressive strength of the composites doped with rare earths increased from 296.7 MPa to 659.2 MPa.Under the sintering condition at 1450?,the compressive strength of the composites increased from 571 MPa to 858MPa;the compressibility of the composites doped with rare earths increased from 30%to 42.2%at the highest,and it can be seen that the composites doped with Y and Nd elements The compressive strength of the composites doped with Y and Nd elements is the best.Under the remelting process conditions,the doping of rare earth elements Y and Nd increased the compressive strength of the composites,and the composites had the best compressive strength under the remelting process conditions at 1340?.332,588 and 555 MPa,respectively.When the sintering temperature was increased from 1350?to 1450?,the crack generation and extension of the composites with different rare earth doping during compression was shifted from the bonding interface between the interfacial reaction zone and the matrix to the interfacial reaction zone.The compressive strength of the composites was increased,where the hardness difference between the interfacial reaction zone of the composites and the matrix was decreased,and the compressive strength of the composites was increased,then the interfacial bonding was better.Therefore,rare earth doping can increase the interfacial bonding strength of the composites.