Research On In-situ Particle Reinforced Copper-rich FeCoNiCu_x High Entropy Alloy Matrix Composites

In this paper,a copper-rich FeCoNiCu_x high-entropy alloy was prepared by vacuum induction melting method.FeCoNiCu_2.0 high-entropy alloy with optimal performance was selected as the matrix.In-situ Ti C and Ti B₂ particles were used to reinforced copper-rich matrix FeCoNiCu_2.0 high-entropy alloy,and the addition of trace alloy elements V and Nb on the basis of FeCoNiCu_2.0,and its effects on the microstructure and mechanical properties of the composite materials were researched.In addition,in this paper,the friction and wear properties of Ti C/FeCoNiCu_2.0 composites were studied.The microstructure analysis showed that there was a large amount of copper segregation in the intergranular region of FeCoNiCu_x high entropy alloys,for Ti C/FeCoNiCu_2.0 and Ti B₂/FeCoNiCu_2.0 composites,the different contents of reinforcements had a greater effect on the microstructure.When the volume fraction of the reinforcement was 10 vol%,the Ti C/FeCoNiCu_2.0 composite had the best microstructure;and the volume fraction of the reinforcement was 5 vol%,Ti B₂/FeCoNiCu_2.0 composites had the best microstructure,for Nb_xFeCoNiCu_2.0 and V_xFeCoNiCu_2.0 high entropy alloys,the microstructure was simple dendritic structure.The study of the reaction mechanism of the preform showed that in the Ti-C-Cu system,Cu₄Ti was formed in the first step,and the second step Cu₄Ti was decomposed,Ti atoms with C atoms combined to form Ti C.The apparent activation energy was 143.0 k J/mol and 279.0k J/mol.The precast Ti-B-Ni system consisted of three reaction steps,and Ti B₂ was formed.The apparent activation energy was 499.5 KJ/mol,1467.2 k J/mol,and 1678.5 k J/mol.The tensile mechanical properties research showed that FeCoNiCu_2.0 high entropy alloy had the best ultimate tensile strength of 473 MPa and elongation of 43.0%.The addition of a suitable amount of reinforcement and alloying element Nb can significantly increase the strength of the high entropy alloy.V element had less influence on material properties.The 10vol%Ti C/FeCoNiCu_2.0 composite material system had the best tensile properties,the ultimate tensile strength was 698 MPa,which was 47.6%higher than the matrix,the elongation was reduced to 25.6%,and the tensile fracture was a clear tough fracture feature.Friction and wear performance studies showed that the composite material had the best wear resistance when the volume fraction of the reinforcement was 10 vol%.The wear of composite materials with different reinforcement volume fractions(5 vol%,10 vol%)increased with increasing load and sliding speed,and the friction coefficient decreased with increasing load and sliding speed.There were two types of wear mechanisms:abrasive wear and adhesive wear.