Preparation And Properties Of Multi-Phase Synergetic Reinforced Cu Matrix Composite

Gd₂O₃ has excellent thermodynamic stability,arc suppression and ablative resistance,while Ti₃AlC₂ presents a hexagonal layered crystal structure and bridges the gap between metallic and ceramic properties,which make them potentially attractive as dispersive phases for Cu matrix composites towards high tensile strength and good ablation resistance.The in-situ particles are mainly distributed in Cu grains,which make them have a high interface bonding strength between the in-situ particles and Cu matrix,effectively enhancing the strength of Cu matrix composites.However,due to the limitation of in situ synthesized method,the content of in situ synthesized reinforcement phase is low,the performance of Cu matrix composite can be further improved by directly adding Gd₂O₃ or Ti₃AlC₂ particles.In this paper,Gd₂O₃/Cu composites were prepared by in-situ synthesized method,Gd₂O₃/Cu composites and Cu@Ti₃AlC₂-Gd₂O₃/Cu composites were prepared based on the in-situ Gd₂O₃/Cu composite by directly adding Gd₂O₃ or Ti₃AlC₂ particles.The parameters of internal oxidation process and sintering process for the preparation of Cu matrix composites were optimized.The effects of in-situ and ex-situ particles,electroless Cu plating on microstructure,mechanical properties,physical properties and ablation resistance of the Cu matrix composites were systematically studied.The strengthening mechanism of Cu matrix composite reinforced by multi-phase particles was also studied.The main results showed that the tensile strength and electrical conductivity of composites were affected by the the parameters of internal oxidation and sintering process through the number and size of the in-situ Gd₂O₃ particles.The optimal preparation process were internal oxidation 60 min at 925℃and hot pressing sintering 30 min at 900℃.Microstructure analysis found that the in-situ Gd₂O₃ particles were mainly distributed in the Cu grains,which strengthened the Cu matrix composites by grain-boundary strengthening,Orowan strengthening,thermal mismatch strengthening and load transfer strengthening mechanisms.The ex-situ Gd₂O₃ or Ti₃AlC₂ particles were mainly distributed at the Cu grain boundaries,which strengthened the Cu matrix composites mainly by thermal mismatch strengthening and load transfer strengthening.The synergistic effect of the in-situ Gd₂O₃ and ex-situ Gd₂O₃ or Ti₃AlC₂ particles could effectively strengthen the Cu matrix composites.The properties of the Cu@Ti₃AlC₂-Gd₂O₃/Cu composites were further improved due to the electroless Cu plating on the surface of the Ti₃AlC₂ particles,which improved the interfacial bonding between Cu@Ti₃AlC₂ and Cu matrix.The in-situ Gd₂O₃ particles had a better strengthening effect on the properties of the Cu matrix composites than ex-situ Gd₂O₃ or Ti₃AlC₂ particles under the same condition.The tensile strength of Gd₂O₃/Cu composites prepared by in-situ synthesis method improved with the increase content of the in-situ Gd₂O₃ particles,when the content of in-situ Gd₂O₃ was 2.0wt%,the tensile strength of the Gd₂O₃/Cu composite reached to the highest value of 325.4 MPa.When the content of ex-situ Gd₂O₃ or Ti₃AlC₂ was 1.5 wt%,the tensile strength of the Gd₂O₃/Cu and Cu@Ti₃AlC₂-Gd₂O₃/Cu composites reached to the highest values of 360.9 MPa and 378.9MPa,which were improved by 54.0%and 61.8%comparing with the pure Cu prepared under the same conditions.The ablation resistance of Cu matrix composites was improved by the in-situ Gd₂O₃ particles and ex-situ Gd₂O₃or Ti₃AlC₂ particles.The Severity of ablation gradually reduced in the order of pure Cu,Gd₂O₃/Cu composite prepared by in-situ synthesized method,Gd₂O₃/Cu composite and Cu@Ti₃AlC₂-Gd₂O₃/Cu prepared by the combination method of in-situ synthesis and directly adding under the same condition by comparing the The mass loss,ablation area and depth.Based on the result of preparation,microstructure and properties of Cu matrix composites,the combination method of in-situ synthesized Gd₂O₃ and adding Ti₃AlC₂ or Gd₂O₃ was proposed,the mechanical properties and ablative resistance of Cu matrix composites were improved effectively through the synergistic strengthening effect of various reinforcement phases.