Microstructure and Mechanical Properties of ZrC_x-NbC_y-Cu Composites by Reactive Infiltration at 1300 ℃

【摘要】 ZrC_x-NbC_y-Cu composites were fabricated by pressure-less reactive infiltration of Zr-Cu binary melts into porous NbC preforms at 1 300℃.The effect of Zr content in the infiltrator on microstructure of the as-synthesized composites was studied.Mechanical properties of the composites were reported.A partial displacement of Nb atoms in NbC by Zr atoms from Zr-Cu melt occurs during the reaction between Zr-Cu melt and porous NbC preform.The formation of a core-shell structure suggests the reaction is mainly a dissolutionprecipitation type.NbC dissolves into Zr-Cu melt,from which the （Nb,Zr）C_z phase precipitates and grows.With increasing Zr content in the Zr-Cu infiltrator,the reaction is enhanced and the infiltration is easily chocked.ZrC_x-NbC_y-Cu composite is synthesized using Zr₁₄Cu₅₁ infiltrator.The flexural strength and fracture toughness of ZrC_x-NbC_y-Cu composite reach 637 MPa and 12.7 MPa·m^1/2,respectively.And the improved toughness is probably attributed to residual Cu phase and plate-like Nb_xC_y phases.更多还原

【Abstract】 ZrC_x-NbC_y-Cu composites were fabricated by pressure-less reactive infiltration of Zr-Cu binary melts into porous NbC preforms at 1 300℃.The effect of Zr content in the infiltrator on microstructure of the as-synthesized composites was studied.Mechanical properties of the composites were reported.A partial displacement of Nb atoms in NbC by Zr atoms from Zr-Cu melt occurs during the reaction between Zr-Cu melt and porous NbC preform.The formation of a core-shell structure suggests the reaction is mainly a dissolutionprecipitation type.NbC dissolves into Zr-Cu melt,from which the （Nb,Zr）C_z phase precipitates and grows.With increasing Zr content in the Zr-Cu infiltrator,the reaction is enhanced and the infiltration is easily chocked.ZrC_x-NbC_y-Cu composite is synthesized using Zr₁₄Cu₅₁ infiltrator.The flexural strength and fracture toughness of ZrC_x-NbC_y-Cu composite reach 637 MPa and 12.7 MPa·m^1/2,respectively.And the improved toughness is probably attributed to residual Cu phase and plate-like Nb_xC_y phases.更多还原