Preparation Of Cu-based In-situ Composites By Mechanical Alloying And Spark Plasma Sintering

Cu based composites are widely used in electric, automotive and aerospace industrialfield due to their excellent comprehensive properties, e.g., high electric conductivity, highthermal conductivity, high strength, etc. The in-situ method as a new technology hasattracted universal attention of the domestic and foreign scholars.In this paper, the combination of Mechanical Alloying with Spark Plasma Sinteringwas applied to prepare Cu based composites reinforced by Al₂O₃particles and Cu-Alintermetallic compound, respectively. The influences of key parameters of MechanicalAlloying on the structure, properties and process of Spark Plasma Sintering wereinvestigated. The microstructure of the composites and reaction mechanism was alsostudied.The results show that the in-situ reaction between CuO and Al can occur obviously inMechanical Alloying in CuO-Al reaction system. The addition of60wt.%copper asdilution effectively controlled the severe combustion reaction during Spark PlasmaSintering. But the final Al₂O₃particles are coarse and inhomogeneous because ofrestriction of milling time.The Cu/Al₂O₃composite powder is obtained by two-step ball-milling which couldeffectively control the self-propagating combustion reaction. The Cu base bulk compositereinforced by150nm Al₂O₃particulates is fabricated by spark plasma sintering. Themicrohardness of the bulk is220HV.In the process of preparation of the Cu based composite reinforced by the Cu-Alintermetallic compound, partial Al atoms diffuse into the Cu lattice which leads to theformation of Cu（Al） solid solution by Mechanical Alloying in the Cu-Al reaction system.And the residual fine Al particles are distributed in Cu phase. During Spark PlasmaSintering, part of the residual Al is continuing to dissolve into Cu lattice and the otherresponds with Cu into an metastable phase AlCu₃. After fast cooling, the Cu basedcomposite reinforced by in-situ AlCu₃particles is fabricated. The microhardness of thebulk is230HV.