Study On Y₂O₃ Dispersion-reinforced Cu-based Composites

The oxide dispersion-strengthened(ODS)copper-based composites have excellent conductivity and mechanical properties.And oxide particles with high-melting point are dispersed in the copper matrix as the strengthening phase,which makes the alloy have better thermal stability and be widely used in lead frame,electrical contact material and contact line material.Different from the traditional reinforced phase like Al2O3,the tombarthite oxide with fluorite structure is added to the Cu matrix as the strengthened phase,which can form a coherent phase interface with the matrix to obtain the precipitation strengthening effect.In this paper,Y2O3 particles dispersed-strengthened copper matrix composites were prepared by solid phase in-situ reaction,liquid phase in-situ reaction and spark plasma sintering.The microstructure of composites is analyzed,and the oxidation thermodynamics,oxidation kinetics,microhardness,electrical conductivity and density of the composites are explored in details as follows.Cu-Y alloys with different Y content were prepared by smelting way.With the addition of Y,the grains were refined,and the undissolved Y segregated at the grain boundaries in the form of Cu6Y.The conductivity of the copper alloy decreases with the increase of the Y content.When the Y content is 0.1 wt.%,the conductivity is 98.7%IACS.The hardness of the copper alloy increases with the increase of the Y content,when the Y content is 1 wt.%,the hardness is 85.3 HV.After the in-situ solid-phase reaction of the Cu-Y alloy,an obvious oxidation reaction layer can be observed,and the thickness of the reaction layer is positively correlated with the oxidation time.The microhardness of the reaction layer is greatly improved compared with the unreacted alloy.When the Y content reaches 1 wt.%,the average microhardness of the alloy reaction layer is 100.9 HV,and the average microhardness of the substrate is 85.1 HV.The average particle size of Y2O3 particles generated by liquid phase in-situ reaction is less than 10 nm.In the SAED diagram,it can be seen that Y2O3 has a phase matching relationship with the copper matrix.And the conductivity and microhardness of materials are slightly improved compared to the unreacted alloy.The conductivity of the composite with a Y content of 0.1 wt.%can reach 99.2%IACS,which is better than the solid phase in-situ reaction.When the Y content is 1 wt.%,the microhardness of the composite is 96.5 HV.The samples prepared by spark plasma sintering can be seen that the composites is relatively dense,of which the Cu-1 wt.%Y2O3(900?)sample has the highest density,95.85%.The Cu-Y2O3 composites prepared in this work have nearly microhardness,but the conductivity decreases with the increase of Y2O3 content.The conductivity of the composites prepared by this method is significantly inferior than the sample in the in-situ reaction method.