Research On Properties Of Two Kinds Of W-Cu Composite Powder By Hot Pressed Sintering And Plastic Deformation

Tungsten copper composite has been widely used in electrical and electronicfields as electrical contact, electro-discharge electrodes and electronic packagingmaterials due to its excellent electrical and mechanical properties. In order toexpand its product categories and application fields, the density and mechanicalproperties of tungsten copper composite should be improved further.In this paper, Tungsten copper composites were fabricated through coldpressing, vacuum hot-pressing sintering and hot extrusion with steel sleeve, acomparative processability of two kinds of W-Cu composite powders which wasprepared by spray-drying method and mechanical alloying were studied. Inaddition, the drawing performance of W-90wt.%Cu composites show that it can bedrawn into different wire sizes with excellent electrical conductivity andmechanical properties.Experiments show that by adopting a combination of common mould pressingand cold isostatic pressing method, W-40wt.%Cu composite can be transformedinto a billet with high density. As a result, it lead to the billet could be sinteredthrough vacuum hot-pressing at a low temperature and obtain uniformmicrostructure as well as high comprehensive physical properties. The effects ofsintering temperature on densification were introduced in detail, then the sinteringcharacteristics of tungsten copper were explained by the theory of materialdiffusion and plastic flow, results show that the sintered density was associatedwith particle size and sintering activity of the powder, and the sintering activityhas the highest impact. In addition, the densification effect of different sinteringbillets by hot extrusion demonstrated that the powder prepared by spray-dryingmethod would produce better physical properties than the other one prepared bymechanical alloying. The analysis of mechanical properties of W-Cu compositematerials indicated that the relationship of elastic modulus betweenwork-hardening capacity and density can be explained by the definition of damagevariable based on damage mechanics，its application conditions were provided inthis paper.At last, the research on synthesis process of W-90wt.%Cu compositematerials show that densification through sintering and hot extrusion broughtbetter performance in the properties of W-Cu materials than that through onlyhot extrusion. Tungsten copper wire has a higher tensile strength and goodelectrical conductivity, different sizes of wire can be made by multiple-pass hot drawing with large deformation as well as cold drawing with small deformationper pass. The analysis of results indicate that the main factor influencing drawingproperties of W-Cu is the continuity and uniformity of the copper phase, in orderto realize better performance, W-Cu composites should be made through acombination of low-temperature sintering and hot extrusion processes.