共还原工艺对W-25Cu纳米复合粉体及其挤压组织与性能的影响

Extrusion Microstructure and Properties of W-25Cu Nano-Composite Powders with Co-Reduction Process

以钨酸钠（Na2WO4·2H2O）和硝酸铜（Cu（NO3）2·3H2O）为原料,采用水热-共还原工艺制备W-25Cu纳米复合粉末,包套热挤压工艺制备细晶W-25Cu合金。利用X射线衍射仪（XRD）、扫描电镜（SEM）和透射电镜（TEM）等分析测试手段研究了共还原工艺对W-25Cu复合粉体及其挤压组织与性能的影响。研究结果表明：相比于一段还原工艺,两段还原过程中先还原出的Cu相能够通过增加异相形核细化晶粒,对后续W相的还原具有催化与细化作用。两段还原得到的W-Cu复合粉体微观组织呈典型的钨包铜结构,粒度达到纳米级,分散性良好。烧结热挤压后,制备的合金具有细密组织与良好性能,致密度达到99.52%,硬度提高到HB 272,导电率提高到52.8%IACS,抗拉强度达到282 MPa。

The W-25 Cu nano-composite powders were fabricated by hydrothermal-coreduction method with sodium tungstate and cupric nitrate,while W-25 Cu alloy with fine grain was obtained via package hot extrusion process. X-ray diffractometer（XRD）,scanning electron microscope（SEM）,energy dispersive spectrometer（EDS） and high resolution transmission electron microscopy（TEM）were employed to observe the ingredient,morphology and microstructure of the W-25 Cu powers and alloy,respectively. The results showed that,compared with one-step reduction,the Cu reduced initially in the two-step reduction could refine grain size by increasing heterogeneous nucleation,which played important roles in catalytic action and refinement effect of W. The microstructure of W-Cu composites obtained by two-step reduction showed typical Cu-coated W structure with fine grain size and uniform dispersion. The alloy prepared by two-step reduction and hot-extrusion sinter possessed fine organization and good performance with 99. 52% of density,HB272 of hardness and 52. 8% IACS of conductivity.