A novel high density W-30Cu alloy prepared via hydrothermal synthesis-co-reduction and canned hot extrusion methods

Abstract

We report herein the successful synthesis of in situ nanocomposite W-30Cu as powder via the hydrothermal approach combined with the co-reduction process, having sodium tungstate and copper nitrate as starting materials. The cold isostatic pressing, vacuum sintering and canned hot extrusion technology have been employed in order to improve the properties of the W-30Cu alloy. The impact of preparation’s methodologies on the microstructure, mechanical and physical properties have been investigated by the means of X-ray diffractometry (XRD); scanning electron (SEM); field emission electron (FE-SEM) and high-resolution electron (HRTEM) microscopies; conductivity meter and Brinell hardness tester. The results indicate that the precursor powder had a coating structure leading to W and Cu elements in situ symbiosis during the co-reduction period. The W-Cu reductive powder displayed an unstable core-shell structure of W coated Cu. During hot extrusion, the rapid mass transport, sintering mode conversion and bridge effect elimination enhance the density and properties of the W-Cu composites. The microstructure of the W-Cu composite exhibited a uniform distribution of W within the Cu phase with intact Cu network structure as well as fine W particles. The relative density, conductivity and hardness of the final product have reached 99.2%, 43.3% IACS and 214 HB, respectively, which are superior compared to those obtained by the traditional powder metallurgy methods.