Research on the New Preparation Process of W-Cu Immiscible Alloy -Solid/Liquid Extrusion (pp. 335-362)
Authors: (Daren Li, Yixiang Cai, Erde Wang, Department of Powder Metallurgy, Guangzhou Research Institute of Non-ferrous Metals, and National Engineering Research Center for Powder Metallurgy of Titanium & Rare Metals, Guangzhou, China, and others)
Abstract: W and Cu are liquid phase immiscible materials. Generally, it is usually prepared by infiltration or liquid active sintering, but the density and properties (specific conductance and hardness) are usually unsatisfied. In order to obtain W-Cu materials in high-grade, the process such as vacuum hot-pressing or HIP is usually used. Because of the low productive efficiency and high cost of vacuum hot-pressing and HIP, the application of W-Cu materials is limitted. The recrystallization temperature of W (>1600℃) is much higher than the melting point of Cu (1083℃). Based on this feature, a new process for W-Cu powder densification called Solid/Liquid Extrusion was introduced by the author in this chapter. In this new technology, the mixed W-Cu composite powder was canned and hot extrusion directly under the temperature near the melting point of Cu without high temperature sintering process. During the extrusion, the melting fluid Cu phase can fill the pores inside material and improve the densification process notably.