Modern production enterprises pay close attention on the improvement of W-Cu alloy property. The alloy is composed of mixed W-Cu two-phase monomers, which is insoluble and not develop into intermetallic compound, so it is called typical pseudo alloy. Modern production enterprises want to get W-Cu composite with higher property and higher density, it is necessary to overcome the mutual insolubility of tungsten and copper, and combine the characteristics of tungsten-copper composite products to make compact pressure processing in order to improve compactness and comprehensive property to meet the requirements of modern production.
Now there are two ways to improve W-Cu alloy property, one is to prepare W-Cu ultrafine powder, the other is to improve the pressure densification technique of W-Cu composite.
1.0 Prepare W-Cu ultrafine powder
There are six main methods to prepare ultrafine composite raw powder of tungsten copper including mechanical alloying method, sol-gel method, spray drying method, oxide co- reduction method, mechano thermochemical synthesis method and precipitation method.
1.1 Mechanical alloying method is to put W-Cu raw material powder into high performance ball mill for ball milling, and get refined raw material powder by controlling time and rotating speed;
1.2 W-Cu composite powder prepared by sol-gel method has uniform particle size, high purity and high surface activity, and is easy to be prepared.
1.3 The tungsten and copper oxide powders can only be obtained by spray drying, and ultrafine tungsten copper composite powders can be obtained by reduction method.
1.4 The oxide co-reduction method is that tungsten and copper oxides are easier to mix and distribute than single metal, and the fully dispersed tungsten and copper oxides are reduced to obtain ultrafine and uniform tungsten copper composite powder.
1.5 The mechanical thermochemical synthesis method is to use tungsten and copper oxide powder to prepare powder by mechanical alloying ball mill, and then use reduction method to obtain composite powder.
1.6 Precipitation method is to obtain W-Cu composite powder by liquid phase precipitation, calcination, reduction and other technique methods.
In actual production and application many methods are usually combined to get ultrafine W-Cu composite powder to meet various requirements of production.
2.0 To improve the pressure densification process of W-Cu composite
To further improve the compactness and the characteristic of W-Cu composite products, the pressure compactness processing is carried out according to the product variety, shape and so on. Presently the main pressure processing methods are available include hot isostatic pressing, hydrostatic extrusion, hot forging and so on.
2.1 Hot isostatic pressing method can eliminate the defects such as voids and shrinkage cavities of W-Cu composite. This process makes full use of the ductility of copper and improves the materials property, but the equipment cost is high and the efficiency is low.
2.2 Hydrostatic extrusion method is to transfer the force to the material using fluid medium, which will be more helpful for the uniformity of deformation. This method can greatly improve the density, strength and conductivity of W-Cu composite.
2.3 Hot forging, hot rolling and other common deformation processes also improve the property of W-Cu composite.
