Method for preparing reinforced tantalum and tantalum alloy materials

For tantalum and tantalum alloys, the main strengthening methods are solution strengthening and precipitation strengthening, and others use wafer crystal and fiber strengthening. But at present, the largest and most widely used alloys are still tantalum tungsten series reinforced with tungsten solution. Superfine crystal strengthening is a hot topic in metal strengthening and toughening. However, tantalum and tantalum alloy have great deformation resistance, and in most cases, hot processing is adopted, so it is difficult to refine the grain. The current research has not seen obvious grain superrefinement effect. Moreover, tantalum is often used in high-temperature structure, and superfine crystal strengthening is not suitable for high-temperature working environment.

Oxygen has the effect of solid solution strengthening in tantalum, which can increase the hardness of tantalum by 1 ~ 3 times, but greatly reduce the plasticity of tantalum. Under normal circumstances, solid dissolved oxygen in tantalum, as a harmful element that damages plasticity, should be removed as far as possible. The removal of solid dissolved oxygen from tantalum requires a high temperature above 2000℃ and a high vacuum for a long time, while below 2000℃, oxygen has a low diffusion rate in tantalum and is difficult to remove. Therefore, at present, the pollution of oxygen element is avoided in the processing process of tantalum and tantalum alloy.

Tantalum and tantalum alloy structural materials are mostly prepared by vacuum melting. Solid solution tantalum alloys mainly rely on solid solution strengthening of solute elements, such as TaW alloy, whose strength increases with the increase of tungsten content. When the tungsten content is 12%, the strength is about 650MPa, and when the tungsten content is 15%, the maximum strength is 750MPa. However, the increase in tungsten content makes the processing of the alloy more difficult, so the current tungsten content in the alloy is limited to less than 12%. On the basis of tantalum tungsten alloy, hafnium, carbon and other elements are added into the multi-element tantalum alloy. Although the high temperature creep resistance is improved, its strength can only reach about 800MPa, and the processing difficulty is further increased.