For tantalum and tantalum alloy, the main strengthening methods are solution strengthening and precipitation strengthening, and others use wafer and fiber strengthening. But at present, hook solution strengthened tantalum tungsten series alloy is still the most widely used and used. The strengthening of ultrafine crystal is a hot topic in the study of metal strengthening and toughening. However, tantalum and tantalum alloy have great deformation resistance, and the grain is difficult to be refined by hot processing in most cases. The current research has not seen obvious grain superrefinement effect. In addition, 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 molybdenum, which can increase the hardness of jumbo by 1 ~ 3 times, but greatly reduce the plasticity of tantalum. In general, the 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 long time diffusion at high temperature and high vacuum above 2000'C, while oxygen has a low diffusion rate below 2000'C.
Rate, very difficult to remove. Therefore, the pollution of oxygen element is avoided in the process of processing tantalum and tantalum alloy. Tantalum and tantalum alloy structural materials are mostly prepared by vacuum melting. The solid-solution tantalum alloy mainly depends on the circular dissolution of solute elements.
Strengthening, such as TaW alloy, the strength increases with the increase of tungsten content, tungsten content is 12%, the strength is about 650MPa, 15% tungsten content, up to 750MPa. However, the increase of tungsten content makes it more difficult to process the alloy, so the hook content in the alloy is limited to less than 12% at present. The addition of hafnium, carbon and other elements of tantalum alloy on the basis of the macrotungsten alloy, although the high temperature creep resistance is improved, its strength can only reach about 800MPa, and the processing difficulty is further increased.
