The invention relates to a method for preparing reinforced tantalum and tantalum alloy materials, in particular to a method for strengthening the crystal structure of tantalum and tantalum alloy materials.
There are many ways to strengthen metal, such as circular solution strengthening, precipitation strengthening, dispersion strengthening, work hardening, fine grain strengthening and particle strengthening, fiber strengthening, whisker strengthening and lamellar strengthening. In addition to fine grain strengthening, other strengthening methods mainly use solute atoms and isolated in the matrix of the second phase (precipitation phase, dispersion phase, external particles, fibers, whiskers, etc.) to prevent dislocation movement, in order to improve the deformation resistance of metal. Fine grain strengthening takes advantage of the fact that the grain boundary strength in polycrystals is higher than the ingrain strength at room temperature by increasing the number of grain boundaries. Work hardening uses the increase of dislocation density to cause crystal lattice distortion and dislocation entanglement to prevent dislocation movement and strengthen metal.
For tantalum and tantalum alloy, the main strengthening methods are solution strengthening and precipitation strengthening, and other strengthening methods are wafer strengthening and fiber strengthening. However, the most widely used and widely used tantalum tungsten alloys are still reinforced by hook solution. Superfine grain strengthening is a hot topic in metal strengthening and toughening. However, the deformation resistance of tantalum and tantalum alloy is large, and it is difficult to refine the grain due to thermal processing in most cases. So far, no obvious superrefinement effect has been found. In addition, tantalum is often used in high temperature structure, and ultra-fine 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 molybdenum by 1 ~ 3 times, but greatly reduce the plasticity of tantalum. Generally, the oxygen in tantalum, as a harmful element that damages plasticity and toughness, should be removed as little as possible. The removal of solid solution oxygen from tantalum requires long-term diffusion at high temperature and high vacuum above 2000'C, but below 2000'C, oxygen has a low diffusion rate in Tantalum.
