Effect of Alloying Elements on Mechanical Properties of Titanium

The main ways of strengthening titanium alloys are solid solution strengthening and dispersion strengthening. The former is to improve the performance of the alloy by increasing the solid solubility of the α-phase and β-phase, and the latter is to achieve the purpose of strengthening by obtaining highly dispersed α+β or α+ intermetallic compounds through heat treatment. Titanium alloy: It is difficult to adjust through the structure, while meeting the high strength level, it still maintains sufficient plasticity and toughness. Among the α-stabilizing elements, Al has the most significant solid-solution strengthening effect. The β-stable elements are preferentially dissolved in the β-phase, so the β-phase has stronger strength and hardness. The average strength of the alloy increases with the increase of the proportion of the β-phase in the structure. When the α-phase and β-phase account for 50% each, the strength reaches the peak. , continue to increase the number of β phases, but the strength decreases. For heat-resistant alloys used at high temperatures for a long time, the existence of inactive eutectoid elements will reduce the thermal stability of the material. When approaching the phase transition temperature, the stability of the structure decreases and the atomic activity increases, which promotes the softening of the metal. Therefore, the composition of heat-resistant titanium alloy should be dominated by α-stable elements and neutral elements, and the effect of β-stable elements is generally poor. Only those elements such as molybdenum, tungsten and silicon and copper with high eutectoid transformation that can strongly improve the bonding force of titanium atoms can effectively increase the thermal strength of the alloy within the appropriate solubility range. The heat-resistant titanium alloy should have a single-phase structure, and α-type or near-α-type alloys are generally used as materials for high-temperature work.