Rare earth doped TZM alloy
TZM alloy is the most widely used molybdenum alloy. It has many excellent properties and is often used to manufacture high-temperature structural parts used in different fields. With the development of industry, further requirements have been put forward for the performance of TZM alloys. Doping a small amount of rare earth elements in TZM alloys can reduce the grain size, increase the plastic-to-brittle transition temperature, and improve the recrystallization temperature, high-temperature strength, plasticity, and high-temperature creep resistance.
Doping a small amount of rare earth elements can not only improve the properties of the alloy, but also expand its application range. Common rare earth doping elements include La and Re. La and Re oxides were prepared by powder metallurgy, and La2O3-TZM alloy and Re-TZM alloy were obtained by doping respectively.
Mechanical properties of La2O3-TZM alloy: The tensile strength of La2O3-TZM alloy is 119MPa higher than that of undoped TZM alloy, the yield strength is 49MPa higher, and the elongation is 4.3% higher. This is mainly because dispersed La2O3 has a strong dispersion strengthening effect, and La2O3 can also produce dislocations, so the La2O3-TZM alloy has higher strength. In addition, the second phase particles are smaller and more uniformly distributed than TZM alloys, so the plastic deformation resistance and yield strength are high. Overall, it has better mechanical properties than TZM alloy.
Fracture morphology of La2O3 TZM alloy: The fracture morphology of TZM alloy is brittle intergranular fracture, and the fracture morphology of La2O3-TZM alloy is mixed dimple-quasi-cleavage fracture. The dispersed La2O3 particles are evenly distributed at the grain boundaries and inside the crystal, resulting in an increase in the interface surface area. Impurities such as oxygen, carbon, and nitrogen will preferentially accumulate on the grain boundaries and La2O3 particle surfaces, greatly reducing the impurity concentration, enhancing the grain boundary bonding strength, and improving the toughness of TZM alloys.
TZM-Re alloy performance analysis: Re element plays a powerful "rhenium" effect in TZM alloy. Doping Re can not only improve the high-temperature properties of the alloy, but also improve the room-temperature properties of the alloy. As the Re doping amount increases, the bending strength of TZM alloy does not increase significantly. Mainly because the alloy material has not yet completely plastically deformed before fracture. Generally speaking, the strength of Re-TZM alloy is slightly lower, but TZM-Re alloy shows certain toughness at room temperature.
Your message must be between 20-3,000 characters!