Molybdenum News Center

TZM Alloy Study

In TZM alloy, small amounts of Ti and Zr will react with carbon to form carbon, and more than 94.62% of Zr, more than 90.77% Ti, and more than 41.8% of C will go into to Mo matrix to play solid solution strengthen. The solid solution strengthening of Ti, Zr are obvious than C. Besides, Ti and Zr will react with C to form carbide which plays second phase dispersion strengthening effect in alloy. However, in the alloy solid solution strengthening is the main strengthening way.

TZM alloy after processed hot rolling, whether deformation or not, the tensile fracture contain intergranular brittle fracture. With increasing of deformation, processing fibrous tissue increases as well, so the mechanical properties of the alloys can be strengthened. Besides, the fracture mode from intergranular brittle fracture, cleavage fracture and transgranular cleavage fracture change to mixed mode which is intergranular brittle fracture and quasi-cleavage fracture mixed mode. With deformation increasing, TZM alloy carbide phase distributes uniform and dispersion also improves. Besides, the grain boundary binding force enhances, so the mechanical properties of the alloy improves. When deformation quantity reaches to 90%, the tensile strength of alloy reaches to 846MPa and tensile rate is about 4.3%.

In addition, observed alloy annealing and recrystallization at different temperatures found the hardness as the annealing temperature increases is significantly reduce, and the rate of decline is 0.13 (HV / ℃). After annealing at 1600 ℃, the grain has been fully grown and complete recrystallization, then TZM alloy significantly softened.

Observed TZM alloy microstructure found the second phase particles will hinder grain boundary motion, which make TZM alloy has higher recrystallization temperature. And the low solubility of carbon and oxygen in molybdenum interstitial has low solubility, so it will exist by compound, gathered at the grain boundaries as well as vacancies, dislocations and other defects, thereby reducing the strength of the grain boundaries, impeding dislocation motion. Therefore, during machining, it is easy to form cracks and alloy exhibits a typical brittle at room temperature.

• < Prev
• Next >