Different Annealing Temperatures Influence TZM Alloy’s Fracture Morphology

Different annealing temperatures, tensile fracture morphology of TZM alloy is not the same. When annealing temperature is 850 ℃, the tensile fracture of TZM alloy is mainly transgranular fracture. There is a significant cleavage step on the fracture. And there are a lot of holes in fracture grain boundary. Besides, these holes are formed crack sources in the stretching process which causes alloy break by interconnected. Annealed at 1000 ℃, the fracture has obvious river-like pattern and cleavage step. When the cracks expansion will connect with dislocation and therefore will generate cleavage step. Meanwhile, the alloy before breaking through a lot of strain, so there has been a lot of tearing ridge on cleavage surface. When the annealing temperature is 1150 ℃, the fracture characteristics is similar to 1000 ℃ fracture characteristics, but the degree of cleavage fracture has improved, so the breaking plastic of alloy also increased.

Recrystallization temperature of TZM alloy is about 1200 ℃, when the annealing temperature exceeds the recrystallization temperature, the alloy has coarse grains, the fracture surface is relatively flat. The fracture is mainly transgranular fracture and ductile fracture which is mean plastic of alloy has been further increase. But there have been many irregularities particles and pits in the alloy and there are enhanced phase precipitate in local area. This shows the high annealing temperature weakened dispersion strengthen and have a certain influence on the mechanical properties of the alloys. Therefore, the annealing temperature should be controlled below the recrystallization temperature of TZM alloy.

Deformation Degree Influence Titanium Zirconium Molybdenum Alloy’s Organization Structure

By observing different deformation degrees’ low magnification and high-powered microstructure photograph of titanium zirconium molybdenum (TZM) alloys was found, low-temperature sintering alloy billet has grain fine and uniform structure. After rolling, with deformation degree increases, the original equiaxed grain components along the deformation direction extending and carbide phase dispersed evenly, so the dispersion strengthening effect is more pronounced. When the deformation degree increases, the organization structure of grains becomes blurred, but the grain size and form are consistency good, a fiber distribution. And Mo grains coexist with each other so the intergranular binding force strong and TZM alloy susceptibility to crack greatly reduced. Meanwhile, the alloy grain boundary inside impurity segregation decreased, tensile strength and toughness has been greatly improved. As the deformation increases, the overall variation of the alloy structure is as follows: a large amount of deformation of TZM alloys occur carbide phase dispersed uniformly, high dispersion, fibrous tissue increased and more refined, the final alloy room temperature mechanical properties significantly improved.

Deformation Temperature Influence Titanium Zirconium Molybdenum Alloy’S Organization Structure

Deformation temperature is one of the important factors affecting the titanium zirconium molybdenum (TZM) alloy organizatiom structure, and changes in the organizational structure of the alloy can also cause changes in their properties. After study the influence of different deformation temperature on TZM alloy found that when the deformation temperature is lower than 1150 ℃, due to the deformation resistance of titanium zirconium molybdenum alloy is large so the cracking becomes serious which can not employ subsequent processing. As the deformation temperature increase, TZM alloy has no cracking phenomenon. Besides, the deformation resistance of TZM alloy decreased and the plasticity increase. When the deformation temperature at range of 1300~1350 ℃, the organizational structure of the alloy is a fibrous elongated grains which are mutually overlapping staggered. Besides, the arrangement between the grains very compact and grain boundaries is straight which has fewer voids. However, if the deformation temperature above 1350 ℃, the grain size of the alloy TZM can cause excessive tissue coarsening. During rolling the alloy will pass through a large thermal deformation, so that the ductility of the alloy to give the corresponding increase, but there is a big internal tissue distortion after deformation. If subsequent processing steps still using higher heating temperature, it is easy to make a crude alloy, reduce performance TZM alloy.

La2O3 Influence TZM Alloy’s Mechanical Properties

La2O3 particles can not only improve the recrystallization temperature of TZM alloy, but also can improve strength, elongation and other mechanical properties. The strengthen role of the La2O3 particles is mainly due La2O3 particles and dislocations can occurs strong interaction. There are a large number of dislocations in TZM alloy are firmly pinned by La2O3 particles. If dislocation wants to break the pinning of particle should generate greater stress, thus room temperature tensile strength of TZM-La2O3 alloy is better than TZM alloy which has significantly improved. With the La2O3 particle content increase, the interaction between particles and the dislocation enhance and pinning effect to dislocation is also significantly enhanced. Strengthening role of La2O3 particles become more pronounced.

TZM alloy after adding La2O3 particles exhibit good ductility, mainly because of a microporous relaxation mechanism of La2O3. When introduced the small dispersed second phase La2O3 particles in into Mo, on one hand, it makes deformation more uniform. On the other hand, a large number of dislocations are nailed it, in favor of delaying the formation of intergranular cracks. With the further deepening of deformation, cracks will expand or stretch into the cavity, and these holes allow stress relaxation, thereby increasing the tensile properties of the alloy.