Structure and properties of powder alloys based on titanium aluminides after heat treatment
DOI:
https://doi.org/10.46299/j.isjea.20220104.09Keywords:
titanium aluminide, , hot isostatic pressing, powder, particle, porosityAbstract
It is shown that materials consolidated from mechanically synthesized powders by hot isostatic pressing and subjected to additional annealing have structural heredity and have an unusually high microhardness characteristic of nanostructured formations. Hot isostatic pressing makes it possible to realize the effect of structural heredity in materials sintered from powders. Scandium microalloying of Ti-Al powder alloy provides the best combination of ductility and strength characteristics of hot-pressed materials due to the formation of a refined microstructure with nanosized grains at high temperatures and loads.
One of the possible ways to improve the characteristics of the studied class of materials is the complex development of modes for obtaining non-porous materials while maintaining the nanostructure. To accurately assess the properties of the synthesized powder materials, standard complex mechanical tests are required.
Thus, an alloy based on Ti-Al-Sc subjected to HIP at 12000C has optimal mechanical properties. A material with such a microstructure can be considered promising for achieving a satisfactory combination of high crack resistance at room temperature and creep resistance at elevated temperatures due to the presence of the α2 phase and the finest inclusions of scandium oxide at the grain boundaries.
It can be assumed that diffusion processes increase at 12000C, the degree of lattice amorphization decreases, scandium and oxygen dissolved in the lattice leave it and form nanodispersed oxides, the most probable place of accumulation of which is the boundaries of a microsized subgrain. At the same time, scandium, refining the grain from oxygen dissolved in the lattice, makes the material more plastic, and the hereditary presence of scandium on the surface of the initial particles, along with an increased oxygen content there, can have a stabilizing effect on the boundaries of subgrains due to the formation of highly dispersed oxide inclusions.
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