Laskovets V. Features of influence of titanium on crystallization process, structure and properties of alloys on a basis to aluminum - copper system.

Dissertation work is devoted to a research of influence of micro additives of titanium on properties of melt, crystallization process, structure and characteristics of alloys of the Al-Cu system and development of optimum compositions of alloys for irregular shape castings of responsible appointment.It is established that dependences of influence of content of the titan on crystallization parameters, tendency to formation of hot cracks, structure and mechanical properties have extreme character and have an optimum in a narrow concentration interval from 0,28 to 0,32 %.Optimum conditions under which grain refinement and properties of alloys increase are defined. They are related to a special condition of the melt and are characterized by high parameters of undercooling in case of crystallization of a solid solution. It is connected to formation of clusters with a non-crystalline short-range order that leads to a considerable change of the mechanism of structure formation in which origin and growth of crystals of solid solution occurs in the undercooled melt.Thereof, diffusive and mass-exchanged processes are considerably slowed down, that leads to domination of process of incipience of crystals over process of their growth. Grain refinement and increase in properties of alloy turns out to be consequence of what.New foundry high-strength aluminum alloy which in comparison with industrial alloys AМ4,5Кд and Alufont 52 has low tendency to formation of hot cracks and the high mechanical properties is developed.