Actual Problems in Machine Building 2021 Vol.8 N1-2

Актуальные проблемы в машиностроении. Том 8. № 1-2. 2021 Материаловедение в машиностроении ____________________________________________________________________ 91 NEW MODIFIER FOR АLUMINIUM ALLOYS WITH HIGH SILICIUM CONTENT Afanasyev V.K. 1 , D.Sc. (Engineering), Professor, e-mail: in_afanaseva@mail.ru Popova M.V. 1 , D.Sc. (Engineering), Professor, e-mail: m.popova@rdtc.ru Prudnikov A.N. , D.Sc. (Engineering), Professor, e-mail: a.prudnikov@mail.ru Sagalakova M.M. 2 , Ph.D. (Engineering), Associate Professor, e-mail: m_sagalakova@mail.ru 1 Siberian State Industrial University, 42 Kirov st., Novokuznetsk, 654007, Russian Federation 2 Khakass Technical Institute of the Branch of Siberian Federal University, 27 Shchetinkina st., Abakan, 655017, Russian Federation Abstract Introduction. Modification is widely used to improve structural characteristics and mechanical properties of high-silicon silumins. For silumines of the eutectic composition, the task of modifying the structure is complicated by the fact that it is necessary to achieve dispersion of crystals not only eutectic, but also primary silicon. Therefore, the development of methods for modifying high-silicon alloys of the Al-Si system is still an urgent task. The purpose of the work: is to study the structure and mechanical properties of aluminum alloys with a 15-50% silicon after modifying them with a mixture of phosphorous copper, lithium hydride and boron. Research methods: metallographic analysis, determination of mechanical properties. Results and discussion. It was found that the modification by the proposed method contributes to the formation of the fine structure of Al - (15÷50) % Si alloys, especially after high-speed crystallization. The greatest effect is achieved for alloys containing Si 30-50%. It is shown that treatment of liquid alloy by the complex modifier (Cu 3 P + LiH + В) in combination with hydrogen saturation and high speed of crystallization significantly increases mechanical strength and plasticity of Al-alloys (15÷50) of Si %: strength increases by 1.5-2.6 times, relative lengthening - by 1.8-2.0 times. Use of the developed method makes it possible to obtain high mechanical properties in ingots already in cast state, which eliminates the need for strengthening heat treatment. Keywords Aluminium, Silicium, modification, microstructure strength, ductility