Pacific National University, Khabarovsk, Russia:

E. H. Ri, Head of the Department of Casting and Metals Technology1, Doctor of Technical Sciences, e-mail: erikri999@mail.ru
H. Ri, Professor at the Department of Casting and Metals Technology1, Doctor of Technical Sciences, e-mail: opirus@bk.ru

M. V. Kolisova, Postgraduate Student of Casting, Laboratory Assistant at the Department of Casting and Metals Technology, e-mail: malisun1994@gmail.com

National University of Science and Technology MISiS, Moscow, Russia:
V. B. Deev, Leading Expert of the Department of Metals Fоrming, Doctor of Technical Sciences, e-mail: deev.vb@mail.ru

Structural components in the Al – Sr and Al – Zr alloy alloys have been identified and their micro and nanohardness have been determined using X-ray microanalysis method. Al – Sr ligature (10 wt.%) consists of Al₄Sr strontium aluminid (microhardness — 2799 Mpa and nanohardness — 3230 MPa), strontium eutectic A1 + Al4Sr (microhardness — 721 MPa), metal eutectic A1 + Al₃Fe and pure aluminum (microhardness — 442 MPa and nanohardness — 744 MPa). The structure of the zirconium ligature A1 + Zr (wt.%: 1.62 02; 0.29 Si; 4.11 Zr; the rest — Al) consists of fine dispersed Al₃Zr crystals, of α-solid silicon solution in aluminum, of α + Si eutectic. Microhardness of α-solid solution is 540.8 MPa and that of the eutectic — 983 MPa. Nanohardness of a-solid solution is 741 MPa, and that of  + Al₃Zr eutectic — 8300 MPa. Nanohardness of the Al₃Zr aluminide is 13400 Mpa. The peculiarities of structure formation of the AM4.5Kd alloy components and their properties when modified with the increasing amount of strontium and zirconium (from 0.1 to 0.5 wt.% at a variation interval of 0.1 wt.%) have been investigated using the methods of optical and electro scanning microscopy and micro X-ray analysis. Strontium and zirconium, in the same way as scandium and rare-earth metals (Ce, La) contribute to the refinement of the structural components — -solid solution and eutectic. The regularities of changes in the hardness of the AM4.5Kd alloy, the microhardness and nature of elements distribution in the structural components depending on the amount of strontium and zirconium addition have been established. Microhardness of a-solid solution and hardness of AM4.5Kd alloy vary in extreme dependence with their maxima at 0.1 wt.% Sr and 0.2 wt.% Zr. Scientific background to the established dependencies has been given. Microhardness of the eutectic is under the influence of Scientific background to the established dependencies has been given. Microhardness of the eutectic is under the influence of the nature of elements distribution in the structural components of different composition and origin. Large amounts of strontium and zirconium (more than 0.1 and 0.2 wt.% respectively) cause the eutectic microhardness decrease due to the crystallization of a considerable quantity of high-hard alumides Sr, Cu, Zr, etc., which in its turn embrittles the eutectic and reduces the hardness of the AM4.5Kd alloy.

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