A. A. Baikov Institute of Metallurgy and Materials Science of Russian Academy of Sciences, Moscow, Russia:

T. K. Akopyan, Acting Junior Researcher, e-mail: aktorgom@gmail.com

National University of Science and Technology “MISiS”, Moscow, Russia:

N. A. Belov, Professor, Director of Engineering Center “Innovation Casting Technologies and Materials”

A. N. Alabin, Head of Department of Engineering Center “Innovation Casting Technologies and Materials”

Belgorod State National Research University, Belgorod, Russia:
R. O. Kaybyshev, Head of Laboratory of Mechanical Properties of Nanostructure and Heat-Resistance Materials

Barothermal treatment by liquid hot isostatic pressing (LHIP) was used for casts of new lean alloyed high strength casting aluminum alloy Al₆Zn_0.5Ni (АЦ6Н0,5Ж) (on the basis of Al – Zn – Mg – Ni – Fe system) for two modes with different isothermal exposure temperature: t₁ = 490 ^oC (LHIP1) and t₁ = 510 ^oC (LHIP2). The alloy was melted in laboratory resistance electric furnace in graphite-chamotte crucible. Casting was carried out into steel mold. Microstructure of casting and heat-treated samples was studied with an Axio Observer MAT optical microscope and JSM-6610LV scanning electron microscope. Microstructure of the alloy after heat treatment without LHIP contains large irregularly shaped shrinkage pores with an average size of 10–60 μm. Results show that 2 minutes of LHIP at the pressure of 120 MPa lead to significant removing of porosity. LHIP eliminates shrinkage porosity, which highly improves mechanical properties. LHIP and heat treatment on the T6 regime provides increase of UTS by 20%, fracture elongation by 6 times and fatigue strength by 1.5 times. Results show the possibility of achieving of high mechanical properties of aluminum castings, which allows their use to replace the commercial high-strength casting alloys of Al – Cu system (particularly AM5).

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