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

E. V. Dedyaeva, Post-Graduate Student
T. K. Akopyan, Acting Junior Researcher, e-mail: aktorgom@gmail.com
A. G. Padalko, Head of Laboratory

National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow, Russia:
V. T. Fedotov, Senior Researcher

There was carried out the differential barothermal analysis of phase transformations in Al – 16 Si alloy at argon pressure of 100 MPa and at the temperature of up to 700 ^oС. The differential barothermal analysis technique combines HIP apparatus (HIRP 20/70-200-2000 (ABRA) isostatic press) and classical differential thermal analysis. For the purpose of phase equilibria study, differential thermal analysis cell is located in high-pressure vessel of isostatic press. Measurements were carried out at linear heating and cooling rates of 8 K/min, which were maintained by isostatic press apparatus. Two thermal effects were identified on heating barothermogram. The first peak was determined with aluminum-silicon eutectic melting process. This started process was equal to 582 ^oС, which exceeded eutectic melting temperature under atmospheric pressure by 5 ^oС. In this case, apparently, increasing of eutectic melting temperature is explained by baric coefficients of melting temperature of pure Al, which is ~6,5·10–2 К/МPa. Microstructure of the alloy, solidified at 100 MPa, is significantly coarsened in comparison with initial alloy. Microstructure changes of alloy constituents were determined by slow cooling rate, based on conditions of barothermal experiment. Silicon particles substantially have acicular morphology with inclusions' length of 1000 μm and needles' cross-section of 10 μm. There was defined that microhardness (Al) after differential barothermal analysis is increased by 17%, in comparison with initial state

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