Barothermography and microstructure of the hypoeutectic and eutectic alloys in Al–Si system

• Published in: Journal of thermal analysis and calorimetry Vol. 121; no. 1; pp. 485 - 490
• Main Authors: Dediaeva, Elena, Padalko, Anatol, Akopyan, Torgom, Suchkov, Alexei, Fedotov, Vladimir
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-07-2015; Springer
• Subjects: Alloys; Analytical Chemistry; Chemistry; Chemistry and Materials Science; Comparative analysis; Degassing of metals; Inorganic Chemistry; Measurement Science and Instrumentation; Metals; Patients' rights; Physical Chemistry; Polymer Sciences; Precipitation (Meteorology); Specialty metals industry; Thermal expansion coefficient; Aluminum alloys; Thermal analysis; Microstructure; Hot isostatic pressing; Silumins
• DOI: 10.1007/s10973-015-4731-9
• EISSN: 1588-2926
• ISSN: 1388-6150

Differential barothermal analysis (DBA or HP-DTA) of the phase transformations in hypoeutectic Al-10 at.% Si and eutectic Al-12 at.% Si alloys was carried out at 100 MPa of argon pressure and at temperatures up to 700 °C. Liquidus temperature of Al-10 at.% Si is reduced during melting and crystallization by 3–4 °C as compared with the atmospheric pressure data. Increase in the eutectic transformation L → (Al) + Si temperature up to 580–581 °C during heating was found for the Al-10 at.% Si and Al-12 at.% Si alloys. According to the barothermography data, a slight thermal effect at 553 °C is detected for both alloys, which was identified as the decomposition of aluminum-based solid solution and precipitation of silicon particles. The improvement of silicon phase morphology for Al-10 at.% Si and Al-12 at.% Si alloys after hot isostatic pressing (HIP) at the pressure of 100 MPa and temperature of 550 °C was found. No porosity in the alloy has been established after HIP treatment. After HIP thermal expansion, coefficients of the alloy are noticeably decreased by 25 (Al-10 at.% Si) and 50 % (Al-12 at.% Si).