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This work is devoted to the preparation of alloys based on intermetallic compounds in the Ti-Al-Si system by powder metallurgy using mechanical alloying and the spark plasma sintering (SPS) method. The aim was to describe the formation of intermetallic phases during mechanical alloying of TiAl15Si15 (wt-%) alloy and to consolidate the powder prepared by optimised conditions. Phase composition, microstructure and hardness of compacted alloy were determined. Four hours of mechanical alloying is sufficient time for preparation of pure elements free material composed only of intermetallic phases. After consolidation, the TiAl15Si15 alloy has a homogeneous structure composed of silicide (Ti5Si3) in aluminide (TiAl) matrix. The hardness of the material reaches 865 ± 42 HV 5. [ABSTRACT FROM AUTHOR]

Ti–Al–Si alloys are prospective material for high-temperature applications. Due to low density, good mechanical properties, and oxidation resistance, these intermetallic alloys can be used in the aerospace and automobile industries. Ti–Al–Si alloys were prepared by powder metallurgy using reactive sintering, milling, and spark plasma sintering. One of the novel SPS techniques is high-pressure spark plasma sintering (HP SPS), which was tested in this work and applied to a Ti–10Al–20Si intermetallic alloy using a pressure of 6 GPa and temperatures ranging from 1318 K (1045 °C) to 1597 K (1324 °C). The low-porosity consolidated samples consist of Ti5Si3 silicides in an aluminide (TiAl) matrix. The hardness varied between 720 and 892 HV 5. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the dependence of microstructure of Fe–Al–Si alloy on conditions of reactive sintering was studied. It was shown that heating rate strongly affects the structure of this alloy. The microstructure consisting of uniformly distributed Al2Fe3Si3 particles in Al2FeSi matrix can only be obtained in this material by rapid heating (over 300Kmin−1). Sufficient reactive sintering temperature to obtain Al2Fe3Si3–Al2FeSi two-phase structure is 750°C. Further increase of the reaction temperature reduces porosity but causes a growth of Al2Fe3Si3 particles. Reactive sintering process is completed during less than 10min in the investigated material. Temperatures over 1050°C produce material composed of FeSi, FeAl and Al2Fe3Si3 phases. However, strongly exothermal reaction of FeSi formation causes melting of the sample. [Copyright &y& Elsevier]

Abstract: In this work, Ti–Al–Si alloys were prepared by reactive sintering. The contents of silicon and aluminium ranged between 0–30wt.% and 0–36wt.%, respectively. Powders of titanium, aluminum, silicon and AlSi30 master alloy prepared by mechanical machining and/or milling were used for sintering. Powders were blended and pressed at room temperature. Sintering was carried out at 900°C for 30min. It was found that it is possible to produce compact materials with the structure corresponding to the as-cast materials when silicon is in the range of 15–20wt.% and aluminium content between 8 and 30wt.%. It was shown that these materials contain two phases—Ti5Si3 and TiAl. The central porosity can be reduced by induction heating. [Copyright &y& Elsevier]

This work aims to describe the formation of intermetallics in the Ni-Ti-Al system in dependence on the heating rate, which has been determined previously as the crucial factor of thermal explosion self-propagating synthesis (TE-SHS). The tested alloys contained 1–7 wt % aluminum. Thermal analysis has been realized by the optical pyrometer under the conditions of high heating rates up to 110 °C·min−1. TE-SHS process in Ni-Ti-Al system is initiated by exothermic reaction of nickel aluminides Ni2Al3 and NiAl3 at the temperature of 535–610 °C. The next reactions occur in dependence on the heating rate. Samples containing 1–3 wt % of aluminum exhibit the similar initiation temperature as Ni-Ti binary mixture. The samples containing 5 wt % and more of aluminum were fully reacted after sintering at 800 °C with the heating rate of 300 °C·min−1 and the initiation temperature of the TE-SHS was observed close to Al-Al3Ni eutectic temperature (between 630–640 °C). [ABSTRACT FROM AUTHOR]

• Ti-Al-Si-X (X˭Co, Cr, Fe, Mo, Nb, Ni) alloys prepared using mechanical alloying and Spark Plasma Sintering. • Alloys have fine-grained and homogeneous microstructure with low porosity. • Alloyed elements increased hardness and compressive strength values. Intermetallic alloys based on Ti-Al-Si system are significant for their excellent high-temperature properties, especially for resistance against oxidation and for achieving good mechanical properties at elevated temperatures. The main problem of these materials is high brittleness at room temperature. In the previous work, selected alloying elements were added into the Ti-Al-Si alloys prepared by reactive sintering, but the properties did not meet the requirements for subsequent use in the automotive or aerospace industry, since the materials had a very porous microstructure. Here, the addition of cobalt, chromium, iron, molybdenum, niobium and nickel into the TiAl15Si15 alloy prepared by mechanical alloying and Spark Plasma Sintering is tested and it is expected to improve the mechanical and high-temperature properties. In this paper, the Ti-Al-Si alloys have been assessed on basis of microstructure, phase composition, mechanical and tribological properties, such as hardness, fracture toughness and compressive strength. Cyclic oxidation tests were performed for 400 h at the temperatures of 800 and 1000 °C. The cyclic oxidation tests simulate industrial processes, where the material is alternately exposed to elevated temperature and subsequent cooling (eg, engine components). From the viewpoint of most of the tested properties, alloying by niobium seems to be the most promising. [ABSTRACT FROM AUTHOR]