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 (Ti 5 Si 3 ) in aluminide (TiAl) matrix. The hardness of the material reaches 865 ± 42 HV 5.

Intermetallic compounds based on Ti-Al- (Si) are attractive materials with good thermal stability and low density. However, the production of these materials is quite complicated. Partially modified conventional methods of melting metallurgy are most often used due to availability, possible high productivity, and relatively low production costs. Therefore, some technologies for the production of intermetallics based on Ti-Al are currently available, but with certain disadvantages, which are caused by poor casting properties or extreme reactivity of the melt with crucibles. Some shortcomings can be eliminated by modifying the melting technology, which contributes to increasing the cost of the process. The work deals with the preparation of Ti-Al-Si intermetallic compounds with different contents of aluminum and silicon, which were produced by centrifugal casting in an induction vacuum furnace Linn Supercast-Titan. This process could contribute to the commercial use of these alloys in the future. For this research, the TiAl15Si15(in wt.%) alloy was selected, which represents a balanced ratio of aluminides and silicides in its structure, and the TiAl35Si5 alloy, which due to the lower silicon content allows better melting conditions, especially with regard to the melting temperature. This alloy was also investigated after HIP (“Hot Isostatic Pressing”) treatment.

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Ti-Al-Si alloys are among the most promising intermetallics, which show a combination of low density and good oxidation resistance. These positives predetermine Ti-Al-Si alloys for applications in the automotive and aerospace industries. In the future, they could substitute existing materials for high-temperature applications (stainless steels, and especially nickel alloys), that high density significantly limits their application. The use of intermetallic compounds based on Ti-Al-Si would therefore lead in particular to a reduction of the weight of the structures, which is highly desirable in the aerospace industry. Due to the lightweight construction, fuel consumption and transport costs in general would also be reduced. The disadvantage of Ti-Al-Si alloys is their brittleness at room temperature. Decrease of brittleness can be achieved by suitable chemical composition and also by choosing the suitable preparation. Therefore, powder metallurgy processes appear to be the right way to prepare these intermetallics. This work deals with the preparation of intermetallic alloys based on Ti-Al-Si system with the low content of silicon by powder metallurgy using mechanical alloying and followed compaction by Spark Plasma Sintering.

The intermetallics based on Ti-Al system are a relatively new class of high-temperature construction materials that combine unique physical and mechanical properties for use in aircraft engines, industrial gas turbines, or automotive industry. They are characterized by low density, good mechanical properties at high temperatures and good oxidation resistance. Addition of silicon into the Ti-Al alloys improves oxidation resistance and ultimate tensile strength in compression, but the complicated production limits wider use of these Ti-Al-Si intermetallic alloys. In this work, two main technologies of preparation of intermetallic compounds will be compared-melting and powder metallurgy.