Abstract
The effect of two processing routes on chemical composition, microstructure and mechanical properties of plasma melted intermetallic ingots with nominal composition Ti-46Al-8Ta (at.%) was studied. The semi-products for plasma melting were prepared by: (i) cold single action compaction of initial pure materials and (ii) induction melting of binary master alloy with nominal composition Al-14Ta (at.%), its casting in a copper mould and mixing with Ti sponge. The applied processing routes and selected parameters of plasma melting results in a full dissolution of initial materials and homogeneous distribution of alloying elements in the plasma melted Ti-Al-Ta ingots. The ingots prepared from the cold compacted materials show high burnout of Al up to 3.7 at.% and contamination by O up to 1.31 at.%. Content of Al is well adjusted in the plasma melted ingots prepared from the master alloy mixed with Ti sponge and content of O is reduced to 0.69 at.%. The morphology of dendrites within columnar and equiaxed grains indicates solidification via β (Ti-based solid solution with cubic crystal structure) primary solidification phase. The microstructure of the grains is lamellar and consists of α₂ (Ti₃Al) and γ (TiAl) phases. Vickers hardness and compression yield strength of the plasma melted ingots is higher than those measured in a benchmark Ti-46Al-8Ta (at.%) alloy with convoluted γ+α₂ type of microstructure. The compression strength of the ingot prepared from the cold compacted semi-products is by 20% higher than that of the ingot prepared from the master Al-Ta alloy mixed with the Ti sponge.

Key words
titanium aluminides, TiAl, melting, microstructure, mechanical properties

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