Abstract
Melting metallurgy is still the most frequently used and simplest method for the processing of metallic materials. Some of the materials (especially intermetallics) are very difficult to prepare by this method due to the high melting points, poor fluidity, or formation of cracks and pores after casting. This article describes the processing of Ti-Al-Si alloys by arc melting, and shows the microstructure, phase composition, hardness, fracture toughness, and compression tests of these alloys. These results are compared with the same alloys prepared by powder metallurgy by the means of a combination of mechanical alloying and spark plasma sintering. Ti-Al-Si alloys processed by melting metallurgy are characterized by a very coarse structure with central porosity. The phase composition is formed by titanium aluminides and titanium silicides, which are full of cracks. Ti-Al-Si alloys processed by the powder metallurgy route have a relatively homogeneous fine-grained structure with higher hardness. However, these alloys are very brittle. On the other hand, the fracture toughness of arc-melted samples is immeasurable using Palmqvist’s method because the crack is stopped by a large area of titanium aluminide matrix.
Highlights
Titanium intermetallics with other light elements are prospective high-temperature alloys, applicable especially for construction components working at high temperatures under static loads [1,2,3,4,5]
TiAl15Si15 alloys consists of titanium silicide (Ti and titanium aluminide (TiAl)
TiAl15Si15 alloys consists of titanium silicide (Ti55Si33) and titanium aluminide (TiAl)
Summary
Titanium intermetallics with other light elements (for example aluminium or silicon) are prospective high-temperature alloys, applicable especially for construction components working at high temperatures under static loads [1,2,3,4,5]. They are considered for high-temperature service because they offer a balance of oxidation resistance and mechanical properties at higher temperatures superior to conventional titanium alloys [6,7]. Slow cooling rates after centrifugal casting lead to the Materials 2019, 12, 3084; doi:10.3390/ma12193084 www.mdpi.com/journal/materials
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