SEM, 2019, #3, 55-61 pages
Journal Современная электрометаллургия
Publisher International Association «Welding»
ISSN 2415-8445 (print)
Issue № 3, 2019 (September)
Uniformity of microstructure of Ti–TiB alloy produced under the conditions of electron beam remelting
P.I. Loboda1, D.A. Remisov1, S.G. Grigorenko2, V.A. Berezos2, A.Yu. Severin2
NTUU «Igor Sikorskii Kyiv Polytechnic Institute».
37 Peremohi Ave., 03056, Kyiv, Ukraine. E-mail: firstname.lastname@example.org
E.O. Paton Electric Welding Institute of the NAS of Ukraine.
11 Kazimir Malevich Str., 03150, Kyiv, Ukraine. E-mail: email@example.com
Studied was the formation of microstructure of Ti–TiB composite, which is obtained during production of 110 mm diameter ingots under the conditions of electron beam melting. Reinforced titanium-based metal-ceramic composite was produced using crushed sponge of TG-90 grade titanium of –30…+10 mm size and titanium diboride with average particle size of 5 μm. Microstructure, phase composition and some properties of directionally crystallized titanium — titanium diboride alloy were studied. It is shown that both in the longitudinal and transverse sections the alloy microstructure is represented by light-grey continuous matrix phase and darker phase in the form of elongated grains or fibres. It is established that during melting titanium diboride interacts with titanium with formation of titanium monoboride. The alloy microstructure in the plane of transverse and longitudinal sections is a titanium matrix with diboride phase inclusions. The extent of the diboride phase in the longitudinal direction is 50–100 times greater than that of the boride phase in the ingot cross-section that is indicative of formation of boride phase inclusions elongated in the direction of movement of the crystallization front. The microstructure of the ingot central part is characterized by much larger in size inclusions of the boride phase both in the longitudinal and transverse sections that can be due to heating from the melt surface and lowering of crystallization rate. It is shown that during directional crystallization of a eutectic alloy of titanium — titanium boride a composite forms, which is a matrix of commercially pure titanium and core inclusions of titanium boride, elongated in the direction of movement of the crystallization front. Ref. 10, Table 1, Fig. 10.
Key words: ingot; electron beam melting; titanium; alloy; structure; diboride; metal-ceramic composite; titanium alloys; reinforced titanium
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