Structure and Properties of Directionally Solidified Mo-8.7 Si-18 B Alloys

Authors

DOI:

https://doi.org/10.20535/1810-0546.2016.2.59788

Keywords:

High-temperature structural materials, Crucible-free zone melting, Directional solidification, Mo–Si–B-system, Microstructure, Phase composition, Microhardness, Fracture toughness

Abstract

Background. The research of alloys of the Mo–Si–B-system, which are a new type of heat-resistant alloys for the manufacture of gas turbine blades to replace nickel single crystal superalloys.

Objective. The purpose is to study the effect of the kinetic parameters of crucibleless melting zone and redundancy of boron on the regularity of directionally solidified eutectic Mo-8.7 at. % Si-18 at. % B alloy’s formation of structure and mechanical properties.

Methods. Directionally solidified Mo-8.7 at. % Si-18 at. % B and Mo-8.7 at. % Si-18.5 at. % B alloys were produced by crucibleless melting zone of not sintered powder compacts. Microstructure analysis of the obtained reinforced composites and chips, X-ray analysis, the study of micromechanical properties with a dispersion analysis of the data were conducted.

Results. Directionally solidified Mo-8.7 % Si-18 % B, Mo-8.7 % Si-18.5 % B alloys and fast solidified Mo-8.7 % Si-18.5 % B alloy were produced, their microstructure consists of intermetallic matrix reinforced with inclusions of solid solution of molybdenum. Integrated micro hardness of the received alloys reaches 11.86 ± 1.49 GPa and fracture toughness – 6.92 ± 0.68 MPa×ml/2.

Conclusions. The increase of the rate of crystallization leads to a natural refinement of the structure and increase of the anisotropy in matrix phase. It is shown that the introduction of boron in amount of 0.5 at. % leads to a decrease of the equilibrium from Mo-Mo5SiB2-Mo3Si to Mo-Mo5SiB2-Mo2B. The microhardness is anisotropic and fracture toughness is mostly isotropic.

Author Biographies

Юрій Іванович Богомол, National Technical University of Ukraine "Kyiv Polytechnic Institute"

Iurii I. Bogomol, Dr.-Ing., assistant professor, associate professor at the Department of high temperature materials and powder metallurgy of the Faculty of physical engineering

Ольга Ігорівна Попович, National Technical University of Ukraine "Kyiv Polytechnic Institute"

Olha I. Popovych, bachelor, student (master) at the Department of high temperature materials and powder metallurgy of the Faculty of physical engineering

Маня Крюгер, Faculty of Mechanical Engineering, Otto von Guericke University of Magdeburg

Manja Krueger, Dr.-Ing., Jun.-Prof., Jun.-Prof.  in the field of materials at the Institute of Materials and Joining Technology

Петро Іванович Лобода, National Technical University of Ukraine "Kyiv Polytechnic Institute"

Petro I. Loboda, corresponding member of National Academy of Sciences of Ukraine, Dr.-Ing. habil, full professor, dean of the Faculty of physical engineering

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Published

2016-04-20

Issue

No. 2 (2016): Engineering

Section

Art

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