THE EFFECT OF PREPARATION METHODS ON A MICROSTRUCTURE OF THE NI3AL-BASED ALLOYS ALLOYED WITH MOLYBDENUM

1 POHLUDKA Martin
Co-authors:
1 Malcharcziková Jitka 1 PETLÁK Daniel
Institution:
1 VSB - Technical University of Ostrava, Ostrava, Czech Republic, EU martin.pohludka@vsb.cz, jitka.malcharczikova@vsb.cz, daniel.petlak@vsb.cz
Conference:
24th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, June 3rd - 5th 2015
Proceedings:
Proceedings 24th International Conference on Metallurgy and Materials
Pages:
1619-1624
ISBN:
978-80-87294-58-1
ISSN:
2694-9296
Published:
12th January 2015
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
299 views / 103 downloads
Abstract

A preparation of alloys based on the Ni3Al intermetallic compound alloyed with molybdenum by classical castings methods, such as an induction melting, is limited by a high melting point of molybdenum (2623 °C). Decreasing of the melting point on the value of 1417 °C was reached by a preparation of the Ni-15Mo (wt.%) master alloy by plasma metallurgy. The master alloy was used as an input material for a preparation of the Ni-7Al-14Mo (wt.%) alloy by an induction melting with a centrifugal casting. Castings of the Ni-7Al-14Mo alloy were directionally solidified in a resistance furnace working on the Bridgman method principle at the rates of 20 and 50 mm/h and the constant thermal gradient of 75 °C/cm. All experimental alloys were examined by a chemical and structural analysis. A matrix of the master alloy was homogeneous without precipitates and formed by the MoNi8 phase. Matrixes of the casting and directionally solidified rods of the Ni-7Al-14Mo alloy consisted of the Ni3Al phase and the solid solution of aluminum in nickel, mutually arranged as a mesh. There were small precipitates rich in molybdenum situated along grain boundaries. A structure of the casting and the directionally solidified rods was polycrystalline, but the grains of the directionally solidified rods were oriented in a growth direction of solid-liquid interface.

Keywords: Ni-7Al-14Mo alloy, Ni-15Mo alloy, plasma metallurgy, directional solidification, microstructure

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