Low-melting zirconium alloys

A.M. Savchenko1, Y.V. Konovalov1, A.V. Laushkin1, O.I. Yuferov1
1Stock Company «A.A. Bochvar High-Technology Research Institute of Inorganic Materials» (SC VNIINM) 123060, Moscow, Russia (VNIINM)
A novel class of low-melting Zr-based alloys has been developed. These are deep triple and quadruple eutectics with melting points from 690 to 860°C, which are very low for zirconium. Projections of the crystallization areas in the Zr-rich corner of Zr-Be-Fe and Zr-Cu-Fe systems are given. Apart from eutectic zirconium alloys, hypoeutectic alloys, in which the melting point changes not significantly, but the ductility is greatly enhanced, can also be used. An important feature of these alloys is the possibility of additional alloying up to 3 to 5 mass per cent retaining the low melting temperature. As alloying elements, Nb, Cu, Al, Mo, Si etc. can be used. The additional alloying can be done to enhance the corrosion resistance, castability, capillary properties and improve the neutron-physics characteristics. The temperature coefficient of linear expansion and thermal conductivity of alloys is higher than that of zirconium. Corrosion resistance in water and superheated steam remained high, characteristic of zirconium alloys. Capillary properties of alloys are very high, so they can be used as cast ones as well as a solder for brazing of different materials. These alloys can be also produced in an amorphous state as granules and strips. They can be used as hydrides for hydrogen accumulation too. It is promising to use the low-melting Zr-based alloys proposed in nuclear engineering as matrix materials for dispersion fuel elements. The fuel compositions including these alloys have a high thermal conductivity and compatibility and uranium level 30 to 50 % higher than in the fuel elements of VVER and PWR reactors. The use of new dispersion fuel can lead to improved neutron-physical characteristics of the reactors, increase burn-out, reduce fuel temperature and improve fuel efficiency.
Received: 30 March 2017   Revised: 04 May 2017   Accepted: 13 June 2017
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