Fe-Sn-Zr Experimental phase diagram. New results at 800°C

TOLOSA MARTÍN RODRIGO; CORVALÁN CAROLINA; NIEVA NICOLÁS; ARIAS DELIA

Santos

Congreso; Discussion Meeting on Thermodynamics of Alloys. TOFA 2016;; 2016

The University of São Paulo School of Engineering

Zr based alloys are broadly used in the field of nuclear technology. Zr, alloyed with Sn and Fe, is the main component of Zircaloy-like alloys, still used nowadays as both structural elements and containers for burnable elements in nuclear reactors. This ternary metallurgical system is also a component of more recently developed alloys, such as the Zirlo-type. Although Zr is the main component in all of them, knowing the phase diagram of its components as fully as possible is both useful and important.It is the purpose of the present study to analyze, with experimental techniques, the Fe-Sn-Zr system phase diagram at the 800 °C isothermal cut, in those areas of the corresponding Gibbs triangle which have not been solved yet. For this purpose, a set of ternary alloys has been designed and prepared. These alloys have been made by casting in an arc furnace with non-consumable tungsten electrode. Then the samples were given a long isothermal heat treatment at 800°C.Once heat treated, the microstructure of samples was observed and the phases present were assessed in order to establish their composition and crystalline structure. The techniques used were metallographic analysis with optical and electronic microscope, X-ray diffraction and quali-quantitative microanalysis by means of energy dispersion spectrometry.At the temperature in question, the following results were reached: the existence of the ternary compound Fe6Sn6Zr was verified, phase X? presence was discovered and fields of existence for two and three phases were determined. Finally, the phase boundaries in the region under study were drawn, thus completing part of the phase diagram at the 800 °C isothermal cut.