In-situ study on phase transformations of novel metastable beta zirconium alloys and their comparison with well-known metastable beta titanium alloys
Abstract
Zirconium and titanium are in the same group of periodic table of elements and therefore some of their properties are similar. For example, they occur in the same crystallographic structures - HCP α phase at room temperature and BCC β phase at temperature above β transus.
Although titanium alloys and their phase transformations have been already well-studied, zirconium alloys with higher amount of β-stabilizing alloying elements are rather unexplored. While titanium alloys are nowadays widely used for example in aircraft industry or biomedicine, zirconium is utilized in nuclear industry due to its low cross section for neutron capture.
In this work, phase transformations of metastable Zr-(12/15)Nb alloys were studied in-situ during heating using resistivity measurements and synchrotron X-ray diffraction. Based on the results, SEM and TEM observations were made on ex-situ prepared samples.
For first characterization of mechanical properties, microhardness was measured. Achieved results were compared with Ti-(12/15/18)Mo alloys.
It was confirmed that phase transformations in both Zr-Nb and Ti-Mo systems are qualitatively similar. After quenching from temperature above temperature of β-transus, α phase does not precipitate and during subsequent linear heating to temperatures in range 300 °C - 500 °C, metastable ω phase grows.
On the other hand, quantitatively, these systems behave differently.