Stacking fault energy and ductility in a new zirconium alloys: A combined experimental and first-principles study

A combined experimental and first-principles study was performed on a new zirconium alloy. Experimental results showed that alloy elements, such as Cu, Nb, etc., mainly dissolve into the matrix of zirconium alloy where a larger number of slip traces are detected except for dislocation after deformation. First-principles calculation showed that Nb significantly reduces unstable stacking fault energy (gamma(us)), leading to the increment of {10 (1) over bar0} < 11 (2) over bar0 > slip systems activity, and the stable and unstable stacking fault energies are both dramatically decreased with the addition of Cu, which is beneficial to the activation of the {0001} <10<(1)over bar>0> and {10 (1) over bar1} <11<(2)over bar>3> slip systems. It is suggested that basal or pyramidal plane becoming the second primary slip system gives rise to excellent forming properties, especially ductility. A new zirconium alloy containing Nb, Fe, and Cu elements was tested through uniaxial tension tests with digital image correlation (DIC) equipment. Both experimental and theoretical results showed that adding Nb, Fe, and Cu can enhance the ductility of zirconium alloys. Electronic properties of various stacking faults were also analyzed to explore the origin of excellent forming properties. Added element and its matching amount can be considered from the aspects of electronegativity and concentration effect for the preparation of zirconium alloys with excellent forming properties.