The preferred slip plane of nuclear material of Hafnium: A first-principles study

In this work, first-principles calculations based on density functional theory (DFT) were applied to simulate the general stacking faults energy (GSFE) of all the possible basal, prismatic and pyramidal planes of Hafnium (Hf), which was applied as an ideal neutron absorber in nuclear industry. The calculations reveal that unlike titanium (Ti) and zirconium (Zr) having preferred slip plane of prism, the same group of Hf has lower GSFE in basal plane (I2) than that in prismatic plane (SF1), i.e., the preferred slip plane of Hf is basal rather than prismatic. Our prediction well meets the recent experimental result. In order to ensure the precise of the stacking faults energy calculations, in-plane and out-of-plane directions of relaxations were considered in detail. For basal and prism I plane, the effect from in-plane direction relaxation on GSFE was negligible, while for prism II and pyramidal planes, both in-plane and out-of-plane directions of relaxations should be included in the calculations.