Influence of Deposition Temperature on the Phase Evolution of HfNbTiVZr High-Entropy Thin Films

Abstract

In this study, we show that the phase formation of HfNbTiVZr high-entropy thin films is strongly influenced by the substrate temperature. Films deposited at room temperature exhibit an amorphous microstructure and are 6.5 GPa hard. With increasing substrate temperature (room temperature to 275 °C), a transition from an amorphous to a single-phased body-centred cubic (bcc) solid solution occurs, resulting in a hardness increase to 7.9 GPa. A higher deposition temperature (450 °C) leads to the formation of C14 or C15 Laves phase precipitates in the bcc matrix and a further enhancement of mechanical properties with a peak hardness value of 9.2 GPa. These results also show that thin films follow different phase formation pathways compared to HfNbTiVZr bulk alloys.

Experimental and theoretical evidence of charge transfer in multi-component alloys – how chemical interactions reduce atomic size mismatch

“…The non-relaxed multi-component alloy with an (undistorted) bcc structure has a lattice constant of 3.40 Å, whereas the supercell relaxation yielded a slightly smaller lattice constant of 3.36 Å. Previous theoretical calculations on the ideal (undistorted) alloy have reported a 3.40 Å lattice constant,36 in excellent agreement with our calculations, whereas previous experimental results have reported values in the range of 3.37 -3.46 Å 20,21,[36][37][38]. The values are plotted in Figure1together with data for the pure elements.…”

“…To verify the theoretical modelling results, a multi-component alloy sample deposited within the framework of a previous study 21 was studied further, together with elemental references. XPS analysis showed that the coating had a near equimolar composition: Hf 22 Nb 19 Ti 18 V 19 Zr 21 .…”

“…The HfNbTiVZr system was chosen as a demonstrator system, as it is a known entropystabilised phase, 20 which can be produced as thin films. 21 Furthermore, the presence of Zr and Hf suggest that a (comparably) large distortion and charge transfer is expected, 15 making the system suitable for further studies.…”

Properties of multicomponent (Mn-Ni-Co-Al-Si-Ti) oxide spinel hierarchically organized nanostructures deposited by magnetron sputtering in two temperatures.

“…The process of phase separation during film growth was observed by F. Fritze et. all during deposition of HfNbTiVZr thin films [30]. The Authors observed growth of different phases on different substrate temperatures without annealing, but the substrate temperature was much lower than the temperature of phase separation for bulk samples.…”

Phase Engineering of High‐Entropy Alloys

“…A nanocomposite structure, which was composed of nanocrystalline grains embedded in an amorphous matrix, was formed, leading to an increase in hardness beyond the Hall–Petch breakdown. Fritze et al discovered that increasing the substrate temperature could promote phase transition in HfNbTiVZr HEAs 147. The HEAs, transforming from amorphous phase to BCC phase, then to BCC/Laves phase during this process, exhibited different hardness values, which showed the composite effect of phase structure.…”