Abstract
The binary phase diagram of the tantalum–tungsten (Ta–W) system shows a solid solution across all temperatures. This is in conflict with density functional theory (DFT) predictions, which indicate the formation of ordered intermetallic phases at low temperatures, specifically Ta3W and TaW3. In this study, we investigate whether these predicted phases can be experimentally observed. Thin films with varying compositions were synthesized by magnetron sputter deposition and subsequently structurally characterized to detect potential compositional ordering. With this work, we aim to fill the gap in the low-temperature region of the Ta–W binary phase diagram and to reconcile, on thermodynamic grounds, the apparent disagreement between ab initio-based DFT and experiment-based CalPhaD assessments. The experimental findings are shown to be consistent with this picture, but do not by themselves provide conclusive evidence of long-range ordering.