Interdiffusion behaviors and mechanical properties of Hf-X (X=Nb, Ta) binary systems

The diffusion behaviours and mechanical properties of the Hf-X (X = Nb, Ta) systems have been investigated using diffusion couples in the temperature range from 1150 °C to 1500 °C. The interdiffusion coefficients of Hf-X (X = Nb, Ta) systems were extracted using forward simulation analysis (FSA) based on the Sauer-Freise method. According to the results, the interdiffusion coefficients of the Hf-X (X = Nb, Ta) systems decreased as the Nb or Ta content increased. In the meantime, the diffusion activation energies of Hf-X (X = Nb, Ta) systems increased as the Nb or Ta content increased. Finally, the hardness and Young’s moduli of the Hf–Nb and Hf–Ta systems were determined by nanoindentation tests. The largest hardness values of the Hf–Nb and Hf–Ta were 5.2 GPa and 5.3 GPa, respectively. Young’s largest moduli of the Hf–Nb and Hf–Ta were 221 GPa and 238 GPa, respectively. The present results provide helpful diffusional data and mechanical properties for the materials design, research and development of hafnium-based alloys.