Solid-state amorphization in Ta-based alloy system by mechanical alloying technique

Formation of Cu–Zr–Ti amorphous powders with B and Si additions by mechanical alloying technique

“…The former ensures that the interdiffusion of the two metals will lead to the formation of a metastable amorphous alloy instead of a stable crystalline intermetallic compound, and the latter provides a large difference of free energy between the amorphous state and the crystalline state of the pure element. Therefore, from a thermodynamic point of view, it is expected that the formation of amorphous state should be much easier for compositions with a large negative heat of mixing (H m ) as reported by many researchers [16,17,18]. The values of H m, as calculated by the Miedema model [19] are for Cu-Ti (−9 kJ/mol), Cu-Zr (−23 kJ/mol), Ti-B (−43 kJ/mol), Zr-B (about −56 kJ/mol), Ti-Si (−49 kJ/mol), and Zr-Si (about −67 kJ/mol).…”

On the Phase Transformation in Mechanically Alloyed Ni-Nb and Ni-Ta and Ni-Nb-Ta Powders

“…For longer milling times it was noted the disappearing of Nb and Ta peaks and the formation of halos suggesting that amorphous structures were formed after milling for 5h. Various works reported on the formation of amorphous structures in Ni-Nb and Ni-Ta alloys [8,9,14,16,17]. In contrast, the Ni-25Ta powders indicated the presence of unknown intermetallic peaks after milling for 300 min (see Fig.…”

“…According to the ternary phase diagram of the Ni-Nb-Ta system, the Ni 3 Nb and Ni 3 Ta phases form a large single-phase region [6]. The route of solid-state powders processing by high-energy ball milling is able to produce homogeneous and nanostructured materials [7][8][9][10]. Initially, these techniques were used for producing some oxide-dispersion-strengthened (ODS) materials such as those based on Ni and Fe superalloys [7].…”

“…Initially, these techniques were used for producing some oxide-dispersion-strengthened (ODS) materials such as those based on Ni and Fe superalloys [7]. Depending on the composition alloy and milling parameters different metastable structures as extended solid solution or amorphous phase can be formed during milling [8][9][10]. This work discusses on the phase transformation in mechanically alloyed Ni-Nb and Ni-Ta and Ni-Nb-Ta powders.…”