Microstructural Phase Evolution during Spark Plasma Sintering of Mechanically Alloyed Ti-Based Partially Amorphous Powders

Abstract

Ti-based amorphous alloys exhibit superior mechanical properties compared to conventional Ti alloys used for many practical applications. In the present work, Ti<inf>75.48</inf>Fe<inf>14.68</inf>Si<inf>9.84</inf> (T<inf>75</inf>) and Ti<inf>70.54</inf>Fe<inf>23.52</inf>Si<inf>5.91</inf> (T<inf>70</inf>) (in wt.%) glass-forming compositions have been chosen, and mechanical alloying up to 100 h was performed to amorphize both the compositions. After 100 h mechanical alloying, partially amorphous powders could be synthesized as confirmed by XRD and TEM analyses. The milled powders were then consolidated using spark plasma sintering (SPS) at uniaxial pressure of 50 MPa and sintering temperatures of 800 °C and 1000 °C. It was observed that only a little amorphous phase was retained in the consolidated bulk samples, attributed to presence of crystalline phases in the milled powders which acted as nucleation sites to promote devitrification of the powders of both compositions. The microhardness and nano-hardness of T<inf>75</inf> and T<inf>70</inf> bulk samples obtained from sintering 60 h milled powders at 800 °C were 14.95 ± 0.6 GPa and 9.72 ± 0.5 GPa, respectively. The nano-hardness of the same bulk samples was 40.85 ± 4.4 GPa and 40.9 ± 5.7 GPa, respectively. These high hardness values can be attributed to evolution of hard intermetallic phases during consolidation. © 2025 Elsevier B.V., All rights reserved.