Microstructural and Strength Changes During Multi-Axial Forging of Ta-10 wt% W and its Comparison with Ta

The study aims to bring out the effect of microstructural modification and W addition in TaW on the strength as these alloys find applications in ballistics, high temperature and corrosive environments. Coarse-grained tantalum-10 wt% tungsten (Ta-10 W) was multi-axially forged (MAF) to 3, 6, and 9 passes corresponding to equivalent strains of 2.4, 4.8 and 7.2, respectively. The MAF Ta-10 W samples were characterized for their microstructural and mechanical properties. The average grain size decreased from 20 μm in the starting material to 3 μm after 3 passes and to 0.38 μm after 9 passes. The fraction of high angle grain boundaries (\(\:{f}_{hagb}\)) increased from 0.26 (3 passes) to 0.56 (9 passes) and the fraction of recrystallized grains (\(\:{f}_{recry}\)) increased from 0.31 (3 passes) to 0.92 (9 passes). The yield stress increased from 964 MPa after 3 passes to 1202 MPa after 9 passes. It was found that the contribution from GBs as compared to that from dislocations was lower after 3 passes than after 9 passes. The addition of tungsten to tantalum increased the flow locus during MAF and yield stress of MAF samples to almost double as compared to Ta. As compared to MAF Ta, MAF Ta-10 W showed finer grains, higher \(\:{f}_{hagb}\), and higher \(\:{f}_{recry}\).

Graphical Abstract