Tensile creep of an additively manufactured Ti-48Al-2Cr-2Nb alloy with a layered microstructure

This study investigated the tensile creep behavior of Ti-48Al-2Cr-2Nb alloy with a layered microstructure produced by selective electron beam melting (SEBM). Creep tests were conducted on a range of temperatures from 750 to 850 °C, and stresses from 120 to 280 MPa. The stress exponents (n) varied from 6.3 to 5.1 with increasing temperature, and the apparent activation energy (Q_c) was determined to be 436.8 kJ/mol under 200 MPa. The observations indicated that at 750 °C and 800 °C, cross-slip bands and deformation twins tend to form in coarse grain (CG) regions. At 850 °C, extensive dynamic recrystallization (DRX) concentrated in fine-grained (FG) regions and the heterogeneous interfaces, characterized by discontinuous dynamic recrystallization (DDRX). A small number of continuous dynamic recrystallization (CDRX) grains appeared in CGs and were characterized by sub-grain rotation. The results suggest that local stress concentration induced by deformation twins and cross-slip bands within CGs may nucleate and merge to form cavities. © 2024 Elsevier B.V.