Modified Zerilli-Armstrong and Khan-Huang-Liang constitutive models to predict hot deformation behavior in a powder metallurgy Ti-22Al-25Nb alloy

In order to establish constitutive models for a fine-grained Ti-22Al-25Nb alloy fabricated by spark plasma sintering under high vacuum, isothermal uniaxial compression tests are conducted at the different deformation conditions of 950–1070 °C and 0.001–1 s−1. Using the friction-corrected experimental data, the modified Zerilli-Armstrong model and the Khan-Huang-Liang model are developed in the α2 + β/B2 + O triple-phase and α2 + B2 two-phase fields, respectively. The determination coefficient (R2) and average absolute relative error (AARE) of the developed models are 0.9773 and 8.73%, 0.9831 and 12.36%, respectively. Based on the analyzing the reason of large deviation, the modified Zerilli-Armstrong and Khan-Huang-Liang models are improved. The prediction accuracy of the improved constitutive models is improved to 0.9896 and 6.14%, 0.9891 and 6.82%, respectively. This indicates that the improved versions of the modified ZA and KHL models are very appropriate for predicting the hot deformation behavior of a fine-grained Ti-22Al-25Nb alloy fabricated by spark plasma sintering.