摘要
The hot deformation behavior of Al0.3Co1.5CrFeNi1.5Ti0.2 high-entropy alloy was studied at temperatures and strain rates varying from 923 to 1373 K and 10−3 to 1s−1, respectively. A constitutive equation was formulated to characterize material flow within these conditions and predict its behavior under similar or extended conditions. Stress exponent and deformation activation energy were determined to be 4.44 and ∼490 kJ/mol, respectively, suggesting that the material undergoes high-temperature deformation primarily controlled by dislocation climb. Moreover, at 923 K, the power law breakdown was observed, with no flow softening occurring up to a true strain of 0.5. The processing map identified optimal deformation conditions, achieving highest efficiency (∼34 %), at strain rates of 0.03−1s−1, and temperatures > 1300 K. Instability domain (strain rate range: 0.01−1s−1, temperatures: 923–1165 K), was characterized by presence of voids and cracks. Further, transmission electron microscopy study highlighted the dynamic development of L12, B2 and σ phases at different temperatures and identified their correlation with instability domains in the processing map. The predominant deformation mechanisms were identified as dislocation climb and discontinuous dynamic recrystallization (DDRX). Electron back scattered diffraction microstructural investigations confirmed the occurrence of DDRX.
•Hot deformation behaviour of non-equiatomic AlCoCrFeNiTi HEA was firstly reported.•At 923 K, power law break down was observed.•Deformation mechanisms included dislocation climb and DDRX.•Dynamic development of different phases was identified at different temperatures.